The efficiency and longevity of lithium-ion batteries are heavily influenced by the interfaces between the electrodes and the electrolyte. These interfaces, particularly the Solid Electrolyte Interphase (SEI) on the anode and the Cathode Electrolyte Interphase (CEI) on the cathode, are critical for preventing detrimental side reactions and ensuring smooth ion transport. Lithium difluoro(oxalato)borate (LiDFOB) is a key electrolyte additive that significantly contributes to the formation of stable and functional SEI and CEI layers, thereby enhancing battery performance.

The scientific understanding of LiDFOB's role is rooted in its electrochemical behavior and decomposition pathways. Through theoretical calculations, such as Density Functional Theory (DFT), and experimental techniques like XPS and TOF-SIMS, researchers have elucidated how LiDFOB interacts with electrode materials and electrolyte components.

At the anode, LiDFOB undergoes preferential reduction. This process, often synergistic with the reduction of common electrolyte solvents like ethylene carbonate (EC), leads to the formation of a complex SEI layer. This layer is characterized by the presence of boron-oxygen-carbon (B-O-C) and boron-fluorine (B-F) bonds. These components contribute to the SEI's electronic insulating properties, which is crucial for preventing further electrolyte decomposition, while maintaining good ionic conductivity for lithium ions. The stability of this LiDFOB-derived SEI layer significantly improves the Coulombic efficiency of lithium plating and stripping and suppresses the formation of lithium dendrites, a major safety concern.

On the cathode side, LiDFOB is preferentially oxidized, especially at higher potentials. This oxidative decomposition leads to the formation of a CEI layer composed of species such as BF3, BF2OH, and BF2OBF2. This CEI layer is critical for high-voltage lithium-ion batteries as it acts as a barrier against aggressive electrolyte decomposition and scavenges harmful species like HF and reactive oxygen species. Furthermore, the boron within the CEI can form strong coordination bonds with the lattice oxygen of the cathode material. This interaction helps to stabilize the cathode's structure, mitigating irreversible lattice changes and oxygen loss, which are common causes of capacity fade in nickel-rich cathodes.

The effectiveness of LiDFOB lies in its ability to form these robust interfaces that enhance ionic conductivity and electronic insulation, while preventing unwanted chemical reactions. The synergy between LiDFOB and other electrolyte components, such as EC, plays a vital role in tailoring the properties of the SEI and CEI layers. This detailed understanding of the formation mechanisms allows for the optimization of electrolyte formulations to achieve superior battery performance, longer cycle life, and improved safety. For companies like NINGBO INNO PHARMCHEM CO.,LTD., a deep understanding of these chemical mechanisms is essential for producing high-quality LiDFOB that meets the demanding requirements of advanced battery technologies.