| LiFeP04 cathode materials have the advantages of high working voltage, huge specific capacity, safe, low leakage current, short charge-discharge time and wide working temperature, which is the best choice for driving power source of vehicles. But the low electrical conduction rate and low Li ion dispersing rate limit the discharging characteristics under high multiplying power.In this paper, we used the Fe(NO3)3·9H2O and LiH2PO4 as the reaction material, the 3D-network CA and KB as both hard temples and conductive framework, applying the wet impregnating method, produced a conductional 3D-network LiFePO4/C nanomaterial, and using XRD, SEM, TEM, BJH, Raman, TGA and electrical chemical test to study the structure, electrochemical characteristics and mechanic of this material.The results show that LiFePO4/CA material preserves 3D-network structure as CA, and the LiFePO4 dispersed on the inner wall of CA; LiFePO4/CA material shows the both phenomenon of oxidation-reduction Li storage between FePO4 and LiFePO4 and the interface Li storage; In this LiFePO4/CA material, the LiFePO4 shows the discharge capacity of 157.4, 147.2,139.7,116.3 and 91.8 mAh g-1 under 1C,5C, 10C,20C and 40C. And the specific capacity loss is under 1% after 100 cycles under 1C.We studied the LiFePO4/KB nano material structure and electrochemical characteristics under different carbon ratio. The result shows when the carbon ratio increases, the 3D-network density will decrease, the oxidation-reduction Li storage between FePO4 and LiFePO4 will decrease and the interface Li storage will increase; We found a best carbon ratio of 28% behaves the best electrochemical characteristics, and the discharge capacity is 179, 162,146 and 127mAh/g under 0.2C,1C,5C and IOC.We used the thermal carbon reduction method to synthesis C-LiFePO4/KB nano material, The result shows:the LiFePO4 crystal size will not be affected by different lemon acid dosage; We found a best dosage of n(lemon acid):n(LFP)=1:2 which shows the best electrochemical characteristics. The specific capacity is 161,146,135 and 125mAh/g under 0.1C,1C,5C and 10C. The C-LiFePO4/KB material electrochemical characteristics are almost the same between the sintering atmosphere of pure N2 or N2:H2=9:1 gaseous mixture. |
