Valence state of transition metal center as an activity descriptor for CO_(2) reduction on single atom catalysts

Carbon dioxide(CO_(2))catalytic reduction has been passionately pursued for a long period of time due to its special importance in alleviating the greenhouse effect as well as generating valuable fuels and chemicals[1].Among the various approaches for achieving CO_(2)conversion,considerable efforts have been devoted to electrochemical reduction of CO_(2)since this technology operates at ambient and mild environments and can potentially produce various useful products[2].

Promoting operating voltage to 2.3 V by a superconcentrated aqueous electrolyte in carbon-based supercapacitor

Aqueous supercapacitors(SCs)have attracted more and more attention for their safety,fast charge/discharge capability and ultra-long life.However,the application of aqueous SCs is limited by the low working voltage due to the narrow electrochemical stability window(ESW)of wate r.Herein,we report a new"water in salt"(WIS)electrolyte by dissolving potassium bis(fluorosulfonyl)amide(KFSI)in water with an ultra-high mass molar concentration of 37 mol/kg.The highly concentrated electrolyte can achieve a wide ESW of 2.8 V.The WIS electrolyte enables a safe carbon-based symmetrical supercapacitor to operate stably at 2.3 V with an ultra-long cycle life and excellent rate performance.The energy density reaches 20.5 Wh/kg at 2300 W/kg,and the capacity retention is 83.5%after 50,000 cycles at a current density of 5 A/g.This new electrolyte will be a promising candidate for future high-voltage aqueous supercapacitors.

Li-rich channels as the material gene for facile lithium diffusion in halide solid electrolytes

Halide solid electrolytes have attracted intense research interest recently for application in all-solid-state lithiumion batteries. Herein, we present a systematic first-principles study of the Li3MX6 (M: multivalent cation;X:halogen anion) halide family that unveils the link between Li-rich channels and ionic conductivity, highlightingthe former as a material gene in these compounds. By screening a total of 180 halides for those with highthermodynamic stability, wide electrochemical window, low chemical reactivity, and decent Li-ion conductivity,we identify seven unexplored candidates for solid electrolytes. From these halides and another four prototypecompounds, we discover that the facile Li diffusion is rooted in the availability of diffusion pathways which canavoid direct connection with M cations-that is, where the local environment is Li-rich. These findings shed lighton strategies for regulating cation and anion frameworks to establish Li-rich channels in the design of high-performance inorganic solid electrolytes.