CR2032 button cell

What is the purpose of CR2032 button cell pack diaphragm?

What is the purpose of CR2032 button cell pack diaphragm

The main components of lithium-ion batteries are positive and negative electrodes, diaphragms, organic electrolytes and battery shells. Among these structures, diaphragms are one of the key internal components.

The diaphragm mainly serves two purposes. The first purpose is to serve as an insulating layer. The existence of the insulating layer can effectively prevent the short circuit inside the CR2032 button cell caused by the contact between the positive and negative electrodes.

The second purpose is to serve as a semi-permeable layer. The semi-permeable layer can prevent larger molecules from passing through and allow small charged ions to pass through. This can increase the concentration difference near the positive and negative electrodes, which is conducive to the diffusion of ions, thereby improving the storage efficiency of lithium-ion batteries.

In addition to being useful for chemical reactions inside lithium-ion batteries, diaphragms are also useful for external physical reactions. For example, when a CR2032 button cell is squeezed or punctured by an external hard object, it is equivalent to adding an extra layer of insurance to the CR2032 button cell. Under normal circumstances, it can ensure that the CR2032 button cell pack will only swell instead of directly explode when it is impacted by external objects.

CR2032 button cell requirements for diaphragms

CR2032 button cell requirements for diaphragms include:

(1) Electronic insulation to ensure mechanical isolation of the positive and negative electrodes;

(2) A certain pore size and porosity to ensure low resistance and high ionic conductivity, and good permeability to lithium ions;

(3) Resistance to electrolyte corrosion and sufficient chemical and electrochemical stability, which is due to the fact that the solvent of the electrolyte is a highly polar organic compound;

(4) Good electrolyte wettability and strong liquid absorption and moisture retention ability;

(5) High mechanical stability, including puncture strength, tensile strength, etc., but the thickness is as small as possible;

(6) Good spatial stability and flatness;

(7) Good thermal stability and automatic shutdown protection performance;

(8) Small heat shrinkage, otherwise it will cause short circuit and trigger battery thermal runaway. In addition, power lithium-ion batteries usually use composite membranes, which have higher requirements for diaphragms.

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CR2032 button cell