炭黑包覆Al_2O_3掺杂LiMn_2O_4正极材料的研究

Study on Carbon Black Coated LiMn_2O_4 Cathode Materials Doped with Al_2O_3

使用醋酸锂、醋酸锰和氧化铝为原料,采用高温固相法合成掺杂Al离子的LiMn2O4二级产物。合成化学计量比为n(Li)∶n(Mn)∶n(Al)=1.3∶1.9∶0.1。首次烧结温度450℃,烧结时间4h;二次烧结温度750℃,煅烧时间为40h。合成样品采用XRD进行材料表征。测试结果表明:合成样品为尖晶石结构,结晶度较高。所得样品使用炭黑包覆处理,并制成实验性电池,对其进行交流阻抗测试(EIS)分析、循环伏安特性(CV)测试、充放电及循环性能测试分析。实验结果表明:包覆后的正极材料改善了LiMn2O4的大电流充放电性能,该材料在0.5C的首次放电比容量为93mAh/g;包覆材料增强了在大电流充放电下的容量保持率,极大地改善了电池的循环性能,该材料在充放电倍率为0.2C时,32次循环后的容量保持率为92.5%。

Using lithium acetate,manganese（Ⅱ） and aluminum oxide acetate as raw materials with stoichiometric ratio of n（Li）：n（Mn）：n（Al）=1.3：1.9：0.1,secondary products of LiMn2O4 doping Se ions were synthesized by high temperature solid phase.For the first time,the sintering temperature was 450 ℃ and the sintering time was 4 h,while the sintering temperature became 750 ℃ and calcining time became 40 h for the second time.At the same time,the samples synthesized were characterized by XRD.The test and result indicated that the samples synthesized are spinel structure with high degree of crystallinity.Then the samples were coated with carbon black and assembled into experimental battery which was measured and analyzed by AC impedance（EIS）,cyclic voltammetry （CV）,charge-discharge and cycle performance.The experimental results showed that the coated materials of which the initial discharge capacity under 0.5C is 93 mAh/g can improve the high current charge-discharge performance of LiMn2O4.On the other hand,it enhances the high current charge-discharge capacity retention rate and greatly improves the cycle performance of the battery.While the charge-discharge rate is 0.2C,the capacity retention rate is 92.5 % after 32 cycles.