Why does the capacity of lithium batteries decrease in winter?

Today, lithium battery manufacturers will take you to understand the reasons for the decline of lithium battery capacity in winter.

Lithium batteries have been widely used since they entered the market. The reason is that lithium batteries have the characteristics of large capacity, small size, and no pollution to the environment. However, in the low temperature environment, the application of lithium battery packs has problems such as low capacity, serious attenuation, and poor cycle rate performance.

According to reports, the discharge capacity of lithium batteries at -20 ° C is only about 31.5% of that at room temperature. The operating temperature of conventional lithium-ion batteries is between -20 and +55°C. But in aerospace, military and other fields, the battery is required to work normally at a temperature of -40°C or lower. Therefore, it is of great significance to improve the low-temperature performance of lithium batteries.

As far as its influencing factors and reasons are concerned, it is actually its electrolyte. The electrolyte has a great influence on the low temperature function of the lithium battery pack, and the composition and physical and chemical functions of the electrolyte have an important influence on the low temperature function of the battery. The problems faced by the battery at low temperature are: the viscosity of the electrolyte increases, the ion conduction speed becomes slower, the electron transfer speed of the external circuit does not match, the battery is severely polarized, and the charge and discharge capacity will drop sharply.

Especially during low-temperature charging, lithium ions easily form lithium dendrites on the surface of the negative electrode, resulting in battery failure. The low temperature function of the electrolyte is closely related to the conductivity of the electrolyte itself. Electrolytes with high conductivity transfer ions quickly and can exert greater capacity at low temperatures. The more the lithium salt in the electrolyte dissociates, the more migration times, and the higher the conductivity. The higher the conductivity, the faster the ion conducts, the less polarization it experiences, and the better the battery will function at low temperatures. Therefore, higher conductivity is a necessary condition for Li-ion batteries to perform well at low temperature.

Lithium battery manufacturer

The conductivity of the electrolyte is related to the composition of the electrolyte, and reducing the viscosity of the solvent is one of the methods to improve the conductivity of the electrolyte. The good fluidity of the solvent at low temperature is the guarantee of ion transport. The solid electrolyte film formed by the electrolyte in the negative electrode at low temperature is also the key to affecting the conduction of lithium ions, and RSEI is the main resistance to lithium batteries in low temperature environments.

According to the analysis of lithium battery manufacturers, the electrolyte is one of the low temperature characteristics that affect their lithium battery packs. But only the place where the battery is used, the place where the lithium battery pack is used is indispensable. Therefore, at low temperatures, we can only use low-temperature cells as low-temperature lithium battery packs. It can work at -40 degrees, but below that, our skills need to go a step further, but all with the advancement of technology. and development, the future can be expected.

Lithium battery cathode materials have many production processes, and each step of the manufacturing process has the danger of introducing metal foreign matter, which puts forward higher requirements on the equipment automation degree and on-site quality management level of material suppliers. However, due to cost constraints, the equipment of material suppliers has a low degree of automation, there are many interruption points in the manufacturing process, and uncontrollable dangers increase. Therefore, in order to ensure the stability of battery functions and avoid self-discharge, battery manufacturers must promote data suppliers to avoid the introduction of foreign metals from five aspects: human, machine, material, law, and environment.

The above is the relevant introduction brought by lithium battery manufacturers, I hope to be helpful to everyone.