The quest for higher energy density in lithium-ion batteries often leads researchers to explore higher operating voltages. However, operating at elevated voltages presents significant challenges, primarily related to the stability of the electrolyte and electrode interfaces. Electrolyte decomposition and the formation of resistive layers can severely limit battery performance and lifespan. This is where advanced electrolyte additives, such as Lithium difluoro(oxalato)borate (LiDFOB), play a critical role.

LiDFOB has garnered considerable attention for its ability to enhance the stability of lithium-ion batteries operating at high voltages. Its unique chemical structure allows it to preferentially decompose and form protective interfacial layers on both the anode and cathode. On the cathode, these layers are particularly effective at preventing oxidative decomposition of the electrolyte and mitigating the corrosive effects of species like hydrofluoric acid (HF) and oxygen radicals. This protection is vital for maintaining the structural integrity of high-voltage cathode materials, such as nickel-rich layered oxides, preventing irreversible phase transitions and capacity loss.

The mechanism behind LiDFOB's protective action involves its participation in forming a robust CEI (Cathode Electrolyte Interphase) film. Theoretical calculations and experimental data, including XPS and TOF-SIMS analyses, confirm that the decomposition products of LiDFOB incorporate boron, fluorine, and oxygen, forming a highly stable and electronically insulating film. This film effectively suppresses unwanted side reactions, thereby maintaining the cathode's electrochemical activity and extending its operational lifespan, even when charged to high cut-off voltages like 4.6 V.

Similarly, on the anode side, LiDFOB aids in the formation of a stable SEI (Solid Electrolyte Interphase) layer. This is crucial for preventing lithium dendrite formation and ensuring uniform lithium plating and stripping. A stable SEI layer, often containing boron-oxygen-carbon (B-O-C) and boron-fluorine (B-F) bonds, significantly reduces interfacial resistance and improves the coulombic efficiency of the battery.

The practical implications are substantial. Batteries incorporating LiDFOB demonstrate remarkable improvements in capacity retention and rate capability, even under demanding high-voltage cycling conditions. For industries focused on advancing energy storage, from electric vehicles to grid-scale applications, materials like LiDFOB are indispensable. By providing a stable and protective environment for battery operation, LiDFOB is instrumental in unlocking the full potential of high-voltage battery chemistries, paving the way for more powerful and durable energy storage solutions.