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Micrometer-sized silicon suboxide (SiO x ) materials are accepted as high volumetric energy density anodes for upcoming lithium-ion batteries. However, the interfacial instability and severe side reaction on the gradually pulverized silicon-based particles during the alloying/dealloying process due to mechanical contact loss and sluggish charge transfer are responsible for the fast capacity decay and safety concerns. Herein, a novel multifunctional binder (CP) was constructed from ionic crosslinking between carboxymethyl chitosan and polyacrylic acid. The dynamic ionic bonding network together with reversible multiple hydrogen bonding contributes not only to the simultaneously improved tensile strength and elasticity, but also to the excellent self-healing property of CP. Additionally, the CP binder is detected for covalent bonding with microstructure SiO x particles to enhance electrode structural integrity. Moreover, the CP binder also shows high ionic conductivity at room temperature and helps to construct a highly stable lithium-ion conducting interphase. As a result, the micrometer-sized SiO x electrode with CP delivers a long-term capacity retention of 82.8% in 1,000 cycles under a high current density of 2.0 A/g, which contributes to the excellent cycling stability of SiO x @CP|NCM811 full cells. This work provides a supramolecular design strategy of developing multifunctional polymeric binders toward micro/nanostructure silicon-based anodes with highly mechano-electrochemical coupling interfacial durability in high-energy-density batteries.
Ye et al. (Tue,) studied this question.