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 LiNi0.5 Co0.3 Mn0.2 O2 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.

Flexible Interface Design for Stress Regulation of a Silicon Anode toward Highly Stable Dual-Ion Batteries.

Dual-ion batteries (DIBs) have attracted increasing attention due to their high working voltage, low cost, and environmental friendliness, yet their development is hindered by their limited energy density. Pairing silicon-a most promising anode due to its highest theoretical capacity (4200 mAh g-1 )-with a graphite cathode is a feasible strategy to address the challenge. Nevertheless, the cycling stability of silicon is unsatisfactory due to the loss of electrical contact resulting from the high interface stress when using rigid current collectors. In this work, a flexible interface design to regulate the stress distribution is proposed, via the construction of a silicon anode on a soft nylon fabric modified with a conductive Cu-Ni transition layer, which endows the silicon electrode with remarkable flexibility and stability over 50 000 bends. Assembly of the flexible silicon anode with an expanded graphite cathode yields a silicon-graphite DIB (SGDIB), which possesses record-breaking rate performance (up to 150 C) and cycling stability over 2000 cycles at 10 C with a capacity retention of 97%. Moreover, the SGDIB shows a high capacity retention of ≈84% after 1500 bends and a low self-discharging voltage loss of 0.0015% per bend after 10 000 bends, suggesting high potential for high-performance flexible energy-storage applications.