Driven by the combined market demand for power lithium-ion batteries, energy storage lithium-ion batteries, and consumer lithium-ion batteries, the lithium-ion battery electrolyte market has broad development prospects. As the market expands, battery companies are placing higher demands on electrolyte manufacturers in terms of R&D capabilities, technological level, product control, production capacity, and raw material supply.
In terms of R&D capabilities and technology, battery companies are constantly pursuing faster charging performance, higher energy density, and higher safety performance. Electrolyte manufacturers need to delve into the interaction mechanisms between battery cathode and anode materials and electrolytes, develop new functional electrolyte solutions to respond quickly and promptly, and create matching products to meet the development speed of battery companies. Regarding quality, battery companies are placing increasingly stringent quality requirements on electrolyte manufacturers, necessitating continuous process optimization, improved quality control capabilities, and the development of more comprehensive electrolyte control procedures and testing methods to meet the needs of battery companies. In terms of production capacity and raw material supply, battery companies are making procurement demands on electrolyte manufacturers to match their capacity expansion needs. Electrolyte manufacturers need to achieve vertical integration in the lithium-ion battery materials field, forming a complete industrial chain encompassing organic solvents, additives, and electrolytes to avoid the impact of fluctuations in the demand for electrolyte raw materials on electrolyte supply and price fluctuations.
Therefore, through in-depth cooperation with battery companies, electrolyte manufacturers can leverage the technological, informational, and equipment advantages of battery companies to continuously improve the R&D level, quality level, and supply capacity of electrolytes and raw materials. Liquid batteries mainly consist of four parts: positive electrode material, negative electrode material, electrolyte, and separator. The electrolyte plays a role in conducting conductive ions between the positive and negative electrode materials inside the battery, and typically needs to meet performance characteristics such as high conductivity, wide operating temperature range, wide electrochemical window, good thermal stability, high chemical stability, and good safety. Electrolyte is a crucial raw material for lithium batteries, and its main components are solute, solvent, and additives. Among the three core materials of electrolytes—solutes (lithium salts), solvents, and additives—solutes account for the highest cost component. Based on different lithium salt solutes, electrolytes can be classified into lithium hexafluorophosphate (LiPF6) electrolytes, lithium tetrafluoroborate (LiBF4) electrolytes, lithium difluorosulfonylimide (LiFSI) electrolytes, lithium dioxalate borate (LiBOB) electrolytes, lithium difluorooxalate borate (LiDFOB) electrolytes, lithium difluorophosphate (LiPO2F) electrolytes, and lithium bis(trifluoromethanesulfonylimide) (LiTFSI) electrolytes. The upstream of China's lithium battery electrolyte industry chain mainly consists of suppliers of organic solvents (ethylene carbonate EC and dimethyl carbonate DMC), electrolyte lithium salts such as lithium hexafluorophosphate, and film-forming additives. The midstream of the industry chain comprises electrolyte manufacturers, such as those producing liquid electrolytes and solid electrolytes. Downstream in the industry chain are lithium battery manufacturers, whose applications include power batteries, 3C batteries, energy storage batteries, and supercapacitors.
Lithium-ion battery electrolyte is the carrier of ions in the battery. As an important component of the battery, lithium-ion battery electrolyte is generally composed of lithium salts and organic solvents. The electrolyte is one of the four key materials of lithium-ion batteries—positive electrode, negative electrode, separator—and is often referred to as the "blood" of the lithium battery. Today, we will give you a comprehensive introduction to the composition of lithium-ion battery electrolytes.
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I. What is lithium battery electrolyte?
The electrolyte in a lithium-ion battery is the carrier for ion transport within the battery. It is generally composed of lithium salts and organic solvents. The electrolyte acts as a conductor of ions between the positive and negative electrodes of a lithium-ion battery, ensuring the battery's advantages such as high voltage and high specific energy. The electrolyte is typically prepared under specific conditions and in specific proportions from high-purity organic solvents, lithium salts, and necessary additives.
