What is the basic knowledge of lithium battery?
MSN Battery
We focus on Lithium battery, LiFePO4 battery, Solar battery, gel battery, UPS battery and so on.
Below we will learn in 10 points what is the basic knowledge of lithium battery?
Lithium batteries are mainly composed of two large parts, the battery cell and the protective plate PCM (Power batteries are generally called battery management systems BMS). The battery cell is equivalent to the heart of the lithium battery, and the management system is equivalent to the brain of the lithium battery.
The battery core is mainly composed of positive electrode material, negative electrode material, electrolyte, separator, and casing, while the protective board is mainly composed of a protection chip (or management chip), MOS tube, resistor, capacitor, and PCB board.
Lithium batteries can be divided into two major categories: disposable non-rechargeable batteries and secondary rechargeable batteries (also known as batteries).
Non-rechargeable batteries such as lithium manganese dioxide batteries and lithium-sulfite batteries.
Secondary rechargeable batteries can be divided into the following categories according to different situations.
1. According to appearance: prismatic lithium battery and cylindrical lithium battery (such as 32700);
2. According to packaging materials: aluminum case lithium battery, steel case lithium battery, soft pack battery;
3. According to the cathode material: lithium cobalt oxide (LiCoO2), lithium manganate (LiMn2O4), ternary lithium (LiNixCoyMnzO2), lithium iron phosphate (LiFePO4);
4. According to the electrolyte state: lithium-ion battery (LIB) and polymer battery (PLB);
5. Divided by use: energy storage batteries and power batteries.
6. According to performance characteristics: high-capacity batteries, high-rate batteries, high-temperature batteries, low-temperature batteries, etc.
Advantages: high voltage platform, high energy density (lightweight, small size), long service life, and environmentally friendly.
Disadvantages: The price is relatively high, the temperature range is relatively narrow, and there are certain safety hazards (a protection system is required).
1. Capacity
Refers to the amount of electricity that can be obtained from lithium batteries under certain discharge conditions.
The formula for power is Q=I*t, and the unit is Coulomb. The capacity unit of the battery is specified as Ah (ampere-hour) or mAh (milliamp-hour), which means that a 1Ah battery can be discharged with a current of 1A when fully charged. Leave for 1 hour.
In the past, the batteries of old NOKIA mobile phones (like BL-5C) were generally 500mAh. Nowadays, smartphone batteries are 800~1900mAh, electric bicycles are generally 10~20Ah, electric cars are generally 20~200Ah, etc.
2. Charge-Rate/Discharge-Rate
Indicates how much current to charge and discharge, generally calculated as a multiple of the nominal capacity of the battery, generally called several C. For example, for a battery with a capacity of 1500mAh, it is stipulated that 1C=1500mAh. If it is discharged at 2C, it is discharged at a current of 3000mA. If it is charged and discharged at 0.1C, it is charged and discharged at a current of 150mA.
3. Voltage
The voltage of the battery generally refers to the nominal voltage (also called the rated voltage) of the lithium battery. The nominal voltage of an ordinary lithium battery is generally 3.7V, and we also call its voltage platform 3.7V.
When the capacity of the battery is 20~80%, the voltage is concentrated at about 3.7V (about 3.6~3.9V), the capacity is too high or too low, and the voltage changes greatly.
4. Energy/Power
The battery is discharged according to a certain standard, and the energy (E) that the battery can release is in Wh (watt-hour) or KWh (kilowatt-hour), 1KWh=1 kilowatt-hour.
E=U*I*t is also equal to the battery voltage multiplied by the battery capacity.
领英推荐
The formula for power is, P=U*I=E/t, which represents the energy that can be released per unit time. The unit is W (watt) or KW (kilowatt).
For a battery with a capacity of 1500mAh, the nominal voltage is generally 3.7V, so the corresponding energy is 5.55Wh.
5. Resistance
Since it cannot be equivalent to an ideal power supply when charging and discharging, it has a certain internal resistance. Internal resistance consumes energy, of course, the smaller the internal resistance, the better.
The unit of battery internal resistance is milliohms (mΩ).
Generally, the internal resistance of a battery is composed of ohmic internal resistance and polarization internal resistance. The size of the internal resistance is affected by the material, manufacturing process, and structure of the battery.
6. Cycle Life
A battery charge and discharge once is called a cycle, and the cycle life is an important indicator to measure the battery life performance.
IEC standards stipulate that mobile phone lithium batteries should be discharged to 3.0V at 0.2C and charged to 4.2V at 1C. After repeat??cycles of 500 times, the battery capacity should remain at more than 60% of the initial capacity. That is to say, the cycle life of a lithium battery is 500 times.
The national standard stipulates that after 300 cycles of cycle life, the capacity should maintain 70% of the initial capacity. If the battery capacity is less than 60% of the initial capacity, it should generally be considered for scrap disposal.
7. Depth of discharge (DOD: Depth of Discharger)
Defined as the percentage of the capacity released by the battery to the rated capacity.
Generally, the deeper the discharge depth of lithium batteries, the shorter the battery life.
8. Cut-Off Voltage
The termination voltage is divided into charge termination voltage and discharge termination voltage, that is to say, the voltage at which the battery cannot continue to charge or discharge. Continuing to charge or discharge at the termination voltage has a great impact on the life of the battery.
The charge termination voltage of lithium batteries is generally 4.2V, and the discharge termination voltage is 3.0V.
Deep charging or deep discharging of lithium batteries exceeding the cut-off voltage is strictly prohibited.
9. Self-discharge rate (Self-Discharge)
Refers to the rate of decline of battery capacity during storage, expressed as the percentage of capacity decline per unit of time.
The self-discharge rate of general lithium batteries is 2%~9%/month.
10. SOC (State of Charge)
Refers to the percentage of the remaining power of the battery to the total power that can be discharged, 0~100%. Reflects the remaining battery power.
There are certain differences in the process flow of different batteries and different manufacturers. The detailed process flow will be very complicated. The basic process flow is listed below, including the process flow of battery cell production and the process flow of PACK production.
The battery cell production process mainly includes pole piece manufacturing, battery cell production, battery assembly, liquid injection, formation, sorting, and other processes.
From batching to winding, the positive and negative electrodes are done in separate workshops at the same time. After the positive and negative electrodes are ready, the subsequent processes are done together.
Different quality inspection and QA links will be inserted in the middle.
#lifepo4battery #lithiumbattery #lifepo4 #solarbattery #energystoragebattery #battery #batterymanufacturer #batteryfactory #MSNbattery #solarbatteries #lfp #batteries #lithiumionbatteries #lithiumbatteryknowledge