论文部分内容阅读
采用溶胶凝胶法,以硫酸铝、异丙醇(IPA)为原料对Li Mn2O4进行包覆。合成了含2%(质量分数)Al2O3表面包覆的Li Mn2O4电极材料。利用场发射扫描电镜(FESEM)对制备材料的形貌进行表征。结果显示,异丙醇协助包覆后材料表面呈现均匀分布的Al2O3颗粒。在55℃,3.0~4.5 V,1C充放电测试表明,IPA协助包覆可以显著提高Li Mn2O4正极材料高温下的循环稳定性。以异丙醇协助的Al2O3包覆Li Mn2O4材料作为正极,100次循环容量保持率为87.3%,而未加异丙醇包覆后的Li Mn2O4材料100次循环容量保持率为82.2%,未经过包覆的材料只有74.1%。不同倍率恒流充放电测试结果表明,异丙醇协助包覆能够改善Li Mn2O4的倍率性能,在5C和10C的放电倍率下的放电比容量分别达到了102.1和91.0 m Ah·g-1。通过电感耦合等离子体质谱仪(ICP)测试样品在电解液中Mn的溶解浓度。结果显示,高温(55℃)储存20 d后,异丙醇协助包覆的Li Mn2O4材料中Mn在电解液中的浓度仅为58.7×10-6,远远低于未加异丙醇包覆的和未经过包覆的。
Sol-gel method was used to coat Li Mn2O4 with aluminum sulfate and isopropyl alcohol (IPA). The LiMn2O4 electrode material with 2% (mass fraction) Al2O3 surface coating was synthesized. The morphology of the prepared material was characterized by field emission scanning electron microscopy (FESEM). The results show that isopropanol assists in the coating of the surface of the material evenly distributed Al2O3 particles. At 55 ℃, 3.0 ~ 4.5 V, 1C charge-discharge test showed that IPA assisted coating can significantly improve the cycle stability of Li Mn2O4 cathode material at high temperatures. The isopropanol-supported Al2O3-coated LiMn2O4 material was used as the positive electrode, the capacity retention rate was 87.3% after 100 cycles, while the LiMn2O4 material without isopropyl alcohol coating had a capacity retention rate of 82.2% after 100 cycles, Only 74.1% of the coated material. The test results of constant rate charge and discharge at different rates show that the isopropanol-assisted coating can improve the rate capability of Li Mn2O4, and the discharge specific capacities at discharge rates of 5 C and 10 C reach 102.1 and 91.0 m Ah · g-1, respectively. The dissolved concentration of Mn in the electrolyte was measured by inductively coupled plasma mass spectrometry (ICP). The results showed that the concentration of Mn in the electrolyte supported by isopropanol-assisted Li Mn2O4 was only 58.7 × 10-6 after storage at high temperature (55 ℃) for 20 d, which was much lower than that without isopropanol And uncoated.