Single-Ion Conducting Soft Electrolytes for Semi-Solid Lithium Metal Batteries Enabling Cell Fabrication and Operation under Ambient Conditions

Despite their potential as post lithium-ion batteries, solid-state Li-metal batteries are struggling with insufficient electrochemical sustainability and ambient operation limitations. These challenges mainly stem from lack of reliable solid-state electrolytes. Here, a new class of single-ion conducting quasi-solid-state soft electrolyte (SICSE) for practical semi-solid Li-metal batteries (SSLMBs) is demonstrated. The SICSE consists of an ion-rectifying compliant skeleton and a nonflammable coordinated electrolyte. Rheology-tuned SICSE pastes, in combination with UV curing-assisted multistage printing, allow fabrication of seamlessly integrated SSLMBs (composed of a Li metal anode and LiNi_0.8Co_0.1Mn_0.1 cathode) without undergoing high-pressure/high-temperature manufacturing steps. The single-ion conducting capability of the SICSE plays a viable role in stabilizing the interfaces with the electrodes. The resulting SSLMB full cell exhibits stable cycling performance and bipolar configurations with tunable voltages and high gravimetric/volumetric energy densities (476 Wh kg_cell⁻¹/1102 Wh L_cell⁻¹ at four-stacked cells with 16.656 V) under ambient operating conditions, along with low-temperature performance, mechanical foldability, and nonflammability.