LITHIUM-ION BATTERY CHEMISTRY DEFINING IMPORTANT PARAMETERS, ADVANTAGES, DISADVANTAGES AND BATTERY APPLICATIONS
vijay tharad
Director Operations at Corporate Professional Academy for Technical Training & Career Development
Lithium-ion Battery
A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. In comparison with other commercial rechargeable batteries, Li-ion batteries are characterized by higher specific energy , higher energy density , higher energy efficiency , a longer cycle life, and a longer calendar life. Also noteworthy is a dramatic improvement in lithium-ion battery properties after their market introduction in 1991: within the next 30 years, their volumetric energy density increased threefold while their cost dropped tenfold.
Lithium-ion batteries can be a safety hazard if not properly engineered and manufactured because they have flammable electrolytes that, if damaged or incorrectly charged, can lead to explosions and fires. Much progress has been made in the development and manufacturing of safe lithium-ion batteries. Lithium-ion solid-state batteries are being developed to eliminate the flammable electrolyte.
Research areas for lithium-ion batteries include extending lifetime, increasing energy density, improving safety, reducing cost, and increasing charging speed, among others. Research has been under way in the area of non-flammable electrolytes as a pathway to increased safety based on the flammability and volatility of the organic solvents used in the typical electrolyte. Strategies include aqueous lithium-ion batteries, ceramic solid electrolytes, polymer electrolytes, ionic liquids, and heavily fluorinated systems.
There are several specific advantages to lithium-ion batteries. The most important advantages are their high cell voltage, high energy density, and no memory effect.
Lithium-ion batteries are used in many laptop computer batteries, cordless power tools, certain electric cars, electric kick scooters, most e-bikes, portable power banks, and LED flashlights.
Generally, the negative electrode of a conventional lithium-ion cell is graphite made from carbon. The positive electrode is typically a metal oxide or phosphate. The electrolyte is a lithium salt in an organic solvent The negative electrode (which is the anode when the cell is discharging) and the positive electrode (which is the cathode when discharging) are prevented from shorting by a separator. The electrodes are separated from external electronics with a piece of metal called a current collector.
The negative and positive electrodes swap their electrochemical roles (anode and cathode) when the cell is charged. Despite this, in discussions of battery design the negative electrode of a rechargeable cell is often just called "the anode" and the positive electrode "the cathode".
In its fully lithiated state of LiC6, graphite correlates to a theoretical capacity of 1339 coulombs per gram (372 mAh/g). The positive electrode is generally one of three materials: a layered oxide (such as lithium cobalt oxide, a polyanion (such as lithium iron phosphate or a spinel (such as lithium manganese oxide More experimental materials include graphene-containing electrodes, although these remain far from commercially viable due to their high cost.
Lithium reacts vigorously with water to form lithium hydroxide (LiOH) and hydrogen gas. Thus, a non-aqueous electrolyte is typically used, and a sealed container rigidly excludes moisture from the battery pack. The non-aqueous electrolyte is typically a mixture of organic carbonates such as ethylene carbonate and propylene carbonate containing complexes of lithium ions. Ethylene carbonate is essential for making solid electrolyte interphase on the carbon anode, but since it is solid at room temperature, a liquid solvent (such as propylene carbonate or diethyl carbonate is added.
Current collector design and surface treatments may take various forms: foil, mesh, foam (dealloyed), etched (wholly or selectively), and coated (with various materials) to improve electrical characteristics.
Depending on materials choices, the voltage, energy density, life, and safety of a lithium-ion cell can change dramatically. Current effort has been exploring the use of novel architectures using nanotechnology to improve performance. Areas of interest include nano-scale electrode materials and alternative electrode structures.
Electrochemistry
The reactants in the electrochemical reactions in a lithium-ion cell are the materials of the electrodes, both of which are compounds containing lithium atoms. Although many thousands of different materials have been investigated for use in lithium-ion batteries, the usable chemistry space for this technology, which has been made into commercial applications, is extremely small. All commercial Li-ion cells use intercalation compounds as active materials. The negative electrode is usually graphite , although silicon is often mixed in to increase the capacity. The solvent is usually lithium hexaflurophosphate , dissolved in a mixture of organic carbonates. A number of different materials are used for the positive electrode, such as LiCoO2, LiFePO4, and lithium nickel manganese cobalt oxides.
During cell discharge the negative electrode is the anode and the positive electrode the cathode: electrons flow from the anode to the cathode through the external circuit. An oxidation half-reaction at the anode produces positively charged lithium ions and negatively charged electrons. The oxidation half-reaction may also produce uncharged material that remains at the anode. Lithium ions move through the electrolyte; electrons move through the external circuit toward the cathode where they recombine with the cathode material in a reduction half-reaction. The electrolyte provides a conductive medium for lithium ions but does not partake in the electrochemical reaction. The reactions during discharge lower the chemical potential of the cell, so discharging transfers energy from the cell to wherever the electric current dissipates its energy, mostly in the external circuit.
During charging these reactions and transports go in the opposite direction: electrons move from the positive electrode to the negative electrode through the external circuit. To charge the cell the external circuit has to provide electrical energy. This energy is then stored as chemical energy in the cell (with some loss, e. g., due to coulombic efficiency lower than 1).