II. Three common types of lithium battery electrolyte components
1. Ethylene carbonate: Molecular formula C3H4O3
A transparent, colorless liquid (>35℃), which becomes a crystalline solid at room temperature. Boiling point: 248℃/760mmHg, 243-244℃/740mmHg; Flash point: 160℃; Density: 1.3218; Refractive index: 1.4158 (50℃); Melting point: 35-38℃. This product is a good solvent for polyacrylonitrile and polyvinyl chloride. In the battery industry, it can be used as an excellent solvent for lithium battery electrolytes.
2. Propylene carbonate: Molecular formula C4H6O3
It is a colorless and odorless, or pale yellow, transparent liquid, soluble in water and carbon tetrachloride, and miscible with acetone, benzene, etc. It is an excellent polar solvent. This product is mainly used in polymer processing, gas separation processes, and electrochemistry. It is particularly used to absorb carbon dioxide from natural gas and ammonia synthesis feedstock in petrochemical plants. It can also be used as a plasticizer, spinning solvent, and extractant for olefins and aromatics.
3. Diethyl carbonate: Molecular formula CH3OCOOCH3
Colorless liquid with a slight odor; vapor pressure 1.33 kPa/23.8℃; flash point 25℃, melting point -43℃; boiling point 125.8℃; solubility: insoluble in water, miscible with most organic solvents such as alcohols, ketones, and esters; main uses: used as a solvent and in organic synthesis.
III. Main Components of Lithium-ion Battery Electrolyte
Lithium battery electrolytes mainly consist of three parts: solvent, lithium salt, and additives.
1. Solvent
The primary function of solvents in lithium-ion battery electrolytes is to dissolve lithium salts. The main solvents in electrolytes include cyclic carbonates (PC, EC); chain carbonates (DEC, DMC, EMC); and carboxylic acid esters (MF, MA, EA, MA, MP, etc.).
2. Lithium salts
High-quality lithium salts have a significant impact on the energy density, power density, electrochemical window, cycle life, and safety performance of lithium batteries. Commonly contained elements in lithium salts include LiPF6, LiClO4, LiBF4, and LiAsF6.
3. Additives
The main types of additives used in lithium battery electrolytes include film-forming additives, conductive additives, flame-retardant additives, overcharge protection additives, additives that control the H2O and HF content in the electrolyte, additives that improve low-temperature performance, and multifunctional additives.
IV. How to Choose Lithium-ion Battery Electrolyte?
1. It exhibits good electrochemical stability and does not react with positive electrode materials, negative electrode materials, separators, current collectors, binders, etc.
2. It has good ionic conductivity, high dielectric constant, low viscosity, and low resistance to ion migration;
3. It remains liquid over a wide temperature range, typically -40℃ to 70℃, making it suitable for improving the high and low temperature characteristics of lithium batteries;
4. It can optimally promote the reversible reaction of the electrode, that is, it has high cycle efficiency;
5. Environmentally friendly, preferably non-toxic or low-toxic.
V. Future Development Trends of Lithium-ion Battery Electrolytes
Lithium-ion battery electrolytes, leveraging their comprehensive advantages, are entering a much larger industrial cluster—the automotive power battery sector. To adapt to this vast industry, the future development trend of lithium-ion battery electrolyte components will primarily focus on novel solvents, ionic liquids, additives, and new lithium salts. These will be matched with novel positive and negative electrode materials, thereby making lithium batteries safer, with higher power and larger capacity, ultimately enabling their safe and convenient application in electric vehicles, energy storage, aerospace, and a wider range of fields.
Currently, the entry barrier for the lithium battery electrolyte market is not high, but there are hidden technological barriers. With the localization of key raw materials, the cost of electrolytes has been further reduced. Japanese and Korean companies have also begun to transfer their manufacturing plants to China. It is believed that in the near future, Chinese lithium battery electrolyte components will go global.
