High-Energy and Long-Lasting Lithium Metal Batteries Lithium Employing Garnet Solid Electrolytes and Interlayers

Lithium metal batteries (LMBs) are considered the most promising next-generation battery system because of their high energy density and safety. Significant research effort has been devoted to developing more stable and energy-dense LMBs than the state-of-the-art Li-ion batteries. However, the LMB performance remains unsatisfactory for commercialization, primarily owing to the inability of solid electrolytes to block Li dendrite propagation.<br/>Herein, we report that the compatibility between LLZO and lithium metal is crucial for the long-term stability, which can be accomplished by regulating bulk dopants and the corresponding dopant-specific interfacial treatment using protonation/etching. It is demonstrated that LMB using tailored garnet-type Li_7-xLa_3-aZr_2-bO₁₂ (LLZO) solid electrolytes shows remarkable stability and energy density, meeting the lifespan requirements of commercial applications (cumulative capacity : &gt; 4000 mAh cm⁻² at 3mA cm⁻²).<br/>We further demonstrate highly stable LMB even at room-temperature (25^oC) employing garnet-type oxide electrolyte by introducing a carbon-based interlayer with careful interface engineering. It is theoretically and experimentally demonstrated that our design effectively regulated Li deposition away from the solid electrolyte, preventing dendrite penetration. Overall, our garnet-type oxide-based LMB exhibited a high energy density of ~680 Wh/L for over 800 cycles at 25^oC without using external pressure, which could meet the cycling requirements and the operating conditions of smartphone batteries, which are represented by: (i) 400 cycles @88% cycle retention without Li metal shorting at the operating current density of 1.6 mA/cm²(0.5 C-rate charging/discharging) and (ii) room-temperature operation under the condition of no external pressure. Moreover, we successfully developed a tape-cast solid electrolyte with a large area (1 inch × 1 inch) and demonstrated excellent cycling performance at 25 °C in a 10-mAh-capacity cell beyond a coin-size cell (~1 mAh).