Effect of heat pre-treatment conditions on the electrochemical properties of mangrove wood-derived hard carbon as an effective anode material for lithium-ion batteries

Anodic hard carbon for lithium-ion batteries with high discharge capacity was successfully developed using mangrove green tree as a cheap raw material. To obtain commercial-level first-cycle Coulombic efficiency, the effects of heat pre-treatment in the low temperature range of 450-600 °C at various pressures, to produce optimized char precursor before carbonization, were closely investigated, focusing on synthetic yield, structural and physical properties, first-cycle Coulombic efficiency, and discharge capacity of the resulting hard carbon. The hard carbon with heat pre-treatment involving optimum fabrication conditions of 500 °C in inner gas at 0.7 MPa for 39 days exhibited higher synthetic yield of 30.0 wt% and better first-cycle Coulombic efficiency of 81% and discharge capacity of 424 mAh/g than that prepared through direct one-step carbonization, due to low H/C and Odiff/C ratios and a pore structure promoting lithium-ion insertion/desertion.