Both electrodes allow lithium ions to move in and out of their structures with a process called insertion (intercalation) or extraction (deintercalation), respectively.
As the lithium ions "rock" back and forth between the two electrodes, these batteries are also known as "rocking-chair batteries" or "swing batteries" (a term given by some European industries).
The following equations exemplify the chemistry (left to right: discharging, right to left: charging).
The negative electrode half-reaction for the graphite is
LiC6????C6+Li++e?
The positive electrode half-reaction in the lithium-doped cobalt oxide substrate is
CoO2+Li++e?????LiCoO2
The full reaction being
LiC6+CoO2????C6+LiCoO2
The overall reaction has its limits. Overdischarging supersaturates lithium cobalt oxide, leading to the production of lithium oxide. possibly by the following irreversible reaction:
Li++e?+LiCoO2?Li2O+CoO
Over charging up to 5.2?volts leads to the synthesis of cobalt (IV) oxide, as evidenced by x-ray diffraction
LiCoO2?Li++CoO2+e?
The transition metal in the positive electrode, cobalt (Co), is reduced from Co4+ to Co3+ during discharge, and oxidized from Co3+ to Co4+ during charge.
The cell's energy is equal to the voltage times the charge. Each gram of lithium represents Faraday's constant/6.941, or 13,901 coulombs. At 3?V, this gives 41.7?kJ per gram of lithium, or 11.6?kWh per kilogram of lithium. This is a bit more than the heat of combustion of gasoline but does not consider the other materials that go into a lithium battery and that make lithium batteries many times heavier per unit of energy.
Note that the cell voltages involved in these reactions are larger than the potential at which an aqueous solutions would electrolyze.
Lithium-ion Battery
A lithium-ion battery, also known as the Li-ion battery, is a type of secondary (rechargeable) battery composed of cells in which lithium ions move from the anode through an electrolyte to the cathode during discharge and back when charging.?
The cathode is made of a composite material (an intercalated lithium compound) and defines the name of the Li-ion battery cell. The anode is usually made out of porous lithiated graphite. The electrolyte can be liquid, polymer, or solid. The separator is porous to enable the transport of lithium ions and prevents the cell from short-circuiting and thermal runaway.
Chemistry, performance, cost, and safety characteristics vary across types of lithium-ion batteries. Handheld electronics mostly use lithium polymer batteries (with a polymer gel as electrolyte), a lithium cobalt oxide (LiCoO2) cathode material, and a graphite anode, which offer high energy density.
Li-ion batteries, in general, have a high energy density, no memory effect, and low self-discharge.. One of the most common types of cells is 18650 battery, which is used in many laptop computer batteries, cordless power tools, certain electric cars, electric kick scooters, most e-bikes, portable power banks, and LED flashlights. The nominal voltage is 3.7 V.
Note that non-rechargeable primary lithium batteries (like lithium button cells CR2032 3V) must be distinguished from secondary lithium-ion or lithium-polymer, which are rechargeable batteries. Primary lithium batteries contain metallic lithium, which lithium-ion batteries do not.
Lithium battery may refer to:
Lithium-ion battery, a rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging
Solution of lithium tetrachloroaluminate lithium in thionyl chloride is the liquid cathode and electolyte of some lithium batteries, e.g. the lithium-thionyl chloride cell. Another cathode-electrolyte formulation is lithium tetrachloroaluminate + thionyl chloride + sulfur dioxide + bromine.
Other salts used in lithium battery electrolytes are lithium bromide, lithium perchloratee, lithium tetrafluroborate, and lithium hexafluroborate and lithium hexaflurophosphate; less-common ones arelithium chloride, lithium iodide, lithium chlorate, lithium nitrate, lithium hexafluroarsenate, lihium hexaflorosilicate (i.e. lithium and hexaflurosilicic acid), lithium bis(trifluoromethanesulfony)imide, and lithium trifluromethanesulfonate. A lithium-ion battery, also known as the Li-ion battery, is a type of secondary (rechargeable) battery composed of cells in which lithium ions move from the anode through an electrolyte to the cathode during discharge and back when charging.?
RECHARGEABLE
CELL CHEMISTRY KNOWN AS ANODE CATHODE
Lithium-iron disulfide Li-FES Lithium Iron-disulfide
Lithium-titanate Li Ti o Lithium Lithium manganese oxide or Lithium nickel manganese cobalt oxide
Lithium Cobalt oxide LiCoO Graphite Lithium Cobalt Oxide
Lithiumi ron phosphate LifePO Graphite Lithium Iron Phosphate
Lithium Manganese oxide LiMn2O Graphite Lithium manganese oxide
Lithium nickek Cobalt LiNiCoAlO Graphite Lithium Nickel Cobalt Aluminium oxide Aluminium oxide
Lithium Nickel Manganese LiNixMnyCoxyO Grapite Lithium Nickel cobalt oxide Manganese cobalt oxide
MATERIALS USED IN LITHIUM-ION BATTERIES
To date, several materials have been discovered and designed for components of LIBs and continuous efforts in order to improve electrochemical and cyclic performance are still ongoing. The performance of lithium-ion batteries significantly depends on the nature of the electrode material used. Typically, both the cathode and anode in a LIB have layered structures and allow Li+ to be intercalated or de-intercalated. The most common materials for various components of LIBs are given below:
The Best Places to Buy Lithium Batteries
Nowadays, many manufacturers are developing lithium batteries to meet their emerging demand. Different brands are known for their various particularities.
