What is the electrolyte used for lithium-ion batteries?

What is the electrolyte used for lithium-ion batteries?

Lithium ion battery electrolyte is an important aspect that cannot be ignored, as it accounts for 15% of battery costs and indeed plays a crucial role in energy density, power density, wide temperature applications, cycle life, safety performance, and other aspects of the battery. Electrolyte is one of the four key materials of lithium-ion batteries, including the positive electrode, negative electrode, separator, and electrolyte. It is known as the "blood" of lithium-ion batteries and plays a role in conducting electrons between the positive and negative electrodes in the battery, ensuring that lithium-ion batteries obtain high voltage, high specific energy, and other advantages.

Lithium ion batteries are mainly composed of four parts: positive electrode material, negative electrode material, electrolyte, and separator. Electrolyte is one of the key raw materials for lithium-ion batteries and the blood of lithium-ion batteries. And lithium hexafluorophosphate (LIPF6) is the core material of lithium-ion battery electrolyte, commonly known as lithium salt, which is the electrolyte with high performance and usage.

At present, the pursuit of high specific energy is the research direction of lithium-ion batteries. Especially with the increasing proportion of mobile devices in people's lives, battery life has become the most critical performance of batteries.

Lithium battery electrolyte is the carrier for ion transport in batteries, mainly composed of high-purity organic solvents, electrolyte lithium salts, necessary additives and other raw materials. Electrolyte is generally composed of high-purity organic solvents, electrolyte lithium salts (lithium hexafluorophosphate, LiFL6), necessary additives and other raw materials, prepared in a certain proportion under certain conditions.

The safety of lithium-ion batteries is important in terms of combustion and even explosion. Firstly, the battery itself is flammable. Therefore, when the battery is overcharged, over discharged, or short circuited, when the battery is punctured and squeezed by the outside world, or when the outside temperature is too high, it may cause safety accidents. Therefore, flame retardants are an important research direction for safe electrolytes.

The selection of electrolytes has a significant impact on the performance of lithium-ion batteries. It must have good chemical stability, especially at high potentials and temperatures, and is not easily decomposed. It must have a high ion conductivity (>10-3 S/cm), and must be inert to the anode and cathode materials and cannot corrode them.

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

The direct use of metallic lithium as an anode material has a high reversible capacity, with a theoretical capacity of up to 3862mAh · g-1, which is more than ten times that of graphite material, and its price is also relatively low. It is considered the most attractive anode material for the new generation of lithium-ion batteries, but it will produce dendritic lithium. The use of solid electrolyte as ion conduction can suppress the growth of dendritic lithium, making it possible for metallic lithium to be used as an anode material.