Structure Tailoring Enabled Self‐Catalyzed Imidization for Engineering a Highly Adhesive and Ion‐Conductive Polyimide Network Toward Ultra‐Stable Silicon Anodes

Abstract

ABSTRACT Silicon (Si) is widely recognized as one of the most promising anode materials for next‐generation lithium‐ion batteries (LIBs). Nevertheless, its practical application is hindered by significant volume expansion and poor interfacial stability. Herein, a highly adhesive and ion‐conductive polyimide binder, denoted as PIy, is synthesized via low‐temperature self‐catalyzed imidization through the copolymerization of 3,3’,4,4’‐biphenyltetracarboxylic dianhydride (BPDA) with 2,2’‐bis[4‐(4‐aminophenoxy)phenyl]propane (BAPP) as the tough monomer, 4,4’‐diamino‐2,2’‐bipyridyl (DAPY) as a base‐catalyzing component, and 2‐(5‐amino‐2‐methylanilino)‐4‐(3‐pyridyl)pyrimidine (AMPY) as an end‐capping agent. DAPY and AMPY effectively lower the activation energy of poly(amic acid) imidization which enables cyclization to proceed at low temperatures and the pyridine groups promote Li + transport. BPDA and BAPP contain abundant aromatic rings that provide high toughness and impart a high modulus to suppress volume changes. Meanwhile, the flexible ‐O‐ segments enhance chain mobility adapting to expansion while maintaining structural integrity. The Si@PIy‐185 °C electrode exhibits excellent long‐term cycling stability, maintaining a high specific capacity of 1118.6 mAh g − 1 at 1 A g − 1 even after 1000 cycles.The full cell of the SiO x @PIy‐185 °C//NCM811 exhibits a remarkable capacity retention of 87.8% after 100 cycles, highlighting the potential of the low‐temperature imidized PI binder for high‐energy‐density LIBs.