Lithium-Ion Battery Electrolyte Additives for High-Temperature Stability

The patent uses a composite electrolyte additive system comprising a cyclic N-containing sulfonyl compound (Formula I) combined with specific ratios of VC (0.1-5 wt%), FEC (1-20 wt%), and LiDFOB (0.1-5 wt%). This composite approach creates a balanced protective film that provides high-temperature storage protection without excessive viscosity or impedance, as the different components work synergistically to form an optimized SEI film structure.

The patent optimizes the concentration parameters of each additive component to resolve the contradiction. By controlling the cyclic N-containing sulfonyl compound at 0.1-10 wt%, VC at 0.1-5 wt%, FEC at 1-20 wt%, and LiDFOB at 0.1-5 wt%, the formulation achieves the right balance between protective film quality and electrolyte fluidity, preventing both high impedance and excessive viscosity.

The electrolyte additives perform preliminary protective action by forming stable SEI films on the electrode surfaces before high-temperature storage or cycling begins. The cyclic N-containing sulfonyl compound and accompanying additives pre-condition the electrode interfaces, creating protective layers that prevent subsequent degradation during high-voltage operation and high-temperature storage, thus maintaining reliability despite increased energy density.

The electrolyte additives act as sacrificial components that form protective films through controlled decomposition. The cyclic N-containing sulfonyl compound and other additives undergo preliminary reactions to create stable SEI structures, sacrificing themselves in the process. This disposable approach allows the main electrolyte system to operate reliably under high-voltage, high-energy-density conditions without the additives needing to remain intact.