In this regard, several worldwide factories are well-known. The top 7 of these li-ion battery manufacturers are listed below.
● CATL (China)
● LG Chem ( South Korea)
● Panasonic Corporation (Japan)
● Samsung SDI (South Korea)
● SK Innovation (South Korea)
● Tesla (US)
What Are the Different Types of Lithium Batteries?
Lithium-ion battery types differ based on the lithium compound used in the anode electrode. There are six different types of lithium batteries:
Lithium Iron Phosphate (LiFePO4 or LFP)
LFP Batteries?have Lithium Ferrous Phosphate (LiFePO4) as the anode material, and this is one of the most widely adopted battery technologies nowadays. The anode is made of Lithium Iron Phosphate, one of the most stable and non-toxic lithium compounds.
It results in greater thermal stability in fully charged conditions. Whereas other lithium-ion battery types tend to exhibit thermal runaway in these conditions.
Characteristics of LFP Batteries
Advantages
Disadvantages of LFP batteries
Applications of LFP Batteries
Lithium Cobalt Oxide (LiCoO2 or LCO) Batteries
A Lithium Cobalt Oxide battery contains a Lithium Cobalt Oxide cathode and a graphite carbon anode. The unique selling point of lithium cobalt oxide batteries is their high energy density, which makes them the best choice for some particular applications with this requirement.
LCO batteries have a significantly low specific power. This means there is a limitation to their load capability, making them unsuitable for applications such as electric vehicles.
Characteristics of LCO Batteries
Advantages of LCO Batteries
Disadvantages of LCO Batteries
Applications of LCO Batteries
Lithium Manganese Oxide (LiMn2O4 or LMO) Batteries
In LMO batteries, the cathode is made of Lithium Manganese Oxide (LiMn2O4). This results in a three-dimensional spinel structure, enabling a better movement of lithium ions. This structure also makes it thermally more stable and safer. But it lowers the life span of the battery.
Lithium manganese oxide batteries have design flexibility and can be modified by adding other materials to improve their chemical properties. The specific energy of these batteries is low.
Characteristics of LMO Batteries
Advantages of LMO Batteries
Disadvantages of LMO Batteries
Applications
Lithium Nickel Manganese Cobalt Oxide (NMC, LiNiMnCoO2, or Li-NMC) Batteries
Li-NMC batteries are second only to LFP batteries. These batteries contain a cathode made of Nickel Manganese Cobalt Oxide (LiNiMnCoO2). Due to the presence of Manganese and Cobalt, Lithium Nickel Manganese Cobalt batteries offer the best benefits of LMO and LCO batteries.
The two common ratios of nickel, cobalt, and manganese are 1:1:1 or 5:3:2. Cobalt, being a rare element, is the major driving factor in the cost of these batteries.
Characteristics of Lithium Nickel Manganese Cobalt Oxide Batteries
Advantages of Lithium Nickel Manganese Cobalt Oxide Batteries
Disadvantages of NMC Batteries
Applications
Lithium Titanate Batteries (Li2TiO3 or LTO)
LTO batteries are different from the other lithium-ion batteries mentioned previously. These batteries use Lithium Titanate (Li2TiO3) as the anode material instead of a graphite anode. The cathode materials are Li-NMC or Lithium Manganese Oxide.
Characteristics of LTO Batteries
Advantages of LTO Batteries
Disadvantages of LTO Batteries
Applications
Lithium Nickel Cobalt Aluminium Oxide Battery (LiNiCoAlO2 or NCA) Batteries
NCA batteries replace the Manganese in NMC batteries with Aluminium. Due to the similar materials used and cell construction, NCA and NMC batteries share some common features. The addition of Aluminium to Lithium Nickel Cobalt Oxide adds the element of chemical stability to an NCA battery.
Characteristics of NCA Batteries
Advantages of NCA Batteries
Disadvantages of NCA Batteries
Applications
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Discharging and charging
During discharge, lithium ions (Li+ ) carry the current within the battery cell from the negative to the positive electrode, through the non-aqueous electrolyte and separator diaphragm.
During charging, an external electrical power source applies an over-voltage (a voltage greater than the cell's own voltage) to the cell, forcing electrons to flow from the positive to the negative electrode. The lithium ions also migrate (through the electrolyte) from the positive to the negative electrode where they become embedded in the porous electrode material in a process known as intercalation.
Energy losses arising from electrical contact resistance at interfaces between electrode layers and at contacts with current collectors can be as high as 20% of the entire energy flow of batteries under typical operating conditions.
The charging procedures for single Li-ion cells, and complete Li-ion batteries, are slightly different:
A single Li-ion cell is charged in two stages:
A Li-ion battery (a set of Li-ion cells in series) is charged in three stages:
During the constant current phase, the charger applies a constant current to the battery at a steadily increasing voltage, until the top-of-charge voltage limit per cell is reached.
