Reversible Nano Crystalline-Phase Transformation in Si-Based Anode Enables Stable All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sulfide-based all-solid-state batteries with silicon (Si) anodes offer high safety and energy density.
• Si anodes suffer from structural degradation and slow kinetics, leading to rapid capacity decay and limited battery life.
• Developing stable and high-capacity Si anodes is crucial for advancing next-generation batteries.

Purpose of the Study:

• To engineer a stable and high-capacity silicon-based anode for all-solid-state batteries.
• To mitigate structural degradation and improve reaction kinetics of Si anodes during battery cycling.
• To enhance the overall performance and cycle life of solid-state batteries.

Main Methods:

• Incorporation of phosphate (P) and zinc (Zn) into a silicon (Si) matrix to create a novel anode material.
• Electrochemical characterization of the P- and Zn-modified Si anode.
• In situ phase transformation analysis during battery cycling.
• Fabrication and testing of NCM90-based full cells utilizing the developed anode.

Main Results:

• The P- and Zn-modified Si anode undergoes reversible nanocrystalline-phase transformations (Li₁₅Si₄, LiZn, Li₃P) during cycling, effectively reducing expansion stress and maintaining structural integrity.
• Zinc and phosphate addition lowers the Li-ion diffusion energy barrier and band gap of Si, enhancing ion and electron transport.
• NCM90 full cells with the new anode achieved stable cycling for over 3,000 cycles at a 2C rate.

Conclusions:

• The reversible nanocrystalline-phase transformation strategy effectively addresses the structural instability and kinetic limitations of Si anodes.
• The alloy-based anode design significantly improves the cycle life and stability of sulfide-based all-solid-state batteries.
• This approach provides a promising pathway for developing high-performance, long-lasting all-solid-state batteries.