[SMM Analysis] Do You Know These Electrolyte Facts?

SMM March 13 News: 

Lithium battery electrolyte serves as the carrier for ion transmission within the battery. It facilitates ion conduction between the positive and negative electrodes of lithium batteries, ensuring the advantages of high voltage and high specific energy in lithium-ion batteries. Electrolyte is generally prepared under specific conditions and in specific proportions using high-purity organic solvents, electrolyte lithium salts, necessary additives, and other raw materials. Currently, lithium battery electrolytes are mainly categorized into electrolyte for ternary power batteries, electrolyte for LFP ESS, electrolyte for LFP power batteries, electrolyte for LCO batteries, and electrolyte for LMO batteries. They are typically formulated using high-purity organic solvents, solutes, and necessary additives under specific conditions and in specific proportions.

The solutes mainly include LiPF6 and lithium bis(fluorosulfonyl)imide. LiPF6 is synthesized through a series of reactions involving lithium carbonate, phosphorus pentachloride, and anhydrous hydrogen fluoride. It exhibits moderate ionic transference number, moderate dissociation constant, excellent oxidation resistance, and good aluminum foil passivation capability in commonly used organic solvents. Additionally, it is compatible with various cathode and anode materials, making it the most widely used electrolyte lithium salt in commercial lithium-ion batteries. Lithium bis(fluorosulfonyl)imide, due to its superior conductivity, thermal stability, and high/low-temperature performance, holds significant advantages in the field of lithium battery additives.

The solvents mainly include ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and propylene carbonate (PC). Among these, EC and PC are cyclic carbonates, with EC having a higher dielectric constant and better chemical stability. DEC, DMC, and EMC are linear carbonates, with DMC being widely used in lithium batteries due to its strong dissolving ability and excellent low-temperature charge-discharge performance. The demand for lithium battery electrolyte solvents is primarily concentrated on DMC, EC, EMC, and DEC.

Lithium battery additives are an economical and practical method to improve the performance of lithium-ion batteries. By adding a small amount of additives to the electrolyte, specific battery performance metrics, such as reversible capacity, cycle performance, C-rate performance, and safety performance, can be enhanced. The selection criteria for additives include high solubility in organic solvents, no harmful side reactions with other battery components, and low cost. Commonly used additives in lithium battery electrolytes include fluoroethylene carbonate (FEC) and vinylene carbonate (VC). FEC is known for its excellent SEI film-forming properties, creating a compact structural layer without increasing impedance, effectively preventing further decomposition of the electrolyte and improving its low-temperature performance. VC, with its excellent high/low-temperature performance and anti-swelling properties, is often used as a new-type organic film-forming additive and overcharge protection additive for lithium-ion batteries, enhancing battery capacity and cycle life.

From smartphones to EVs, from household ESS to large-scale power grids, electrolytes, as an indispensable part of batteries, quietly support every advancement in modern energy technology. With the rapid development of the new energy industry, electrolyte technology continues to innovate, potentially bringing more efficient, safer, and environmentally friendly energy solutions in the future. Let us pay attention to electrolytes and look forward to them injecting more vitality into our green future!

SMM New Energy Research Team

Cong Wang 021-51666838

Rui Ma 021-51595780

Disheng Feng 021-51666714

Ying Xu 021-51666707

Yanlin Lü 021-20707875

Yujun Liu 021-20707895

Xiaodan Yu 021-20707870

Xianjue Sun 021-51666757

Zhicheng Zhou 021-51666711

He Zhang 021-20707850