During the balance phase, the charger/battery reduces the charging current (or cycles the charging on and off to reduce the average current) while the state of charge of individual cells is brought to the same level by a balancing circuit until the battery is balanced. Balancing typically occurs whenever one or more cells reach their top-of-charge voltage before the other(s), as it is generally inaccurate to do so at other stages of the charge cycle. This is most commonly done by passive balancing, which dissipates excess charge via resistors connected momentarily across the cell(s) to be balanced. Active balancing is less common, more expensive, but more efficient, returning excess energy to other cells (or the entire pack) through the means of a DC-DC converter or other circuitry. Some fast chargers skip this stage. Some chargers accomplish the balance by charging each cell independently. This is often performed by the battery protection circuit/battery management system (BPC or BMS) and not the charger (which typically provides only the bulk charge current, and does not interact with the pack at the cell-group level), e.g., e-bike and hoverboard chargers. In this method, the BPC/BMS will request a lower charge current (such as EV batteries), or will shut-off the charging input (typical in portable electronics) through the use of transistor circuitry while balancing is in effect (to prevent over-charging cells). Balancing most often occurs during the constant voltage stage of charging, switching between charge modes until complete. The pack is usually fully charged only when balancing is complete, as even a single cell group lower in charge than the rest will limit the entire battery's usable capacity to that of its own. Balancing can last hours or even days, depending on the magnitude of the imbalance in the battery.
During the constant voltage phase, the charger applies a voltage equal to the maximum cell voltage times the number of cells in series to the battery, as the current gradually declines towards 0, until the current is below a set threshold of about 3% of initial constant charge current.
Some battery terminology
Energy storage system : It basically refers to a battery pack system, meaning an electrical or mechanical combination of ECCs with appropriate thermal, electrical and mechanical specifications.
Intercalation : A process of inserting a guest ion in the host matrix. For this the host must have a layered structure. In the case of a Li-ion battery, the guest is the Li ion and the host is the layered electrode material.
De-intercalation : The process of taking out a guest ion from the host matrix.
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Capacity : Measure of total energy available with the battery or total charge stored in a battery, measured in ampere-hour (Ah). Ampere-hour is the capacity with the battery. It is basically the current that the battery can provide over a specified time period. So, the larger the current the more power can be released. Thus, according to the definition, a 10 Ah cell is able to supply 10 A for a 1 h period. But, according to the system specification, the rate with which the power is delivered by the battery may vary. (Example: a battery that delivers 10 A for 10 h delivers 10 A × 10 h = 100 Ah of capacity.)
Cell voltage : Cell voltage is represented by open-circuit voltage or working voltage, i.e. closed-circuit voltage.
Open-circuit voltage : This is the voltage between the positive and the negative electrodes when no external current flows (i.e. for no load condition). It is calculated by comparing the chemical potentials of the electrodes. To get it as high as possible, the chemical potential of positive electrode should be more than that of negative electrode. Also, the redox energies of the electrode should lie within the band gap of the electrolyte used.
Working voltage : The closed-circuit voltage between the positive and the negative electrodes connected through the external load.
Discharge rate or C-rate : The rate at which a battery is discharged relative to its maximum capacity. It is described in relation to the time of 1 h discharge.
Consider an example of a battery with capacity: 1000 mAh = 1 Ah.
For such a battery, the C-rate means that the entire battery is fully discharged (or charged) in 1 h. Likewise, a 2 C-rate means that the entire battery is fully discharged in 0.5 h, i.e. 30 min (1 h/2 C = 60 min/2 C = 30 min). A 1/5 C-rate would be equal to a 5 h discharge period (1 h/(1/5) C = 5 h).
A 0.05 or 1/20 C-rate would be equal to a 20 h discharge period. Thus, as the C-rate increases, the discharge time goes down and vice versa. This is a very important factor in order to evaluate the power output ability of the energy storage system. Some high-performance batteries can be charged and discharged above 1 C-rate with moderate stress.
Many EV systems require a continuous current draw that may be from 20 A to 400 A. In order to achieve such a requirement one can either use a single cell or lower Ah cells in a parallel configuration. For example, if the specification is 100 Ah at a 1 C-rate, this means that a battery can have 10 A of capacity over a 1 h period. The same cell can be rated up to a 5 C-rate for a period of 10 s, which can provide 500 A (100 A × 5) over 10 s.
Nominal voltage : Average voltage during the total discharge process of a battery at the rate of 0.2 C.
Nominal capacity : The total capacity during the discharge process of a battery at the rate of 0.2 C.
Discharge capacity : The total number of electrons transferred during a discharge process. A 3600 coulomb charge corresponds to a 1 Ah discharge capacity.
Depth of discharge (DOD) : Measure of how much of the percentage of battery capacity can be used relative to its total capacity for a particular application to avoid over discharge.
It is the percentage of decrease in the maximum capacity of a battery during the discharge process; 80% DOD is referred to as a deep discharge. For greater cycle life and safety of the storage system, DOD is kept at minimal value during the design.
State of charge (SOC) : A measure of how much capacity or power is left in a battery. Thus, it is opposite to DOD. DOD measures how much of the battery can be used, while SOC measures how much is left after a specified period of time for a particular application. It is always measured against DOD.
