Significant Strain Dissipation via Stiff-Tough Solid Electrolyte Interphase Design for Highly Stable Alloying Anodes

The pulverization of alloying anodes significantly restricts their use in lithium-ion batteries (LIBs). This study presents a dual-phase solid electrolyte interphase (SEI) design that incorporates finely dispersed Al nanoparticles within the LiPON matrix. This distinctive dual-phase structure imparts high stiffness and toughness to the integrated SEI film. In comparison to single-phase LiPON film, the optimized Al/LiPON dual-phase SEI film demonstrates a remarkable increase in fracture toughness by 317.8 %, while maintaining stiffness, achieved through the substantial dissipation of strain energy. Application of the dual-phase SEI film on an Al anode leads to a 450 % enhancement in cycling stability for lithium storage in dual-ion batteries. A similar enhancement in cycling stability for silicon anodes, which face severe volume expansion issues, is also observed, demonstrating the broad applicability of the dual-phase SEI design. Specifically, homogeneous Li-Al alloying has been observed in conventional LIBs, even when paired with a high mass loading LiNi0.5Co0.3Mn0.2O2 cathode (7 mg cm-2). The dual-phase SEI film design can also accelerate the diffusion kinetics of Li-ions through interface electronic structure regulation. This dual-phase design can integrate stiffness and toughness into a single SEI film, providing a pathway to enhance both the structural stability and rate capability of alloying anodes. A dual-phase solid electrolyte interphase (SEI) design that imparts high stiffness and toughness to a single SEI film was achieved for the first time, providing a novel avenue to amplify both the structural robustness and rate capacity of alloying anodes for lithium-ion storage.+image

Automated summary

This study presents a dual-phase solid electrolyte interphase (SEI) design that incorporates Al nanoparticles within the LiPON matrix. The dual-phase structure increases the toughness and stiffness of the SEI film, leading to enhanced cycling stability for both Al and silicon anodes in lithium-ion batteries.