Most electrolytes for rechargeable Mg batteries require time-consuming conditioning or precycling process to achieve a fully reversible Mg deposition/dissolution, which hinders the normal operation of Mg batteries. This study details a simple and effective method for eliminating this conditioning behavior using heptamethyldisilazane (HpMS) as an electrolyte additive. It was found that the HpMS additive greatly increases the current density and Coulombic efficiency of Mg deposition/dissolution from the initial cycles in various sulfone and glyme solutions containing MgCl 2 or Mg(TFSI) 2 . The beneficial effect of HpMS was ascribed to its ability to scavenge trace water in the electrolytes and remove Mg(OH) 2 and Mg(TFSI) 2 -decomposition products from the Mg surface. Considering its applicability for a wide range of Mg electrolytes, the use of HpMS is expected to accelerate the development of practical Mg batteries.
We report the interfacial study of a silicon/carbon nanofiber/graphene composite as a potentially high-performance anode for rechargeable lithium-ion batteries (LIBs). Silicon nanoparticle (Si)/carbon nanofiber (CNF)/reduced graphene oxide (rGO) composite films were prepared by simple physical filtration and an environmentally-friendly thermal reduction treatment. The films were used as high-performance anode materials for self-supporting, binder-free LIBs. Reducing graphene oxide improves the electron conductivity and adjusts to the volume change during repeated charge/discharge processes. CNFs can help maintain the structural stability and prevent the peeling off of silicon nanoparticles from the electrodes. When the fabricated Si/CNF/rGO composites were used as anodes of LIBs, the initial specific capacity was measured to be 1894.54 mAh/g at a current density of 0.1 A/g. After 100 cycles, the reversible specific capacity was maintained at 964.68 mAh/g, and the coulombic efficiency could reach 93.8% at the same current density. The Si/CNF/rGO composite electrode exhibited a higher specific capacity and cycle stability than an Si/rGO composite electrode. The Si/CNF/rGO composite films can effectively accommodate and buffer changes in the volume of silicon nanoparticles, form a stable solid–electrolyte interface, improve the conductivity of the electrode, and provide a fast and efficient channel for electron and ion transport.
Three-dimensionally structured silicon (Si)–carbon (C) nanocomposites have great potential as anodes in lithium-ion batteries (LIBs). Here, we report a Nitrogen-doped graphene/carbon-encapsulated Si nanoparticle/carbon nanofiber composite (NG/C@Si/CNF) prepared by methods of surface modification, electrostatic self-assembly, cross-linking with heat treatment, and further carbonization as a potential high-performance anode for LIBs. The N-doped C matrix wrapped around Si nanoparticles improved the electrical conductivity of the composites and buffered the volume change of Si nanoparticles during lithiation/delithiation. Uniformly dispersed CNF in composites acted as conductive networks for the fast transport of ions and electrons. The entire tightly connected organic material of NG/C@Si and CNF prevented the crushing and shedding of particles and maintained the integrity of the electrode structure. The NG/C@Si/CNF composite exhibited better rate capability and cycling performance compared with the other electrode materials. After 100 cycles, the electrode maintained a high reversible specific capacity of 1371.4 mAh/g.
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