Diffusion-Controlled Porous Crystalline Silicon Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Nanostructured porous silicon shows promise as a host for lithium-metal plating in batteries.
• Existing challenges include silicon self-pulverization, lithium dendrite formation, and difficulties in wafer-level integration of pure silicon anodes.

Purpose of the Study:

• To develop wafer-scale porous crystalline silicon (PCS) anodes with enhanced stability and performance for lithium-metal batteries.
• To address limitations of silicon self-pulverization and lithium dendrite growth through surface modification and controlled anodization.

Main Methods:

• Fabrication of low-resistance, wafer-scale porous crystalline silicon (PCS) anodes using combined wafer surface cleaning (SC) and anodization.
• Embedding a nanoporous layer for lithium-ion plating and diffusion regulation.
• Characterization of lithiophilic surface formation and correlation with surface groups and X-ray structure.
• Electrochemical testing of full cells with different cathode materials (NMC811, LCO) and anodization times.

Main Results:

• Achieved high performance in full cells: NMC811 | 4800s SC-PCS demonstrated 195 mAh/g (99.9% C.E.) at C/3 for 50 cycles, and 165 mAh/g, 587 Wh/kg (97.1% C.E.) over 350 cycles.
• Demonstrated low resistivity (24 Ω*cm²) for SC-PCS anodes over 900 cycles.
• LCO | 500s SC-PCS cells showed 102 mAh/g (94.1% C.E.) at 1C for 350 cycles.
• Pre-lithiation enabled sustainable lithium-metal plating/stripping on the lithiophilic surface and within the SC-PCS nanostructure.

Conclusions:

• Low-cost SC-PCS anodes, requiring no composite formulation, offer a viable solution for stable lithium-metal battery anodes.
• The developed method facilitates wafer-level integration and overcomes critical limitations of pure silicon anodes.
• Anodization time and C-rate are key factors determining competitive full cell performance.