Ultra-High Capacity Density Lithium Metal Battery is Effectuated via Coupling Single Lithium-Ion Conductor and...

Among various strategies to solve the issue of lithium dendrites in high voltage lithium metal batteries (HV-LMBs), lithium-ion sieves (LISs) and single lithium-ion conductors (SLICs) are considered the most effective and fundamental approaches. However, the performance improvement of HV-LMBs achieved through a single strategy remains significantly below the expected level. We aimed to couple a LIS with an SLIC to synergistically enhance the performance of HV-LMBs and successfully synthesized the rare earth MOF-based SLIC [LiY(BDC)₂(H₂O)]·2H₂O (LiYBDC-H₂O, H₂BDC = 1,4-dicarboxybenzene) via in-situ synthesis. Its conductivity is significantly enhanced following solvation and gelation (0.972/0.228 mS cm^-1 vs. 0.036 mS cm^-1). More importantly, NMR/IR characterization and theoretical calculation demonstrate that LiYBDC preferentially coordinates with EC (EC = ethylene carbonate) in gelated quasi-SLIC LFE@LiYBDC. This interaction facilitates the formation of LIS resulting in an exceptionally high lithium-ion transfer number of 0.92. Last but not the least, the synergetic strategy combining the LIS and SLIC not only greatly improved the LiNi_1/3Co_1/3Mn_1/3O₂|Li with the second highest capacity density (167.82 mAh g^-1) but also markedly enhanced Li|Li and Cu|Li batteries with the longest Li|Li and Cu|Li cycle stability of 3000 h and 700 h.