Duration time : The total time required by a battery to discharge until terminal discharge voltage.
Cut-off/terminal voltage : The final voltage between two electrodes during the complete charge or discharge process.
Self-discharge : Due to internal chemical reactions in a cell a decrease in stored capacity occurs even in the open-circuit condition, known as self-discharge. It causes a decrease in the shelf life of the battery.
Shelf/storage life : The best possible valid time that a battery can be stored or preserved without any load.
Cycle : The process of complete discharge and then charge is known as the cycle for a battery.
Cycle life : The number of times that a battery can be recharged or cycled, i.e. charged and discharged.
Over discharge : Occurring when a discharge voltage is below the specified terminal voltage value.
Over charge : Occurring when a charge voltage raises the specified terminal voltage value. It causes the cell to stop working due to emission of gases by decomposition of the electrolyte.
Constant voltage charge : A constant potential maintained during a charging process. When the battery voltage arrives at the specified voltage, this process terminates.
Constant current charge : A constant current maintained during a charging process. When the battery current arrives at the specified capacity, this process terminates.
Power efficiency : The ratio of the energy expended by all the external circuit components compared with the battery energy consumption.
Performance measuring key battery attributes
The datasheet of a battery always comes with some standard terms to represent its performance quality. The most common parameters that are used to validate the quality storage system are:
Characteristics of Lithium-ion Batteries
To compare and understand the capability of each battery, some important parameters are characteristic of each battery, also within a type of battery. These parameters are a reference when a battery is needed, and specific qualities are required since batteries are used in all types of devices and for infinite purposes.
Cell Voltage
The voltage of electric batteries is created by the potential difference of the materials that compose the positive and negative electrodes in the electrochemical reaction.
Almost all lithium-ion batteries work at?3.8 volts. In order to make current flow from the charger to the battery, there must be a potential difference. Therefore battery chargers or USBs for almost all smartphones provide a voltage of?5V.
Cut-off Voltage
The cut-off voltage is the minimum allowable voltage. It is this voltage that generally defines the “empty” state of the battery.
Li-ion battery has a higher cut-off voltage of around 3.2 V. Its nominal voltage is between 3.6 to 3.8 V; its maximum charging voltage can go to 4– 4.2 V max. The Li?ion can be discharged to 3V and lower; however, with a discharge to 3.3V (at room temperature), about 92–98% of the capacity is used. Importantly, particularly in the case of lithium-ion batteries used in the vast majority of portable electronics today, a voltage cut-off below 3.2V can lead to chemical instability in the cell, resulting in a reduced battery lifetime.
Capacity
The coulometric capacity is the total Amp-hours available when the battery is discharged at a certain discharge current from 100% SOC to the cut-off voltage.
Almost all lithium-ion batteries work at?3.8 volts. Lithium-ion 18650 batteries generally have capacity ratings from?2,300 to 3,6
0 mAh.
C-rate of Battery
C-rate is used to express how fast a battery is discharged or charged relative to its maximum capacity. It has units?h?1. A 1C rate means that the discharge current will discharge the entire battery in 1 hour.
Most li-ion batteries can only withstand a maximum temperature of 60°C and are recommended to be charged at a maximum of 45°C under a?0.5C charge rate. C rating for a 18650 battery is?usually 1C, meaning we can consume a maximum of 2.85A from the battery.
Self-discharge
Batteries gradually self-discharge even if not connected and delivering current. This is due to non-current-producing “side” chemical reactions that occur within the cell even when no load is applied.
Li-ion rechargeable batteries have a self-discharge rate typically stated by manufacturers to be?1.5–2% per month. The rate increases with temperature and state of charge.
Degradation
Some degradation of rechargeable batteries occurs on each charge-discharge cycle. Degradation usually occurs because electrolyte migrates away from the electrodes or because active material detaches from the electrodes.
Most modern 18650 lithium-ion batteries, which are common for laptop batteries, have a typical cycle life of?300 – 500?(charge, discharge cycles). LFP batteries offer cycle life, which ranges from 2,700 to more than 10,000 cycles depending on conditions.
Degradation of Lithium-ion Batteries due to Cycling
Some degradation of rechargeable batteries occurs on each charge-discharge cycle. Degradation usually occurs because electrolyte migrates away from the electrodes or because active material detaches from the electrodes. Manufacturers’ datasheet typically uses the word “cycle life” to specify lifespan in terms of the number of cycles to reach 80% of the rated battery capacity. Following the manufacturer’s recommendations is necessary to avoid danger or premature capacity degradation.
In lithium-ion batteries, degradation and capacity fade are generally attributed to the growth of the solid electrolyte interface (SEI). The solid electrolyte interface is created due to reactions between the electrodes and the electrolyte. These reactions form a film that hinders lithium ions from reacting with the electrodes, and as this film grows in thickness, the cell degrades.?
Low-capacity NiMH batteries (1,700–2,000 mA·h) can be charged some 1,000 times, whereas high-capacity NiMH batteries (above 2,500 mA·h) last about 500 cycles. NiCd batteries tend to be rated for 1,000 cycles before their internal resistance permanently increases beyond usable values. Fast charging increases component changes, shortening battery lifespan. If a charger cannot detect when the battery is fully charged, then overcharging is likely damaging.
