Electrochemically fabricated SnO2@PANI binder-free anode for lithium-ion batteries

초록

Recently, as fossil fuel depletion, environmental pollution, and global warming have occurred around the world, intensive research is carried out on green energy sources and energy storage devices. Graphite, which is the most widely used as anode material for commercial lithium-ion secondary batteries (LIBs), has several benefits such as abundant reserves, charge-discharge cycle stability, and low production cost. However, as the use of LIBs expands from portable electronic devices to large-scale energy storage systems (ESS) and electric vehicles (EV), the graphite with a relatively low theoretical capacity of 372 mAh g-1 cannot meet the increasing demand for such applications. Furthermore, the sluggish Li+ diffusion coefficient, and safety issues that arise from the formation of lithium dendrites, especially under the operating conditions of high current rates, still require development of a novel negative electrode that can replace graphite, which has not only high power- and energy-density but also exhibits stable cyclability. Among the various candidates that can be used as a next-generation anode materials, SnO2 having the advantage of high theoretical capacity (1494mAh g-1) and low price is evaluated as a promising anode material for the next-generation LIBs. Nevertheless, the large volume expansion (~300%) leading to formation of unstable solid electrolyte interphase(SEI) layer and the pulverization of electrode during charge-discharge process is an obstacle to be solved for the commercial use in LIBs. In this study, we design a sponge-like SnO2 structure electrodeposited on anodized TiO2 nanotube arrays, which is subsequently electropolymerized with polyaniline(PANi) as a binder-free anode electrode for LIBs. Due to the synergetic effect of a sponge-like structure alleviating the volume expansion and PANi enhancing electrical conductivity, the obtained SnO2@PANi composite as a promising anode electrode for LIBs shows a stable cycle stability and a relativel