Polymer-Shell Battery Additive for LiPF6 Heat Stability

The patent introduces a polymer-coated lithium salt additive as an intermediary substance. This additive has a polymer shell that remains stable at high temperatures while containing lithium salt in the core that can slowly release. The intermediary additive protects the main LiPF6 electrolyte from thermal decomposition by providing a stable alternative lithium source and forming protective films on electrode surfaces, thereby resolving the contradiction between electrochemical performance and thermal stability.

The patent modifies the physical and chemical parameters of the lithium salt by coating it with a polymer layer. This changes the release behavior of the lithium salt from immediate dissolution to controlled gradual release. The polymer coating acts as a barrier that controls the interaction between lithium salt and electrolyte/solvent, preventing rapid decomposition at high temperatures while still allowing electrochemical function, thus resolving the thermal stability issue.

The patent applies preliminary action by having the polymer-coated lithium salt additive pre-form protective films on the electrode surfaces before thermal runaway can occur. The additive proactively stabilizes the electrolyte system at high temperatures by releasing lithium ions that form stable SEI (solid electrolyte interface) layers, preventing the harmful decomposition reactions of LiPF6 that would otherwise lead to safety issues and resistance increase.

The patent converts the potential harm of lithium salt decomposition at high temperatures into a beneficial effect. Instead of allowing LiPF6 to decompose harmfully into PF5 and other toxic gases, the controlled-release polymer-coated lithium salt provides a benign lithium source that forms protective films. The thermal stress that would normally cause degradation is converted into a beneficial film-forming process that enhances safety and maintains performance.