Water-Based Fabrication of a Li|Li7La3Zr2O12|LiFePO4 Solid-State Battery─Toward Green Battery Production

Solid-state lithium batteries (SSLBs) are considered to be one of the most promising next-generation Li batteries due to their high capacity and intrinsic safety. However, their sustainable processing is often poorly investigated but could offer additional advantages over conventional batteries in terms of ecological and economic benefits. In this work, a sustainable, water-based processing route for garnet-supported SSLBs featuring a LiFePO 4 (LFP)-poly(ethylene oxide) (PEO) composite cathode is presented. Both the LFP-PEO cathode and the thin free-standing garnet separator (105 μm) are fabricated by water-based tape-casting. After optimizing the composition of the cathode, the full cell with a thin cathode (∼45 μm) delivers a high capacity of 136 mAh g –1 with a high Coulombic efficiency over 99% and good cycling stability for 50 cycles. However, the performance and cycling stability decrease when thicker cathodes (∼110 μm) and higher rates were applied, indicating the need for further optimization. Nevertheless, the here-presented water-based fabrication route provides a baseline for further improvements and pushes SSLB fabrication further toward a green battery production.