Natural graphite (NG) was hydrothermally oxidized at room temperature, 100 ºC and 200 ºC respectively to analyze the effects of temperature on the electrochemical performance of the NG as an anode for lithium ion cells. Charge/discharge results showed that the sample treated at 100 ºC exhibited the highest initial intercalation capacity of 340.1 mAh/g and a Coulombic efficiency of 89.9%, while the sample treated at 200 ºC showed the highest capacity retention of 96.5% after 20 charge/discharge cycles. X-ray photoelectron spectra revealed that groups containing oxygen were present on the surface of all samples, which explains why the performance of the sample treated at room temperature shows slightly improved electrochemical performance that can be further improved by increasing the oxidation temperature.
Lithium-ion cell; Anode; Natural graphite; Surface oxidation; Coulombic efficiency
The work was supported by the National Natural Science Foundation of China (No. 20903104) and Binzhou University (No. 2008Y01, No. 2008ZDL04).
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