A Formula to Customize Cathode Binder for Lithium Ion Battery

The binder plays a crucial role in binding the solid electrode components and fixing them to the current collector, ensuring good contact and transformation. The high-energy-density cathode poses several challenges for the Polyvinylidene fluoride (PVDF) binder, such as high electrode potential, mass loading, and binding force. Although various new binders are proposed to optimize the electrochemical performance of cathode, the design focus and mechanisms often lack universality. This study introduces a design strategy for the cathode binder from the perspective of molecular structure design. The performance of the binder is optimized by adjusting the soft-hard and hydrophilic-hydrophobic balances of the polymer, and the effectiveness of this strategy is verified in the LiCoO2 (LCO) system. The optimized copolymer binder improves the cycling stability of the LCO electrode under high load and low binder content conditions and even achieves stable operation at a high charging voltage of 4.6 V. The mechanism for improving the performance of LCO electrodes is that the optimized binder stabilizes the electrode structure, the active material particle structure, and the active material interface. This design strategy provides a valuable reference for customizing cathode binders.