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The lithium-ion battery is moving in the direction of high energy density, high-security, high electrochemical performance, the current study focused on the electrode material, electrolyte, separator, and related processes. LiFePO 4 stable structure, rich in resources, good safety performance, non-toxic, environmentally friendly, and the theoretical capacity of up to 170mAh / g. A series of studies have shown that LiFePO 4 has become the most promising one of the cathode material for lithium-ion batteries. But the LiFePO 4 fatal flaw exists, that is, low the LiFePO 4 electronic conductivity and lithium ion diffusion rate of addition LiFePO 4 itself density , resulting in the volume energy density is low, affecting the practical use of this material. LiFePO 4 electrochemical performance: Improved Synthesis of small particle size and uniform distribution of the product; the doped conductive agent, mainly doped with carbon or metal powder; doping metal ions, from the essentially improve the conductivity of the material. From the the doped conductive agent ideologically start sucrose as a carbon source, using the solid-phase method step calcined the LiFePO 4 / C material, using TG / DTA, XRD, EA (element analysis) SEM, CV (cyclic voltammetry), etc. by means of the material were characterized by the electrochemical performance of the material was tested under different conditions. The results showed that the sample obtained by the 650 ° C calcined 24h showed better electrochemical performance, the first discharge capacity under a current density of 10mA / g to 125mAh / g, under a current density of 100mA / g, the initial discharge capacity of 100mAh / g. Rheological phase method has been successfully used for the synthesis of lithium ion battery electrode materials, such as the spinel LiMn 2 O 4 , the layered LiMnO 2 LiNiO 2 ZnCO 2 O 4 and other. Here we rheological phase the synthesized LiFePO 4 / C cathode material, while the introduction of a new carbon source - citric acid. Material exhibits better electrochemical performance, especially in high-rate performance, the first discharge capacity of 121mAh / g, 10 laps capacity as 135mAh / g; 100mA / g current density current density of 10mA / g The initial discharge capacity as 110mAh / g, 100 laps after the capacity is still higher than 100 mAh / g, the carbon doping can effectively improve the conductivity of the material, also studied the electrochemical performance of the material at 55 ℃. The results show that, compared with the solid-phase method, low-the rheological phase roasting temperature, short time, to provide a new method for the synthesis of carbon-doped LiFePO 4 . Of LiFe 1-x the PO 4 charge-discharge process, the Mn x contains two regions, one in the 4.0-4.1V, and the other at 3.5- 3.6V, respectively, corresponding to the Mn 3 / Mn 2 and the Fe 3 / Fe 2 CLP relatively lithium electrode potential, and can therefore act as 4V of the positive electrode material used. The this chapter rheological phase synthesis of a series of LiFe 1-x PO the Mn x 4 / C materials The results showed that X = 0.6 when the material showed better electrochemical performance, low capacity, subject to further optimize the synthesis conditions, to improve its electrochemical properties. Finally, the use of differential scanning calorimetry (differential scanning calorimetry, DSC) discussed several
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