| LiMnPO4 materials have attracted more and more attention for their advantages on simple preparation, low cost and high energy density. However, the application of Li is limited by its intrinsically low conductivity. In this paper, we improved its electrochemical performance through the modified methods of carbon coating and metal ion doping.All the samples were prepared by a nano-milling and spray-drying assisted solid-state process. This preparation process is a promising technique for massive production due to its simple operation and low cost. LiMnPO4/C was first obtained and the influences of ball-milling parameters, calcination temperature and various carbon sources on the particles and performances were discussed. The results showed that when the time for ball-milling is 2h and the solid content is 20%, the ball-milling worked best. Besides, the samples calcined at 750? with caramel as carbon sources showed the best performances.Preparation and study of Fe-doped LiFexMn1-xPO4/C (x=0.2,0.3,0.4,0.5) samples were on the basis of optimized conditions. The results showed that the discharge capacity and energy density at 0.1C were 153mAh g-1 and 570Wh Kg-1, respectively, when the content of Fe doped is 0.4. Then, the Cr-doped LiFe0.4Mno.6-yCryP04/C (y=0.002,0.005,0.01) were prepared and studied by us. The results revealed that the sample with 0.5% Cr doped in the Mn2+ sites achieved the largest discharge capacity (163.6mAh g-') and the best cycling stability with a capacity retention of 99.2% over 30 charge/discharge cycles. Moreover, the sample presented the highest energy density (606Wh kg-1), which could be a great potential high energy density cathode material in lithium-ion batteries. |
PDF Full Text Request