Most modern 18650 lithium-ion batteries, which are common for laptop batteries, have a typical cycle life of 300 – 500 (charge, discharge cycles). When in C-rate or high DOD situations, this can decrease substantially to 200 cycles.
In real-life applications, Li-ion cells experience accelerated degradation due to certain stress factors. Stress factors such as deep DODs, elevated C-rates, high or low temperatures, and operating at high SOCs can have a negative impact on the cell capacity and cause accelerated degradation.
Depth of Discharge
Depth of discharge is a measure of how much energy has been withdrawn from a battery and is expressed as a percentage of full capacity. For example, a 100 Ah battery from which 40 Ah has been withdrawn has undergone a 40% depth of discharge (DOD).
For lithium-ion batteries, the cycle life of a cell strongly depends on the DOD. The loss of lithium ions and active electrode material is higher for larger DOD cycles. At high DODs, additional degradation mechanisms can occur, resulting in the decomposition and dissolution of cathode material and capacity fading.
ADVANTAGES OF LITHIUM-ION BATTERIESyoutube
The advantages of LIBs include:
LIB electrochemistry is more efficient than other secondary batteries
There are numerous electrode and electrolyte combination options available with LIBs. Research and development in new cathode, anode, electrolyte, and electrochemical activities in LIBs has advanced significantly during the last 20 years. Since invention of LIBs, theoretical and experimental research has boosted power density, energy density, and life expectancy. For instance, the LIB has roughly twice the energy density of a typical Ni–Cd battery.
Low self-discharge rate
Even in the absence of load, a battery experiences chemical reactions that induce self-discharge, which is a certain charge loss. The LIB exhibits only a small amount of self-discharge, which is only about 5% in the first four hours after charging and thereafter only 1–2% per month. The self-discharge of a LIB battery is half that of a Ni–Cd battery.
Easy maintenance
The LIB does not need regular active maintenance like lead–acid batteries, and it has a portable design and one-time purchase warranty. Its cycle life is ten times greater than that of lead–acid batteries, and over 2000 cycles, it performs at about 80% of rated capacity.
Environmentally friendly and sustainable
In comparison to lead–acid and Ni–Cd batteries, LIBs contain comparatively few hazardous elements. Additionally, LIBs can be charged quickly and efficiently at any place with basic chargers, whereas lead–acid batteries need to be charged over an extended period of time.
In comparison to a lead–acid battery, the LIB offers more energy in only half the mass. As a result, it uses less material, is smaller, and is better suited for easy installation. For instance, a typical LIB has a storage capacity of 150 watt-hours per kg, compared to perhaps 100 watt-hours for nickel–metal hydride batteries. However, a lead–acid battery can store only 25 watt-hours per kg. A lead–acid battery must therefore weigh 6 kg in order to store the same amount of energy as a 1 kg LIB.
No memory effect
If a battery is partially discharged before being recharged, then it will deliver the amount of energy which is used during partial discharge, this is known as the 'memory effect', or 'lazy battery effect'. Lithium-ion batteries don't suffer from memory effect, which means that there is no need to completely discharge before recharging.
High cell voltage
A single cell of a LIB provides a working voltage of about 3.6 V, which is almost two to three times higher than that of a Ni–Cd, NiMH, and lead–acid battery cell.
Good load characteristics
The LIB provides steady voltage under any load condition. It has good working performance until its reasonable discharge, i.e. successfully retains constant voltage per cell.
High energy and power density
Lithium is a highly reactive element, meaning that a lot of energy can be stored in its atomic bonds, which translates into high energy density for lithium-ion batteries. Hence, it can be used in adequate sizes for applications from portable electronic devices, smartphones, to electric vehicles. The use of electrode materials with an effective electrochemical surface area provides reasonable energy and power density. While for applications like electric vehicles, there is an ongoing requirement for batteries with higher power density, and therefore more efforts in this regard are still in progress.
Numerous choices for electrode materials
As a result of global research and development efforts, several classes of nanostructured materials, including lithium metal oxides, chalcogenides, silicates and phosphates, with different chemical compositions, crystal structures, and higher surface/volume ratios have been revealed to provide additional sites for Li storage. This demonstrates an improvement in the electrochemical performance of LIBs.
Long cycle life
Numerous factors can affect a battery's cycle life. Compared to lead–acid batteries, under standard conditions, with minimal value of DOD, a LIB has a greater cycle life of about 1000–1500 charge/discharge cycles. Also, other secondary batteries have the problem of corrosion due to high DOD.
High round trip efficiency
Round trip efficiency is a measure of the energy retention of a battery after its fully charged state. Due to fewer losses in storage or self-discharge, the LIB has a higher round trip efficiency of about 95% compared to other batteries.
DISADVANTAGES OF LITHIUM-ION BATTERIES
Disadvantages
Despite its benefits, the LIB, like other batteries, has several shortcomings and challenges, including:
LITHIUM-ION BATTERIES APPLICATIONS
Pacemakers
Rechargeable lithium batteries have become common in pacemakers because they provide long life, low drain current, high energy density, and desirable voltage characteristics. Pacemaker Li-ion batteries have a typical lifespan of seven to eight years and often weigh less than 30 grams. Primary lithium cells experience a 10% loss of capacity over five years.
