Preparation of negative electrodes for lithium-ion rechargeable battery by pressure-pulsed chemical vapor infiltration of pyrolytic carbon into electro-conductive forms

The plate-type negative electrodes for lithium-ion rechargeable battery were prepared by pressure-pulsed chemical vapor infiltration of pyrolytic carbon (pyrocarbon) into two sorts of conductive porous forms, that is, the carbonized paper (A) and the TiN-coated paper (B), as the conductive fillers and/or current collectors. The electrodes had the three-dimensionally continuous current paths in the pyrocarbon-based anodes without the organic binders and the additional conductive fillers. The pyrocarbon in sample (A) had the relatively high crystallinity, whereas the pyrocarbon in sample (B) was disordered. Sample (B) possessed higher surface area and larger pore volume with mesopores of 1.5-10nm, especially below 3nm, than that of sample (A). The capacity of pyrocarbon in sample (B) was 460mAhg^-1 per mass of pyrocarbon at a current density of 25mAg^-1, reflecting the disordered microstructure of pyrocarbon film. And 80% of the capacity was maintained even at 1000mAg^-1. The capacity of pyrocarbon in sample (A) was estimated at ∼ 300mAhg^-1, which was lower than that of sample (B). However, sample (A) showed higher Coulombic efficiency at first cycle (i.e. 85%) than that of sample (B), which would result from the high crystallinity, laminar microstructure and low surface area of pyrocarbon in sample (A).