In Situ and Low-Cost Improvement of the Lithium Anode Interface in Garnet-Type Solid-State Electrolytes

In recent years, the development of electric vehicles and environmental concerns have made necessary improvements in the energy density and safety of lithium-ion batteries. Therefore, the development of all-solid-state lithium-ion batteries (ASSLIBs) has become imperative. One advantage of ASSLIBs is their potential for downsizing with the use of lithium metal as the anode. However, in this study, a garnet-type solid electrolyte (Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 ) was used, which has low reactivity with lithium metal. Thus, interface modification using CaCl 2 was employed to form a Li–Ca–Cl composite anode. The interfacial resistance was remarkably reduced to 7 Ω cm 2, and the symmetric cell exhibited stable cycling for 1200 h at room temperature and a current density of 0.1 mA cm –2 . The voltage ranged from ±15 to ±16 mV. The full cell demonstrated a high initial discharge capacity of 149.2 mA h g –1 and a Coulombic efficiency of 98.0% while maintaining a discharge capacity retention of 91.3% after 100 cycles. These findings lay a solid foundation for future commercial applications as interface modification was achieved through a simple spin-coating process using low-cost CaCl 2 (0.7 USD g –1 ).