Interface Engineering of Sulfide-Based All-Solid-State Lithium Batteries

Abstract

All-solid-state lithium batteries (ASSLBs) have gained intensive attention worldwide because of their intrinsic safety and potential high energy density.1 As a critical component in ASSLBs, various solid-state electrolytes have been extensively studied over the past decade. So far, the ionic conductivity of solid-state electrolytes, particularly sulfide electrolytes (SEs, i.e. Li10GeP2S12) is close to that of conventional liquid electrolytes. However, the electrochemical performance of SE-based ASSLBs is hindered by the large interfacial resistance between electrodes and sulfide electrolytes. The underlying reasons are detrimental interfacial reactions and insufficient solid-solid contact between electrodes and SEs in ASSLBs.2 In our research, taking the advantages of atomic/molecular layer deposition techniques, an interfacial layer with designed functionalities can be conformably interposed between the electrodes and solid-state sulfide electrolytes, aiming at overcoming the interfacial resistance. At the anode interface, a artifical solid electrolyte interphase (SEI) has been engineered to suppress the interfacial rections and lithium dendrite growth, sucessfully enabling the use of Li metal in SE-based ASSLBs.3 At the cathode interface, a dual-shell interfacial nanostructure was rationally designed, in which the inner shell LiNbO3 suppressing the interfacial reactions, while the outer shell Li10GeP2S12 providing an intimate electrode-electrolyte contact.4 As a result, the dual-shell strucutured LGPS@LNO@LCO cathode exhibits a high initial specific capacity of 125.8 mAh.g-1 (1.35 mAh.cm-2) with an initial Coulombic efficiency of 90.4% at 0.1 C and 87.7 mAh.g-1 even at 1C. Furthermore, a plastic crystal electrolyte has been developed, which can simultaneously suppress the interfacial reactions and lithium dendrite growth in ASSLBs.5 The above work not only demonstrates various strategies to enable high-energy-density ASSLBs but also provides new insights into the interfacial challenges of ASSLBs.