Anode property of boron-doped graphite materials for rechargeable lithium-ion batteries

摘要

Anode properties of boron-doped graphites were investigated by means of electrochemical measurements. A dischargt capacity of about 315 mAh/g was obtained for 3.8 mass boron-doped pitch coke-derived graphite in galvanostati( measurements. Increased discharge capacity for boron-doped graphite compared with boron-free one was considered to bt mainly due to the enhanced graphitization by boron. Also, in this measurements, a shoulder was observed at 1.3 V (vs Li/Li + ) in boron-doped graphites. This peculiar reaction was confirmed to be the diffusion control and reversible process b) the cyclic-voltammogram measurements, and it occurred before intercalation of lithium-ion into graphite-layers in chargt process and after deintercalate of lithium-ion from graphite layers in discharge process. These phenomena are inferred to be explained as that the lithium atom can be trapped easily to boron solid-solution phase due to the valence band hole created by boron. This capacity existed at high potential is probably worthwhile for the utilization as the signal of the ending oJ discharge process to prevent over-discharging in rechargeable lithium-ion batteries.