Constructing a Reinforced and Gradient Solid Electrolyte Interphase on Si Nanoparticles by In-Situ Thiol-Ene Click Reaction for Long Cycling Lithium-Ion Batteries.

Constructing a stable solid electrolyte interphase (SEI) on high-specific-capacity silicon (Si) anode is one of the most effective methods to reduce the crack of SEI and improve the cycling performance of Si anode. Herein, the authors construct a reinforced and gradient SEI on Si nanoparticles by an in-situ thiol-ene click reaction. Mercaptopropyl trimethoxysilane (MPTMS) with thiol functional groups (SH) is first grafted on the Si nanoparticles through condensation reaction, which then in-situ covalently bonds with vinylene carbonate (VC) to form a reinforced and uniform SEI on Si nanoparticles. The modified SEI with sufficient elastic Li _x SiO _y can homogenize the stress and strain during the lithiation of Si nanoparticles to reduce their expansion and prevent the SEI from cracking. The Si nanoparticles-graphite blending anode with the reinforced SEI exhibits excellent performance with an initial coulombic efficiency of ≈90%, a capacity of 1053.3 mA h g ^-1 after 500 cycles and a high capacity of 852.8 mA h g ^-1 even at a high current density of 3 A g ^-1 . Moreover, the obtained anode shows superior cycling stability under both high loadings and lean electrolyte. The in-situ thiol-ene click reaction is a practical method to construct reinforced SEI on Si nanoparticles for next-generation high-energy-density lithium-ion batteries.
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