RESUMO
Rechargeable Mg-ion batteries typically suffer from either rapid passivation of the Mg anode or severe corrosion of the current collectors by halogens within the electrolyte, limiting their practical implementation. Here, we demonstrate the broadly applicable strategy of forming an artificial solid electrolyte interphase (a-SEI) layer on Mg to address these challenges. The a-SEI layer is formed by simply soaking Mg foil in a tetraethylene glycol dimethyl ether solution containing LiTFSI and AlCl3, with Fourier transform infrared and ultraviolet-visible spectroscopy measurements revealing spontaneous reaction with the Mg foil. The a-SEI is found to mitigate Mg passivation in Mg(TFSI)2/DME electrolytes with symmetric cells exhibiting overpotentials that are 2 V lower compared to when the a-SEI is not present. This approach is extended to Mg(ClO4)2/DME and Mg(TFSI)2/PC electrolytes to achieve reversible Mg plating and stripping, which is not achieved with bare electrodes. The interfacial resistance of the cells with a-SEI protected Mg is found to be two orders of magnitude lower than that with bare Mg in all three of the electrolytes, indicating the formation of an effective Mg-ion transporting interfacial structure. X-ray absorption and photoemission spectroscopy measurements show that the a-SEI contains minimal MgCO3, MgO, Mg(OH)2, and TFSI-, while being rich in MgCl2, MgF2, and MgS, when compared to the passivation layer formed on bare Mg in Mg(TFSI)2/DME.
RESUMO
Black phosphorus modified sulfurized polyacrylonitrile (BP-SPAN) is reported for the first time for Li-S batteries operated in ether electrolyte. The amorphous P2S5+x in BP-SPAN is crucial to suppress the shuttling effect of polysulfides and enhance the reaction kinetics. It delivers an amazing capacity of 1086 mA h g-1 (2C) and capacity retention of 91.1% (0.1C, 100th).
RESUMO
TiNb2O7 (TNO) has been regarded as a promising anode material for high-power lithium-ion batteries because of the high theoretical capacity and rate performance within the operation voltage range of 1.0-3.0 V. Herein, the electrochemical performance and interface evolution of TNO are comprehensively investigated by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The prepared TNO shows a high initial reversible capacity of 256 mA h g-1 and a satisfactory capacity retention of 68.4% after 200 cycles at 0.1 C. It is generally believed that the formation of solid electrolyte interface (SEI) film could be avoided at the high operating voltage beyond 1.0 V. However, we find that the thin SEI layer is formed during the lithium insertion process and partially dissolved during the following lithium extraction process, and subsequently the SEI layer increases gradually during long-term cycles. Most importantly, we find obvious gassing behavior in the TNO/LiFePO4 pouch cell for the first time and demonstrate effective suppression effects of VC additive on the swelling phenomenon of full batteries.
RESUMO
Wide application of carbon dioxide (CO2) electrochemical energy storage requires catalysts with high mass activity. Alloy catalysts can achieve superior performance to single metals while reducing the cost by finely tuning the composition and morphology. We used in silico quantum mechanics rapid screening to identify Au-Fe as a candidate improving CO2 reduction and then synthesized and tested it experimentally. The synthesized Au-Fe alloy catalyst evolves quickly into a stable Au-Fe core-shell nanoparticle (AuFe-CSNP) after leaching out surface Fe. This AuFe-CSNP exhibits exclusive CO selectivity, long-term stability, nearly a 100-fold increase in mass activity toward CO2 reduction compared with Au NP, and 0.2 V lower in overpotential. Calculations show that surface defects due to Fe leaching contribute significantly to decrease the overpotential.