Are you still struggling to choose which type of battery to use?

Batteries, as an essential source of energy in modern life, often fascinate people with their internal structure and operating mechanisms. In the journey of exploring this complex system, we cannot ignore an important concept - internal resistance of the battery. Internal resistance not only affects the performance of the battery, but also directly relates to the battery's lifespan and safety. Today, we will delve into the main components of internal resistance of batteries: Ohmic resistance and polarization resistance.

One.Ohm's internal resistance

Let's start with the concept of ohmic resistance. Ohmic resistance can be further divided into ionic resistance, electronic resistance, and contact resistance.

Ionic resistance:?It refers to the resistance encountered by lithium ions when they pass through the battery. This process is mainly influenced by the positive and negative electrode materials, the separator, and the electrolyte.

Electronic resistance:?It concerns the resistance encountered by electron transmission, which is mainly affected by the contact between active substances and the collecting fluid, the characteristics of the active substance itself, the parameters of the electrodes, and the substrate of the collecting fluid.

Contact resistance: It is mainly formed by the contact between active material particles and between active material and collection fluid. The magnitude of this resistance is mainly influenced by the adhesion of positive and negative electrode slurries.

Two.Polarization internal resistance

Polarization internal resistance is a crucial concept in battery science and can generally be divided into three main types: ohmic polarization, electrochemical polarization, and concentration polarization.

First, let's talk about Ohmic polarization, which refers to the accumulation of local charges due to the presence of internal resistance when an external current flows through a battery, resulting in the current exceeding the resistance provided by Ohm's law itself.

Next, let's take a look at electrochemical polarization. This occurs in the reaction process at the electrode surface, when the rate of electron transfer exceeds the rate of electrochemical reaction, resulting in an accumulation of electrons.

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Lastly, there is concentration polarization which occurs when the ion transport rate is slower than the reaction rate on the electrode surface and in the solid phase, resulting in a concentration difference. This is a direct consequence of the material transfer process.

The internal resistance of a battery refers to the resistance encountered by current passing through the battery, usually expressed in the form of internal resistance (mΩAh). For commercial LFP batteries, the normalized range of internal resistance is roughly 35 to 70 mΩAh. Specifically, batteries from different manufacturers exhibit different values in this indicator.

Three.Summary of Lithium Battery Internal Resistance

When discussing the internal resistance of lithium-ion batteries, it is crucial to understand these three forms of polarization to comprehend their performance. Generally speaking, the internal resistance of lithium-ion batteries can be affected by various factors, including but not limited to the physical properties of battery materials, the composition of the electrolyte, and the battery's operating environment. Although the specific values may differ due to battery design and application conditions, understanding the nature of these polarization phenomena can help us gain a deeper understanding of the limiting factors of battery performance.

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