Digital Cameras
For a digital camera to function effectively, it requires a robust and high-energy-density power source. So most mirrorless cameras and DSLRs take advantage of the many benefits of using lithium-ion batteries as a power source.
These rechargeable Li-ion battery packs are much smaller than other battery types and, generally, have a much larger power capacity and superior battery performance.
Many camera brands stay loyal to a specific Li-ion battery design throughout many generations of cameras. This means that even when users upgrade their digital camera, they can use the same lithium-ion battery.
Personal Digital Assistants, Smartphones, and Laptops
Rechargeable lithium-ion batteries have become incredibly popular for smartphones, laptops, personal digital assistants (PDAs), and other portable electronic devices. There are many reasons why so many manufacturers have adopted rechargeable Li-ion batteries, for example:
Watches
Li-ion batteries used in watches are small. Despite their size, their 3 Volt capacity has a lifespan of as much as a decade in a low-drain watch.
Portable Power Packs
The benefits of rechargeable lithium-ion batteries are very familiar to anyone with a smartphone or one of the latest lightweight laptop computers. Compared to lead-acid batteries, lithium-ion batteries are smaller in size and lighter.
In addition, they can withstand more movement and changes in temperature and still maintain power delivery while in use.
Charging of Li-ion batteries can be done much quicker than a lead-acid battery. Thanks to custom Li-ion battery options, it’s now possible to swap out existing battery technology for more efficient and longer-lasting portable power packs.
Personal Mobility
A rechargeable lithium-ion-powered personal mobility scooter can go a long way. The range can be as much as twelve miles.
One of the main benefits of using lithium-ion batteries is they are lightweight. Users can easily carry the battery indoors for recharging.
In addition, lithium batteries are the perfect green alternative to lead-acid batteries, are longer lasting, and charge faster. Less weight also means an extended travel range and less mechanical wear and tear.
Solar Energy Storage
Solar power is something the world is looking to rely on more and more. In the United States alone, it is predicted that solar will provide 20% of the country's energy needs by the year 2050.
Lithium batteries are ideal for energy storage and can be used to store the excess power produced by solar panels. Let’s face it, even in the middle of the desert, there are days when the sun doesn’t shine. There are also going to be times when the solar equipment needs repairing. Using lithium-ion batteries for energy storage means there are no occasions when you find yourself left in the dark.
One of the reasons lithium batteries are used for solar energy storage is that they match the panels in how they charge. How fast they charge is another reason. Lithium batteries require low-resistance charging, which is what solar panels produce.
The fact that these batteries charge so quickly also allows users to maximize the potential energy storage of solar power for every minute of sunlight available.
Uninterrupted Power Supply (UPS) or Emergency Power Backup
Even in today’s modern world, there are issues with power instability – or worse – power loss. Lithium technology is commonly used for emergency power backup or UPs battery models.
Using a lithium battery for backup is different from relying on a generator or other backup energy system. It will provide almost instant power, which is crucial if critical equipment needs to be connected to a constant power supply.
Lithium batteries and the backup power they can provide benefit a range of critical equipment such as medical technology, communication technology, and computers.
Surveillance and Alarm Systems
A hard-wired electricity supply is no longer essential if you want to monitor remote locations, a fleet of vehicles, a temporary location, or various job sites. You can use Li-ion batteries instead to power an alarm or surveillance system in remote or difficult locations with no access to an electrical grid.
The qualities that make Li-ion batteries so useful are their small size, long life, and the fact that they don’t lose power by way of self-discharge when the system they power is inactive. The low self-discharge rate of a typical lithium-ion battery is ten times lower than a traditional lead-acid battery. Lithium batteries are the ideal solution if a system is not continually in use.
Electric Vehicles and Mobility Scooters
People with mobility issues have found new freedom thanks to rechargeable lithium-ion batteries. They can be used in a variety of ways to make lives easier. Millions of people around the world now depend on stairlifts, electric wheelchairs, and mobility scooters.
The reliability of a Li-ion battery and the mobility technology it powers allows them to live a more independent life.
As in their many other applications, lithium batteries are lightweight, have a longer life span, and have a low self-discharge rate. They also offer an extended run time, size customization, and fast charging. Hence the popularity of large lithium-ion batteries for electric automobiles.
Golf Carts and Trolleys
While lead-acid batteries were the traditional choice for electric vehicle applications like golf carts and trolley makers, more are now choosing lithium batteries. As long as your electric golf trolley uses the same energy connector, you can swap out the lead-acid battery for a lithium-ion battery.
You can expect Li-ion battery systems to have a long cycle life of between 1,000 and 2,000 charging cycles. How long the battery lasts depends on how frequently you play golf and how often you charge the battery.
If you play golf twice a week, that’s 2 x 52 weeks = 104 charging cycles per year. This means you can expect a lithium-ion battery to last a minimum of ten years.
SUMMARY AND CONCLUSION
What is lithium ion battery chemistry
A lithium-ion battery relies on lithium ions in its electrochemistry. Simple oxidation-reduction processes take place as part of lithium-ion battery chemistry.
