Gel Polymer Electrolyte Salt Composition for Low-Resistance Li-Ion Cells

The patent changes the chemical composition parameters of the electrolyte by introducing a specific mixture of lithium salts (LiPF6, LiDFOB, and LiFSI or LiTFSI) with controlled ratios. This compositional parameter change modifies the electrochemical behavior during initial charging, preventing monomer reduction while maintaining electrolyte functionality. The specific salt mixture creates a more stable interface that avoids forming the highly resistive passivation layer, thus resolving the contradiction between containment reliability and discharge capacity.

The patent creates a composite electrolyte system by combining cross-linked gel polymer matrix with a specific mixture of lithium salts and residual monomers. This composite structure allows the gel to provide containment while the controlled salt mixture prevents harmful reactions. The composite nature of the electrolyte (polymer matrix + salt mixture + controlled monomer content) enables simultaneous achievement of mechanical containment and electrochemical performance.

Instead of changing the initiator concentration parameter, the patent changes the lithium salt mixture composition parameter. This alternative parameter change achieves the same goal of reducing harmful residual monomer effects through a different mechanism (controlling SEI formation chemistry rather than polymerization kinetics). This approach maintains simpler preparation procedures while achieving the desired electrochemical performance.

The lithium salt mixture acts as an intermediary substance that mediates between the residual monomers and the electrode surface. Rather than trying to eliminate monomers completely through higher initiator concentrations, the salt mixture intermediates the interaction by controlling the reduction reactions at the electrode, preventing the formation of highly resistive passivation layers. This intermediary approach simplifies the preparation process while maintaining high discharge capacity.

The patent changes the chemical environment parameters by introducing a specific lithium salt mixture (LiPF6, LiDFOB, LiFSI/LiTFSI) that alters the electrochemical reactions during initial charging. This parameter change transforms the harmful reduction of acrylate monomers into a controlled process where the salt mixture components preferentially form a stable solid electrolyte interface, preventing the formation of highly resistive passivation layers while maintaining gel structure integrity.

The patent converts the potentially harmful presence of residual monomers into a beneficial effect. By controlling the lithium salt mixture composition, the residual monomers are directed to participate in forming a stable and conductive solid electrolyte interface rather than highly resistive passivation layers. The same residual monomers that could be harmful are thus converted into a beneficial component of the electrode interface, improving overall cell performance.