A New PVH Based Hyperbranched Polyzwitterion Electrolyte for Lithium‐Ion Batteries

Firstly, the third‐generation hyperbranched polymer with thiol groups at the ends was synthesized by the method of A 2 + B 3 . Then, it was reacted with 3‐{dimethyl‐[2‐(2‐methylprop‐2‐enoyloxy)ethyl]‐azaniumyl}propane‐1‐sulfonate (SBMA) to obtain a hyperbranched polymer with SBMA at the ends (HBP). Finally, different volumes of solution HBP and lithium chloride were added to poly(vinylidene fluoride‐hexafluoropropylene) (PVH) solution, and after vacuum drying, a series of solid polymer electrolytes were obtained. The structures of the hyperbranched polymers and electrolytes were characterized by 1 H nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared spectroscopy (FT‐IR). The mechanical properties of the electrolytes were tested by tensile tests. The thermal properties were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The electrochemical properties were characterized using an electrochemical workstation and Land test instrument. The results show that when the content of HBP is 30% and lithium chloride is 2.0%, the electrolytes have excellent mechanical and thermal properties. The PVH‐HBP 30 ‐LiCl 2.0 has a stable electrochemical window of 4.7 V, and its ionic conductivity is around 6.4 × 10 −4 S cm −1 at room temperature. The assembled LiFePO 4 |PVH‐HBP 30 ‐LiCl 2.0 |Li cell maintains a highly reversible capacity and excellent cycling performance after cycling at 0.5°C for 200 times.