高能量密度LiMn0.6Fe0.4PO4/C的制备及其电化学性能

以Mn(NO_3)_2、Fe(NO_3)_3·9H_2O、NH_4H_2PO_4、LiOH·H_2O为原材料,采用改进的溶胶凝胶法制备了具有高能量密度的Li Mn_(0.6)Fe_(0.4)PO_4/C材料。该方法通过金属和多种配体配位构筑的框架,把得到的一次纳米颗粒构筑为类球形的二次颗粒,即发挥了纳米材料优异的电化学性能,又提高了材料的压实密度,电池的能量密度可提升约30%。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、交流阻抗谱(EIS)、振实密度、粒度以及电化学测试等表征手段对材料的晶体结构、形貌和电化学性能进行了较系统的研究,结果表明此方法制备的LiMn_(0.6)Fe_(0.4)PO_4/C材料不仅具有较高的振实密度和电压平台,还具有优异的电化学性能:振实密度为1.3 g·cm~(-3),且在1C倍率下,放电中值电压为3.85 V,100次循环后,比容量仍有142.3 mAh·g~(-1),容量保持率为99.4%。

Preparation and Electrochemical Performance of LiMn0.6Fe0.4PO4/C with High Energy Density

The LiMn_0.6Fe_0.4PO₄/C materials with high energy density have been prepared successfully by improved sol-gel method, using Mn(NO₃)₂, Fe(NO₃)₃·9H₂O, NH₄H₂PO₄ and LiOH·H₂O as main raw materials. The primary nanoparticles were constructed into secondary particles by the framework of metal and ligand complexes, and the obtained cathode materials showed excellent electrochemical performance and rather high energy density. The energy density of batteries could be increased by 30%. The crystal structure, morphology and electrochemical performance of the materials were systematically characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), electrochemical impedance spectroscopy (EIS), tap density, particle size and electrochemical tests. The results showed that LiMn_0.6Fe_0.4PO₄/C not only has high tap density and median voltage, but also has excellent electrochemical performances. The tap density was 1.3 g·cm^-3. The median voltage of discharge was 3.85 V at 1C, the capacity still achieved 142.3 mAh·g^-1 after 100 cycles.