How to improve the safety of lithium-ion batteries?

The advantage of new energy vehicles is that they are more low-carbon and environmentally friendly than gasoline-fueled vehicles. It uses unconventional vehicle fuels as its power source, such as lithium batteries, hydrogen fuel, etc. Lithium-ion batteries are also used in a wide range of applications, including new energy vehicles, mobile phones, laptops, tablets, mobile power supplies, electric bicycles, power tools, etc.

However, the safety issues of lithium-ion batteries cannot be underestimated. Many accidents have shown that when people charge improperly or the ambient temperature is too high, it is very easy to cause spontaneous combustion and explosion of lithium-ion batteries. This has also become the biggest pain point in the development process of lithium-ion batteries.

Although the properties of lithium batteries themselves determine their fate of being “flammable and explosive”, it is not completely impossible to reduce risks and safety. With the continuous advancement of battery technology, whether it is a mobile phone company or a new energy vehicle company, through reasonable battery management systems and thermal management systems, batteries can ensure safety and will not explode or spontaneously ignite.

1. Improve the safety of electrolyte

There is a high reactivity between the electrolyte and the positive and negative electrodes, especially at high temperatures. In order to improve the safety of the battery, improving the safety of the electrolyte is one of the more effective methods. The potential safety hazards of the electrolyte can be effectively solved by adding functional additives, using new lithium salts, and using new solvents.

According to the different functions of additives, they can be mainly divided into the following categories: safety protection additives, film-forming additives, cathode protection additives, stabilizing lithium salt additives, lithium precipitation-promoting additives, current collector anti-corrosion additives, wettability-enhancing additives, etc.

2. Improve the safety of electrode materials

Lithium iron phosphate and ternary composite materials are considered to be low-cost, “excellent safety” cathode materials and may be widely used in the electric vehicle industry. For positive electrode materials, a common method to improve their safety is coating modification. For example, surface coating of the positive electrode material with metal oxide can prevent direct contact between the positive electrode material and the electrolyte, inhibit the phase change of the positive electrode material, and improve the safety of the positive electrode material. Its structural stability reduces the disorder of cations in the crystal lattice to reduce the heat generated by side reactions.

As for the anode material, since its surface is often the part in the lithium-ion battery that is most prone to thermochemical decomposition and heat release, improving the thermal stability of the SEI film is a key method to improve the safety of the anode material. The thermal stability of negative electrode materials can be improved through weak oxidation, metal and metal oxide deposition, polymer or carbon coating.

3. Improve battery safety protection design

In addition to improving the safety of battery materials, commercial lithium-ion batteries adopt many safety protection measures, such as setting up battery safety valves, hot-melt fuses, connecting components with positive temperature coefficients in series, using thermally sealed diaphragms, loading special protection circuits, and special battery management systems, etc., are also means to enhance security.