The advantage of new energy vehicles lies in their lower carbon footprint and greater environmental friendliness compared to gasoline-powered vehicles. They utilize unconventional automotive fuels as their power source, such as lithium batteries and hydrogen fuel. Lithium-ion batteries have a wide range of applications, including not only new energy vehicles but also mobile phones, laptops, tablets, power banks, electric bicycles, and power tools.
However, the safety issues of lithium-ion batteries should not be underestimated. Numerous incidents have shown that improper charging or excessively high ambient temperatures can easily cause lithium-ion batteries to spontaneously combust or explode, which has become the biggest pain point in the development of lithium-ion batteries.
While the inherent properties of lithium batteries dictate their "flammable and explosive" nature, it is not entirely impossible to mitigate these risks and ensure safety. With continuous advancements in battery technology, both mobile phone manufacturers and new energy vehicle companies can ensure battery safety and prevent explosions or spontaneous combustion through effective battery management and thermal management systems.
1. Improve the safety of the electrolyte.
The electrolyte exhibits high reactivity with both the positive and negative electrodes, especially at high temperatures. Therefore, improving the safety of the electrolyte is one of the most effective methods to enhance battery safety. Adding functional additives, using novel lithium salts, and employing novel solvents can effectively address the safety hazards associated with the electrolyte.
Based on their different functions, additives can be mainly divided into the following categories: safety protection additives, film-forming additives, positive electrode protection additives, lithium salt stabilizing additives, lithium precipitation promoting additives, current collector corrosion prevention additives, and wettability enhancement additives.
2. Improve the safety of electrode materials
Lithium iron phosphate and ternary composite materials are considered low-cost and "safe" cathode materials, and have the potential for widespread application in the electric vehicle industry. A common method to improve the safety of cathode materials is coating modification, such as coating the cathode material with metal oxides. This can prevent direct contact between the cathode material and the electrolyte, suppress phase transitions in the cathode material, improve its structural stability, and reduce the disorder of cations in the crystal lattice, thereby reducing heat generation from side reactions.
For anode materials, since their surface is often the part most prone to thermochemical decomposition and heat release in lithium-ion batteries, improving the thermal stability of the SEI film is a key method to improve the safety of anode materials. The thermal stability of anode 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, many safety protection measures adopted in commercial lithium-ion batteries, such as setting up battery safety valves, thermal fuses, connecting components with positive temperature coefficients in series, using heat-sealed diaphragms, loading dedicated protection circuits, and dedicated battery management systems, are also means to enhance safety.
