Charge-discharge properties of surface-modified carbon by resin coating in Li-ion battery

The effect of an epoxy resin coating on the electrochemical performance of Li-ion batteries is investigated. Mesocarbon microbeads (MCMB), which constitute a promising carbon anode material for rechargeable Li-ion batteries is used as a starting carbon material. The surface coating of the MCMB is carried out by refluxing in a dilute H2SO4 solution and mixing in the epoxy resin-dissolved tetrahydrofuran (THF) solution. After heat treatment at 1000-1300 degreesC, the resin coating layer on the MCMB is converted to an amorphous phase which is identified by means of a high resolution transmission electron microscope (HRTEM) and a electron energy loss spectroscopy FEELS) analyses. The Brunauer-Emmett-Teller (BET) surface area of MCMB is increased by the formation of the amorphous epoxy resin coating layer. The electrochemical performance of the MCMB, such as the charge-discharge capacity and cycleability, is enhanced by the surface modification through epoxy resin coating. The reasons for the improvement of electrochemical performance are discussed in terms of the results from HRTEM observation, EELS analysis, and cyclicvoltammetry. (C) 2002 Elsevier Science B.V. All rights reserved.