0428同步年報-2021-全

Energy Science 063 A ll-solid-state lithium batteries (ASSLB) are regarded as one of the next- generation energy storage technologies to compete or even to surpass the state-of- the-art liquid-based lithium-ion batteries. By replacing organic liquid electrolytes with non- flammable solid electrolytes (SE), ASSLB are expected to address safety concerns associated with flammable organic electrolytes, and to achieve applications over a wide temperature range. Among SE of various types, sulfide is viewed as one of the most promising SE candidates for the commercialization of high-performance ASSLB, but the narrow electrochemical stability window of sulfide SE challenges the interface stability especially at the high-voltage cathode side, thus producing much increased interfacial resistance, poor rate performance and rapid capacity fading. Moreover, the structural mismatch and electrochemical potential discrepancy between oxide cathodes and sulfide SE render high interfacial impedances for Li-ion transport. These phenomena limit the realization of sulfide SE in high-voltage battery systems for increased energy densities. Guanglei Cui (Chinese Academy of Sciences, China) and his coworkers recently found that Li x Zr 2 (PO 4 ) 3 (LZPO) served as a proof of concept for a bidirectionally compatible buffering- layer design scheme ( Fig. 1 ) to overcome the interfacial challenges of sulfide-based high-voltage ASSLB (HVASSLB). Employing X-ray absorption spectra (XAS) at TLS 16A1 , 1 the mechanism of improvement of the LZPO buffering layer on interfacial stability and Li-ion transport dynamics was studied. As shown in Fig. 2 , the S K-edge and P K-edge on the composite cathode side were characterized using the fluorescence-yield mode to investigate the interface stability between Li 6 PS 5 Cl (LPSCl) and LiCoO 2 (LCO) with and without the LZPO buffering layer. An effective chemical stability between LZPO-LCO and LPSCl was observed. In contrast, LPSCl is thermodynamically unstable with LCO but undergoes spontaneous decomposition in contact with LCO. It was concluded that the LZPO buffering layer can remarkably enhance the stability of the LCO/LPSCl interface and the Li-ion transport dynamics even cycled at voltage 4.5 V, which Fig. 1 : Schematic illustration of the design of a bidirectionally compatible buffering layer. [Reproduced from Ref. 1] Fig. 2 : XAS at S K-edge and P K-edge for pristine LPSCl (P-LPSCl), pristine LCO/LPSCl composite cathode (P-LCO/LPSCl), pristine LZPO- LCO/LPSCl composite cathode (P-LZPO-LCO/LPSCl), LCO/LPSCl composite cathode after 100 cycles (C-LCO/LPSCl), and LZPO- LCO/LPSCl composite cathode after 100 cycles (C-LZPO-LCO/ LPSCl). [Reproduced from Ref. 1] Eliminating the Detrimental Effects in Solid-State Batteries A bidirectionally compatible buffering-layer enables a highly stable and conductive interface for sulfide-based all-solid- state lithium batteries.