The components of a lithium-ion battery include cathode electrode, anode electrode, separator and electrolyte. The cathode is where reduction occurs, whereas the anode is an oxidation site. The electrolyte is a lithium salt in an organic solvent, whereas the cathode is a substance comprising lithium, and the anode is a compound that contains carbon.
How does lithium ion battery chemistry work
The lithium-ion battery chemistry operates according to redox chemistry principles. The anode, the cathode, and the electrolyte are the three components that take part in redox reactions in a lithium-ion battery. Lithium ions may go into both the anode and the cathode.
During discharge in a lithium ion cell, the lithium ion is evacuated from the cathode and deposited into the anode, releasing the energy collected there. When the cell is charged, the opposite occurs. The micro-permeable barrier, separator that isolates the anode from the cathode may be able to let the lithium ions flow through because of their tiny size.
Due to lithium’s small size, lithium-ion batteries can store large amounts of charge and operate at high voltage levels.
Chemical materials in lithium ion battery cathode
Within the Li-ion market around the word, a variety of cathode materials are available. Cobalt was the cathode’s primary active material at first. Today, nickel is commonly used. Cathode materials must have exceptionally high degrees of purity and be completely devoid of undesirable metal impurities for the efficiency of lithium-ion battery chemistry.
Cathode chemicals are the primary components controlling the differences in composition when constructing cathode electrodes for battery cells. Cobalt, nickel, and manganese usually make up the cathode components, which together create a multi-metal oxide material in which lithium is introduced.
Various cathode chemicals are used in lithium-ion batteries to meet the demands of various users for higher energy density and load-bearing capacity.
What are the materials used in lithium ion battery anode
The anode material used in most lithium-ion batteries is graphite powder. Materials for making graphite anodes are either synthesized artificially or extracted from the earth and put through a lot of processing before being put onto the copper foil. Graphite anodes are reasonably inexpensive, incredibly light, absorbent, and robust. Graphite anodes also satisfy the power requirements of the majority of popular Li-ion cathodes.
Graphite can reversibly deposit lithium ions through its multilayer films, so graphite is often used as the active material in anodes. Batteries with appropriate electrodes are needed if this reversible electrochemical capability is to be maintained for multiple cycles.
However, the graphite surface must match the chemistry of a lithium-ion battery in order to be used as a anode.
Performance of different cathodes in lithium ion battery chemistry
LFP and NMC are two of the mainstream cathode materials being used in lithium ion battery chemistry. Lithium Iron Phosphate (LFP) is one of the most popular and commonly used cathodes in lithium ion battery chemistry. It doesn’t use nickel or cobalt, which makes it cost-effective and safer.
However, improvements are being made to enhance LFP’s performance. And now, many battery companies are developing lithium iron manganese phosphate batteries, which combine the advantages of ternary and lithium iron while ensuring safety and energy density.
Nickel manganese cobalt (NMC) is a popular cathode material in Li-ion batteries. It is preferred for many automobiles because it offers good performance, high specific energy, and low self-heating. The NMC and LFP battery chemistries behave similarly, have comparable performance traits, and carry out their functions in an identical manner.
However, LFP is the preferred option due to its affordability and safety.
What is the difference between LFP and NMC batteries
LFP and NMC are the two most common batteries used in all-electric vehicles today. Both of these battery types are used in various applications, but the electric car business, which uses the most lithium batteries, is the most fiercely competitive.
The primary difference between NMC and LFP is that while LFP uses chemistry based on lithium iron phosphate, NMC uses a cathode material based on nickel, manganese, and cobalt oxide.
Due to different materials, their respective temperature resistance performance is also different, ternary lithium battery is not resistant to high temperature, lithium iron phosphate are not resistant to low temperature.
What is the safest lithium ion battery chemistry
LFPs are among the safest lithium ion battery chemistry available. Lithium iron phosphate batteries are incredibly safe and highly stable because the materials used in them have little resistance.
What makes it the preferable battery for most applications? The built in BMS avoid overcharge and undercharge to safeguard the battery and extend its lifespan.
The cycle life of lithium ion batteries like 12v lithium-ion battery has 4,000 cycles. Moreover, LFP battery chemistry also offers excellent thermal stability and can operate in harsh weather.
What battery chemistry does Tesla use
Tesla will switch all its standard-range vehicles internationally to Lithium Iron Phosphate (LFP) battery chemistry. Every single Tesla single-motor rear-wheel drive vehicle will include LFP battery cells. Safety is one of the primary considerations for Tesla to switching to LFP battery chemistry.
New development of lithium ion battery chemistry material
Advances in sustainable development, energy density, power density, lifespan, are necessary for the new development of lithium ion battery chemistry that is reliable. There are still plenty of prospects for advancement in the next-generation cathode market.
This presents a highly complex improvement task. Advancements in cathode chemistry design and development, synthetic techniques, and cost savings techniques can give the performance gains necessary for the short term and the long run.
Conclusion
Consider the battery’s performance and the cost over its lifetime while selecting the ideal battery.
In this scenario, lithium iron phosphate (LFP) batteries are the best option due to their lithium-ion chemistry’s longer lifespan and safer functioning. It stands to reason from the perspective of operational effectiveness and the enhanced safety factor provided.