Five major trends in the development of lithium battery electrolyte technology

The electrolyte is an ionic conductor for conduction between the positive and negative electrodes of the battery. It is composed of electrolyte lithium salts, high-purity organic solvents and necessary additives in a certain proportion. Application, cycle life, safety performance, etc. play a crucial role.

Lithium-ion batteries are composed of shells, positive electrodes, negative electrodes, electrolytes and separators, among which electrode materials are undoubtedly the focus of everyone's attention and research. But at the same time, the electrolyte is also an aspect that cannot be ignored. After all, the electrolyte, which accounts for 15% of the battery cost, does play a vital role in the battery's energy density, power density, wide temperature application, cycle life, safety performance, etc. character of.

The electrolyte is an ionic conductor for conduction between the positive and negative electrodes of the battery. It is made up of electrolyte lithium salts, high-purity organic solvents, and necessary additives in a certain proportion. As the application fields of lithium-ion batteries are becoming more and more extensive, the requirements of various lithium-ion batteries for their electrolytes are inevitably different.Also read:oem 300ah lithium

Pursuing high specific energy is the biggest research direction of lithium-ion batteries at present, especially when mobile devices account for more and more in people's lives, battery life has become the most critical performance of batteries.

Anode silicon has attracted attention due to its huge gram capacity, but it cannot be applied due to its own swelling application. In recent years, the research direction has been changed to silicon carbon anode, which has relatively high gram capacity and small volume change. Different The film-forming additives have different cycling effects on silicon carbon anodes

  1. High-power electrolyte

At present, it is difficult for commercial lithium electronic batteries to achieve high-rate continuous discharge. The important reason is that the battery tabs are seriously heated, and the internal resistance causes the overall temperature of the battery to be too high, which is prone to thermal runaway. Therefore, it is required that the electrolyte solution can restrain the battery from heating up too quickly while maintaining high conductivity. As for power lithium batteries, realizing fast charging is also an important direction for the development of electrolytes.Also read:odm lifepo4 battery 12v 400ah

High-power batteries not only put forward requirements for electrode materials such as high solid-phase diffusion, nano-sized ion migration paths, control of electrode thickness and compaction, etc., but also put forward higher requirements for electrolytes: 1. High dissociation electrolytes Salt; 2. Solvent recombination - lower viscosity; 3. Interface control - lower membrane impedance.

  1. Wide temperature electrolyte

At high temperatures, the battery is prone to self-decomposition of the electrolyte and intensified side reactions between materials and electrolyte components; while at low temperatures, electrolyte salt precipitation and negative electrode SEI film impedance may multiply. The so-called wide temperature electrolyte is to make the battery have a wider working environment. The following figure shows the boiling point comparison chart and solidification comparison chart of various solvents.

  1. Safety electrolyte

The safety of the battery is mainly reflected in the combustion and even explosion. First of all, the battery itself is flammable. Therefore, when the battery is overcharged, overdischarged, or short-circuited, when it receives external acupuncture or extrusion, when the external temperature is too high, may lead to safety incidents. Therefore, flame retardancy is an important direction in the research of safe electrolytes.Also read:odm 200 ah lithium manufacturer

The flame retardant function is obtained by adding flame retardant additives to the conventional electrolyte. Generally, phosphorus-based or halogen-based flame retardants are used. The flame retardant additives are required to be reasonably priced and not damage the performance of the electrolyte. In addition, the use of room temperature ionic liquids as electrolytes has also entered the research stage, which will completely exclude the use of flammable organic solvents in batteries. In addition, ionic liquids have the characteristics of extremely low vapor pressure, good thermal/chemical stability, and non-flammability, which will greatly improve the safety of lithium-ion batteries.

  1. Long-cycle electrolyte

Due to the current technical difficulties in the recycling of lithium-ion batteries, especially the recycling of power lithium batteries, improving the life of the battery is a way to alleviate this situation.

There are two important points in the research idea of ​​long-cycle electrolyte. One is the stability of the electrolyte, including thermal stability, chemical stability, and voltage stability; the other is the stability with other materials, which requires stable film formation with electrodes. There is no oxidation with the diaphragm, and no corrosion with the current collector.

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