A series of high capacity soft carbons with different phosphorus contents were successfully
prepared by carbonizing petroleum cokes treated with hypophosphorous acid at 900°C. The
effect of phosphorus content on the electrochemical performance of the soft carbons was
extensively investigated. The P-doped soft carbons exhibited greatly enhanced discharge
capacities and outstanding rate capabilities with increasing phosphorus content. In addition,
the influence of temperature on the electrochemical behaviors of the soft carbons was
investigated in a wide temperature range of 25°C to 50°C. Surprisingly, the electrochemical
properties of the pristine and P-doped soft carbons were highly sensitive to the operating
temperature, unlike conventional graphite. The pristine and P-doped soft carbons exhibited
significantly high discharge capacities of 470 and 522 mAh/g, respectively, at a high temperature
of 50°C.