Tape-cast Ce-substituted Li 7 La 3 Zr 2 O 12 electrolyte for improving electrochemical performance of solid-state lithium batteries

Solid-state lithium-metal batteries (SSLMBs) with a composite solid electrolyte (CSE) have great potential for achieving both high energy density and high safety and are thus promising next-generation energy storage devices. The current bottlenecks are a high electrode/electrolyte interface resistance and the limited Li + conductivity of the solid electrolyte layer. To reduce the interface resistance, a tape casting method is used to directly deposit a CSE layer (∼20 μm) onto a model LiFePO 4 cathode. The CSE slurry infiltrates the cathode layer, forming a Li + conduction network and ensuring intimate contact between the CSE and the cathode. The tape casting parameters, such as the polymer/Li salt ratio, inorganic filler fraction, and casting thickness, for the CSE layer are investigated. To increase Li + conductivity, Ce substitution is conducted for Li 7 La 3 Zr 2− x Ce x O 12 , x = 0–0.15. The effects of Ce content on the specific capacity, rate capability, and cycling stability of Li//CSE//LiFePO 4 cells are systematically studied. Li 7 La 3 Zr 1.9 Ce 0.1 O 12 ( i.e. , x = 0.1) is found to be the optimal composition; it outperforms Li 7 La 3 Zr 2 O 12 and Li 6.25 Ga 0.25 La 3 Zr 2 O 12 in terms of CSE conductivity and SSLMB charge–discharge performance.