Silicon anode for all-solid-state lithium secondary batteries and all-solid-state lithium secondary batteries comprising the same

Air-stable silicon anode with sequentially stacked pre-lithiation and lithium-alloy protective layers

This technology forms a pre-lithiation layer on a silicon anode, followed by a lithium-alloy metal protective layer. This structure maintains the lithium-silicon alloy integrity and controls interfacial resistance even when exposed to the atmosphere.

Pre-lithiation of silicon anodes has historically led to instability and performance degradation when exposed to air. Furthermore, these anodes required high operating pressures and suffered from low discharge capacity and poor rate capability due to interfacial side reactions between the silicon anode and the solid electrolyte.

This technology involves coating lithium onto the anode active material layer to create a pre-lithiation layer, then applying a protective layer of lithium-alloying metals such as tin (Sn) or silver (Ag). The formation of a Li-Si alloy internally and a Li-M alloy in the protective layer ensures structural stability in ambient air and enables high discharge capacity under low-pressure conditions. Applicable to all-solid-state EV batteries, portable electronics, and power device cells, this technology reduces reliance on dry rooms and improves handling during cell assembly.

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Key Features:

• Anode active material layer formed on an anode current collector, comprising silicon, a conductive agent, and a binder
• Pre-lithiation layer formed by coating lithium onto the anode active material layer, creating a lithium-silicon alloy in the interfacial region
• Lithium-alloying metal protective layer formed by coating lithium-alloying metals such as Sn, Ag, or Zn onto the pre-lithiation layer to create a lithium-metal alloy
• Step of coating lithium onto the anode active material layer using thermal evaporation, physical vapor deposition, or sputtering with lithium metal

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This invention was developed with support from the Ministry of Science and ICT under the project for developing bridge technologies for large-area, 600Wh/L-class all-solid-state EV batteries.

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