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<p>Silicon anodes have an ultrahigh theoretical capacity (4200 mAh g<sup>−1</sup>) but face critical issues: over 300% volumetric expansion during charge-discharge cycles and unstable rigid solid electrolyte interphase (SEI) that fractures and regenerates, accelerating capacity fading and shortening cycle life. To address these, we design a hierarchical composite <i>p</i>-<i>c</i>Si@<i>a</i>Si@MgSiN<sub>2</sub>@C, which tackles intertwined failure modes via synergistic interface engineering. It features a porous crystalline-amorphous silicon (<i>p</i>-<i>c</i>Si@<i>a</i>Si) core. The three-dimensional (3D) interconnected pores accommodate expansion, while amorphous silicon enables isotropic lithiation-induced strain. The composite also includes an <i>in-situ</i> MgSiN<sub>2</sub> transition layer that transforms into a tough Li<sub>3</sub>N-rich SEI with ultra-fast ion channels, and an outer nitrogen-doped carbon shell that provides mechanical confinement and electronic permeability. Unlike traditional rigid SEI, the MgSiN<sub>2</sub>-derived Li<sub>3</sub>N/Li-Mg mixed SEI ensures high interfacial conductivity and mitigates expansion. This design eliminates crystalline silicon lithiation phase transition barriers, achieving an initial coulombic efficiency (ICE) of 81.4%, a 64% reduction in charge transfer resistance (<i>R</i><sub>ct</sub>=16.4 Ω after 200 cycles), and fast Li<sup>+</sup> diffusion (<i>D</i><sub>Li</sub><sup>+</sup>=1.72×10<sup>−11</sup> cm<sup>2</sup> s<sup>−1</sup>). The composite anode exhibits excellent electrochemical performance, delivering 1719.3 mAh g<sup>−1</sup> at 0.2 C after 200 cycles and 823.8 mAh g<sup>−1</sup> at 0.5 C after 500 cycles. Our work resolves the ICE-cycle life trade-off of silicon anodes and provides a scalable molten salt electrolysis approach for next-generation high-energy batteries.</p>

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Toward efficient and stable lithium storage: molten salt electrolysis-constructed amorphous Si-dominant anodes with synergistic interfaces

  • 期刊论文

  • 发表日期：

    2026年5月6日

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  • Xintao Wu,
  • Haoxiang Wu,
  • Siwei Jiang,
  • Yazecheng Liu,
  • Peng Hu,
  • Tao Zhang,
  • Liuli Yao,
  • Peng Dong,
  • Wei Xiao,
  • Yingjie Zhang,
  • Zhongren Zhou

摘要

Silicon anodes have an ultrahigh theoretical capacity (4200 mAh g−1) but face critical issues: over 300% volumetric expansion during charge-discharge cycles and unstable rigid solid electrolyte interphase (SEI) that fractures and regenerates, accelerating capacity fading and shortening cycle life. To address these, we design a hierarchical composite p-cSi@aSi@MgSiN2@C, which tackles intertwined failure modes via synergistic interface engineering. It features a porous crystalline-amorphous silicon (p-cSi@aSi) core. The three-dimensional (3D) interconnected pores accommodate expansion, while amorphous silicon enables isotropic lithiation-induced strain. The composite also includes an in-situ MgSiN2 transition layer that transforms into a tough Li3N-rich SEI with ultra-fast ion channels, and an outer nitrogen-doped carbon shell that provides mechanical confinement and electronic permeability. Unlike traditional rigid SEI, the MgSiN2-derived Li3N/Li-Mg mixed SEI ensures high interfacial conductivity and mitigates expansion. This design eliminates crystalline silicon lithiation phase transition barriers, achieving an initial coulombic efficiency (ICE) of 81.4%, a 64% reduction in charge transfer resistance (Rct=16.4 Ω after 200 cycles), and fast Li+ diffusion (DLi+=1.72×10−11 cm2 s−1). The composite anode exhibits excellent electrochemical performance, delivering 1719.3 mAh g−1 at 0.2 C after 200 cycles and 823.8 mAh g−1 at 0.5 C after 500 cycles. Our work resolves the ICE-cycle life trade-off of silicon anodes and provides a scalable molten salt electrolysis approach for next-generation high-energy batteries.