Lithiation-induced conductivity modulation in Prussian blue interlayer for stable Li/garnet solid-state batteries

The garnet-based solid-state batteries have the potential advantages of high energy density and safety. However, the poor solid-solid contact and Li dendrite growth at the anode interface lead to uneven Li deposition or short circuit, which hinders their practical application. Here, we propose a Prussian blue (PB) interlayer to improve the interface contact and charge transfer between Li anode and garnet electrolyte by lithiation-induced conductivity modulation. This mixed-conducting interlayer with unique 3D open framework enables a well welded interface with enhanced lithiophilicity and uniform Li diffusion. The Li/garnet interface resistance is significantly reduced. This lithiated PB interlayer is highly durable with invariable thickness during cycling, leading to a highly stable cycling of Li plating/stripping and corresponding LiFePO4 full cells without dendrite growth. The dual modulation of ion and electron transports in an integrated structure without phase segregation through thermal or electrochemical lithiation provides a solution to the challenge of solid-solid interfaces and the development of practical solid-state batteries.

Automated summary

Garnet-based solid-state batteries have high energy density and safety potential. However, poor interface contact and Li dendrite growth hinder their practical application. A Prussian blue (PB) interlayer is proposed to improve the interface and charge transfer through conductivity modulation. This lithiated PB interlayer with a unique 3D open framework enhances lithiophilicity and uniform Li diffusion. It reduces the resistance at the Li/garnet interface and enables stable cycling without dendrite growth.