RESUMEN
Garnet-type solid-state electrolytes have attracted extensive attention due to their high ionic conductivity, approaching 1 mS cm-1, excellent environmental stability, and wide electrochemical stability window, from lithium metal to â¼6 V. However, to date, there has been little success in the development of high-performance solid-state batteries using these exceptional materials, the major challenge being the high solid-solid interfacial impedance between the garnet electrolyte and electrode materials. In this work, we effectively address the large interfacial impedance between a lithium metal anode and the garnet electrolyte using ultrathin aluminium oxide (Al2O3) by atomic layer deposition. Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) is the garnet composition of choice in this work due to its reduced sintering temperature and increased lithium ion conductivity. A significant decrease of interfacial impedance, from 1,710 Ω cm2 to 1 Ω cm2, was observed at room temperature, effectively negating the lithium metal/garnet interfacial impedance. Experimental and computational results reveal that the oxide coating enables wetting of metallic lithium in contact with the garnet electrolyte surface and the lithiated-alumina interface allows effective lithium ion transport between the lithium metal anode and garnet electrolyte. We also demonstrate a working cell with a lithium metal anode, garnet electrolyte and a high-voltage cathode by applying the newly developed interface chemistry.
RESUMEN
Aluminum metal is a promising anode material for next generation rechargeable batteries owing to its abundance, potentially dendrite-free deposition, and high capacity. The rechargeable aluminum/sulfur (Al/S) battery is of great interest owing to its high energy density (1340â Wh kg(-1) ) and low cost. However, Al/S chemistry suffers poor reversibility owing to the difficulty of oxidizing AlSx . Herein, we demonstrate the first reversible Al/S battery in ionic-liquid electrolyte with an activated carbon cloth/sulfur composite cathode. Electrochemical, spectroscopic, and microscopic results suggest that sulfur undergoes a solid-state conversion reaction in the electrolyte. Kinetics analysis identifies that the slow solid-state sulfur conversion reaction causes large voltage hysteresis and limits the energy efficiency of the system.
RESUMEN
Mg metal is a promising anode material for next generation rechargeable battery due to its dendrite-free deposition and high capacity. However, the best cathode for rechargeable Mg battery was based on high molecular weight MgxMo3S4, thus rendering full cell energetically uncompetitive. To increase energy density, high capacity cathode material like sulfur is proposed. However, to date, only limited work has been reported on Mg/S system, all plagued by poor reversibility attributed to the formation of electrochemically inactive MgSx species. Here, we report a new strategy, based on the effect of Li(+) in activating MgSx species, to conjugate a dendrite-free Mg anode with a reversible polysulfide cathode and present a truly reversible Mg/S battery with capacity up to 1000 mAh/gs for more than 30 cycles. Mechanistic insights supported by spectroscopic and microscopic characterization strongly suggest that the reversibility arises from chemical reactivation of MgSx by Li(+).
