Porous Organic Cage‑Based Quasi‑Solid‑State Electrolyte with Cavity‑Induced Anion‑Trapping Effect for Long‑Life Lithium Metal Batteries

Porous organic cages(POCs)with permanent porosity and excellent host–guest property hold great potentials in regulating ion transport behavior,yet their feasibility as solid-state electrolytes has never been testified in a practical battery.Herein,we design and fabricate a quasi-solid-state electrolyte(QSSE)based on a POC to enable the stable operation of Li-metal batteries(LMBs).Benefiting from the ordered channels and cavity-induced anion-trapping effect of POC,the resulting POC-based QSSE exhibits a high Li+transference number of 0.67 and a high ionic conductivity of 1.25×10^(−4) S cm^(−1) with a low activation energy of 0.17 eV.These allow for homogeneous Li deposition and highly reversible Li plating/stripping for over 2000 h.As a proof of concept,the LMB assembled with POC-based QSSE demonstrates extremely stable cycling performance with 85%capacity retention after 1000 cycles.Therefore,our work demonstrates the practical applicability of POC as SSEs for LMBs and could be extended to other energy-storage systems,such as Na and K batteries.

Revealing the key role of non-solvating diluents for fast-charging and low temperature Li-ion batteries

Fast-charging and low temperature operation are of vital importance for the further development of lithium-ion batteries(LIBs),which is hindered by the utilization of conventional carbonate-based electrolytes due to their slow kinetics,narrow operating temperature and voltage range.Herein,an acetonitrile(AN)-based localized high-concentration electrolyte(LHCE)is proposed to retain liquid state and high ionic conductivity at ultra-low temperatures while possessing high oxidation stability.We originally reveal the excellent thermal shielding effect of non-solvating diluent to prevent the aggregation of Li^(+) solvates as temperature drops,maintaining the merits of fast Li transport and facile desolvation as at room temperature,which bestows the graphite electrode with remarkable low temperature performance(264 mA h g^(-1) at-20 C).Remarkably,an extremely high capacity retention of 97%is achieved for high-voltage high-energy graphite||NCM batteries after 250 cycles at-20 C,and a high capacity of 110 mA h g^(-1)(71%of its room-temperature capacity)is retained at-30°C.The study unveils the key role of the non-solvating diluents and provides instructive guidance in designing electrolytes towards fast-charging and low temperature LIBs.

Synergistic Effect of High Donor Electrolyte and Catalytic Separator for Practical Lithium–Sulfur Batteries

The commercialization of lithium-sulfur(Li-S)batteries has been hampered by the low utilization of S,resulting in low practical energy density and the severe shuttle effect of lithium polysulfides(LiPSs)that leads to poor cycle life.Herein,a combined strategy of electrolyte engineering and separator functionalization was proposed to solve the conflict between high S utilization and cycling life.We have demonstrated that the high donor electrolyte regulates the solvation of LiPSs with the formation of S_(3)^(·-)to induce radical-assisted efficient conversion pathway and threedimensional(3D)Li2S deposition,which greatly enhanced the S utilization while exacerbating the shuttling of LiPSs.Fortunately,the carbon nanosheet-based modified separator with abundant Zn-Co diatomic metal sites efficiently inhibited the shuttling of LiPSs by catalyzing the conversion reaction of LiPSs.Hence,the resulting Li-S battery delivered a remarkably high capacity of 1300 mAh g^(-1) with a high average coulombic efficiency of 99.4% during cycling.Even at a high S mass loading(9.3 mg cm^(-2))and lean electrolyte condition(E/S=3μL mg^(-1)),the Li-S battery still delivered a high capacity of 1088 mAh g^(-1),representing a significant advancement in designing practically high energy Li-S batteries with long cycle life.