What are the five major trends in the development of lithium battery electrolyte technology?

The electrolyte is an Ionic conductor that acts as a conduction between the positive and negative poles of the battery. It is composed of lithium electrolyte salts, high-purity organic solvents, and necessary additives and other raw materials in a certain proportion. It plays an important role in the energy density, power density, wide temperature application, cycle life, and safety performance of batteries.

Lithium battery is composed of shell, positive electrode, negative electrode, electrolyte and diaphragm. The electrode material is undoubtedly the focus of attention and research. But at the same time, the electrolyte is also an aspect that can not be ignored. After all, the electrolyte that accounts for 15 % of the battery cost does play a crucial role in the battery's energy density, power density, wide temperature application, cycle life, and safety performance. role.

The electrolyte is an Ionic conductor that acts as a conduction between the positive and negative poles of the battery. It is composed of lithium electrolyte salts, high-purity organic solvents, and necessary additives in a certain proportion. As the application of lithium batteries is more and more extensive, the requirements of lithium batteries for their electrolytes must also be different. Next, the small series on the electrolyte development trend of lithium key raw material-electrolyte.

1, high ratio energy electrolyte

The pursuit of high-specific energy is currently the largest research direction of lithium ion batteries. Especially when mobile devices occupy more and more proportion in people's lives, endurance has become the most critical performance of batteries.

In the future, the development of high-energy density batteries must be Gaodianya positive pole and Silicon negative pole. Negative Silicon has a huge volume of grams and is concerned by people. However, due to its own swelling effect, it can not be applied. In recent years, the research direction has changed to a Silicon negative electrode, which has a relatively high volume of grams and a small volume change. Different membrane additives have different cyclic effects on the negative electrode of silica.

2, high power electrolyte

At present, it is difficult for commercialized lithium electron batteries to achieve high magnification and continuous discharge. The main reason is that the battery ears are hot and the internal resistance causes the overall temperature of the battery to be too high and it is prone to thermal runaway. Therefore, it is necessary for the electrolyte to be able to suppress the overheating of the battery without maintaining a high conductivity. And for the power cell, fast charging is also an important direction for the development of electrolytes.

High-power batteries not only require high solid phase diffusion, nanocrystallization to make ion transfer paths short, control electrode thickness and compaction, but also higher requirements for electrolytes: 1, high dissociation electrolyte salt; 2, solvent compound-viscosity is lower; 3, interface control-lower membrane impedance.

3, wide temperature electrolyte

Batteries are prone to decomposition of the electrolyte itself at high temperatures and the side reaction between the material and the electrolytic liquid is intensified. At low temperatures, electrolyte salt precipitation and negative electrode SEI membrane impedance may increase exponentially. The so-called wide temperature electrolyzer is to make the battery have a broader working environment. The following figure shows the boiling point contrast and solidification contrast of various solvents.

4, safety electrolytes

The safety of the battery is mainly reflected in the combustion or even explosion. First of all, the battery itself is flammable. Therefore, when the battery is overcharged, over-discharged, and short-circuited, when it receives external acupuncture and extrusion, when the external temperature is too high, Could cause a safety accident. Therefore, flame retardant is one of the main directions in the study of safe electrolytes.

The flame retardant function is obtained by adding flame retardant additives in conventional electrolytes. Phosphorus or halogen flame retardants are generally used, and the price of flame retardant additives is reasonable and does not damage the performance of electrolytes. In addition, the use of room temperature Ionic liquids as electrolytes has also entered the research phase, which will completely exclude the use of flammable organic solvents in batteries. Moreover, Ionic liquids have the characteristics of extremely low vapor pressure, good thermal stability/chemical stability, and non-flammable, which will greatly improve the safety of lithium ion batteries.

5, long cycle electrolyte

Since there are still major technical difficulties in the recovery of lithium batteries, especially power batteries, improving the battery life is a way to alleviate this situation.

There are two main ideas for the study of long-cycle electrolytes. One is the stability of electrolytes, including thermal stability, chemical stability, and voltage stability. The second is the stability of other materials, requiring stability with electrode formation, no oxidation with the diaphragm, and no corrosion with the collection fluid.

The page contains the contents of the machine translation.