Abstract
Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; however, low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. Here we report a large area (approximately 15 cm × 2.5 cm) self-standing anode material consisting of molecular precursor-derived silicon oxycarbide glass particles embedded in a chemically-modified reduced graphene oxide matrix. The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The paper electrode (mass loading of 2 mg cm−2) delivers a charge capacity of ∼588 mAh g−1electrode (∼393 mAh cm−3electrode) at 1,020th cycle and shows no evidence of mechanical failure. Elimination of inactive ingredients such as metal current collector and polymeric binder reduces the total electrode weight and may provide the means to produce efficient lightweight batteries.
Highlights
Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application
Additional advantages include weight savings of up to 10% of the total battery weight[7], if the electrode is prepared in the freestanding form, improved corrosion resistance, and enhanced flexibility, for bendable, implantable, and roll-up electronics. In spite of these advantages, graphene-paper electrodes do not offer an absolute solution because of the following associative disadvantages: (a) potential limiting of overall battery capacity due to insufficient active mass, (b) expensive techniques required for synthesis of Li-redox components and (c) more important, paper anodes generally show very high first cycle loss (50–60%), low cycling efficiency (95–98%) and poor capacity retention at high current densities[23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39], making graphene-paper electrodes somewhat impractical for use in an Li-ion battery fullcell
As an attractive solution to screen printed electrodes, we present our results related to fabrication of a well-organized, interleaved, freestanding, large-area composite anode consisting of SiOC particles supported by crumpled reduced graphene oxide matrix
Summary
Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. What’s more, a particle-based electrode’s long-term cyclability hinges on the inter-particle electrical connection and particle adhesion to the metallic substrate, which decreases rapidly with increasing charge/discharge cycles, for thick high-loading electrodes[9] In this context, the graphene-based multicomponent composite anodes are an attractive alternative to traditional (binder and carbon-black) designs, because of graphene’s superior electronic conductivity, mechanical strength and ability to be interfaced with Li active redox components, such as particles of Si, Ge, and transition metals sulfides/oxides resulting in electrodes that are intrinsically conducting and promote faster ion diffusion[14] À 38. Very few studies have been performed to investigate the mechanical and fracture properties of composite paper-based electrodes
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