The Preparation And Modification Of Calcium Carbide-Derived Carbon For The Application Of Lithium Lon Battery

Carbide derived carbon is an amorphous porous material, it has many advantages: low cost, narrow pore size distribution, large specific surface area, controlled pore size distribution and friendly to environment etc. Carbide derived carbon has played an increasingly important role in many areas such as gas-storage, carbon coating in tribology and supercapacitor. In this paper, we firstly used carbide derived carbon as anode material and studied its electrochemical performances. We modified CCDC with LiOH, LI2CO3 and H2O2, in order to improve its electrochemical performances.Firstly, CCDC was synthesized from CaC2 in a freshly chlorine which was prepared by manganese dioxide and strong hydrochloric acid in the temperature rang of 400°C-700℃. The results showed that CCDCs were amorphous nanoscaled materials. The specific surface area decreased from 658 m2/g to 201 m2/g and the average pore size increased from 3.766 nm to 3.842 nm with reaction temperature increasing from 400℃to 700℃. The first charge specific capacity of CCDC prepared at 600℃was 335.4 mAh/g, the charge capacities was 266.8 mAh/g after 30 cycles at 0.1 C.In order to reduce the irreversible capacity and improve electrochemical performance of CCDC, CCDC/Li composites were synthesized by using lithium hydroxide (LiOH) and lithium carbonate (Li2CO3) as lithium sources, and the effects of lithium content on the structures and electrochemical performances of CCDC/Li were investigated. The results indicated that addition of lithium did not change the structures of CCDC, but reduced the irreversible capacities and improved the electrochemical performances of CCDC. Compared with the pure CCDC, CCDC/ LiOH and CCDC/Li2CO3 had higher capacities, better cycle performances and reversibility. The first charge specific capacity of CCDC/LiOH composite with 4 wt.% LiOH was 350.9 mAh/g and keeped 266.7 mAh/g after 50 cycles at 0.5 C, the corresponding capacity retention rate of 1-50th was 76.0%. The first charge specific capacity of CCDC/Li2CO3 composite with 2 wt.% Li2CO3 was 355.7 mAh/g and keeped 275.6 mAh/g after 50 cycles at 0.5 C, the corresponding capacity retention rate of 1-50th was 77.5%.At last, the CCDC was modified by the solution oxidation with H2O2, in order to improve the reversible capacity of calcium carbide-derived-carbon. We discussed the effects of various factors such as the concentration of the hydrogen peroxide, oxidation temperature and reaction time. The results showed that CCDC sample oxidated at 2 mol/L,60℃and 4 h, displayed better electrochemical performance. The initial reversible capacity high as 347.4 mAh/g at rate of 0.5 C, and the corresponding capacity retention rates of 50th was 80.5% that after the oxidation treatment with H2O2, some mesoscopic pores/channels and thin oxide layer were introduced on the surface of CCDC. The oxidated CCDC displayed much larger charge capacity, better polarizations than pristine CCDC.