Physicochemical Dual Cross‐Linking Conductive Polymeric Networks Combining High Strength and High Toughness Enable Stable Operation of Silicon Microparticle Anodes

• Published in: Advanced materials (Weinheim) 2023-07, Vol.35 (29), p.e2301320-n/a
• Main Authors: Zhang, Biao, Dong, Yanling, Han, Jingrui, Zhen, Yunjing, Hu, Chuangang, Liu, Dong
• Format: Article
• Language: English
• Subjects: Anodes; conductive polymeric networks; Dissipation; Electrode materials; Electrodes; energy‐dissipation strategies; Finite element method; High strength; high strength and high toughness; Interface stability; Lithium-ion batteries; Materials science; Microparticles; Molecular chains; Nitrile rubber; physicochemical dual cross‐linking; Polyacrylic acid; Silicon; silicon anodes; Softness; Stiffness; Tannic acid; Toughness
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202301320

The poor interfacial stability and insufficient cycling performance caused by undesirable stress hinder the commercial application of silicon microparticles (µSi) as next‐generation anode materials for high‐energy‐density lithium‐ion batteries. Herein, a conceptionally novel physicochemical dual cross‐linking conductive polymeric network is designed combining high strength and high toughness by coupling the stiffness of poly(acrylic acid) and the softness of carboxyl nitrile rubber, which includes multiple H‐bonds, by introducing highly branched tannic acid as a physical cross‐linker. Such a design enables effective stress dissipation by folded molecular chains slipping and sequential cleavage of H‐bonds, thus stabilizing the electrode interface and enhancing cycle stability. As expected, the resultant electrode (µSi/PTBR) delivers an unprecedented high capacity retention of ≈97% from 2027.9 mAh g−1 at the 19th to 1968.0 mAh g−1 at the 200th cycle at 2 A g−1. Meanwhile, this unique stress dissipation strategy is also suitable for stabilizing SiOx anodes with a much lower capacity loss of ≈0.012% per cycle over 1000 cycles at 1.5 A g−1. Atomic force microscopy analysis and finite element simulations reveal the excellent stress‐distribution ability of the physicochemical dual cross‐linking conductive polymeric network. This work provides an efficient energy‐dissipation strategy toward practical high‐capacity anodes for energy‐dense batteries. A physicochemical dual cross‐linking conductive polymeric network coupling the stiffness of poly(acrylic acid) and the softness of carboxyl nitrile rubber includes robust chemical cross‐linking and multiple physical cross‐linking. Such a design can effectively dissipate the undesirable stress of silicon microparticle anodes by folded molecular chains slipping and sequential cleavage of H‐bonds, thus stabilizing the electrode interface and enhancing cycle stability.