铌掺杂对镍基正极材料LiNi0.8Co0.1Mn0.1O2电化学性能影响

解决镍基正极材料LiNi_0.8Co_0.1Mn_0.1O₂的电化学循环稳定性和高温循环性能是其产业化推广应用的关键。研究了掺杂铌改性高镍正极材料，优化材料的电化学性能，提升循环稳定性。首先以硫酸盐为原料，在N₂保护气氛下，采用共沉淀法合成三元球形Ni_0.8Co_0.1Mn_0.1（OH）₂前驱体，通过高温固相反应与LiOH·H₂O，Nb₂O₅合成Li（Ni_0.8Co_0.1Mn_0.1）_1-xNb_xO₂（x=0，0.01，0.02，0.03）系列正极材料。X射线衍射结果表明，Nb5+离子可少量进入正极材料晶格，并在正极材料表面形成化学稳定性好的Li₃NbO₄。当x=0.02时，在室温25 ℃，电压2.75~4.2 V，0.2 C倍率下首次放电比容量为172.9 mAh/g，100次循环后容量保持率为97.47%，在50 ℃，0.5 C倍率下循环20次容量基本不变，平均放电比容量为183.7 mAh/g，且该样品具有较好的倍率性能。 

Effect of niobium doping on the electrochemical performance of nickel-based cathode materials

To find out the way to maintain the electrochemical cycle stability and the high-temperature performance of nickel-based cathode materials LiNi0.8Co0.1Mn0.1O2 is the key to its wide application to industry.This paper focuses on the improvement of the electrochemical properties of nickel-based cathode materials by doping niobium.The cathode materials of Li(Ni0.8Co0.1Mn0.1)1-xNbxO2(x=0,0.01,0.02,0.03)were synthesized by calcining the mixtures of LiOH·H2O,Nb2O5 and the ternary material sphericalNi0.8Co0.1Mn0.1(OH)2 precursor which was made from sulphate by co-precipitation method in N2 atmosphere.The XRD results showed that small amount of the Nb5+ions could dope into the cathode materials’lattice and formed Li3NbO4with stable chemical properties on the surface of the cathode materials.When x was 0.02,the special capacity of the first discharge was 172.9 mAh/g and the capacity retention rate was 97.47%after 100 cycles at 25℃,within the voltage range of 2.75~4.2 V and with the ratio of 0.2 C.At 50℃and with the ratio of 0.5 C,the capacity retention rate changed little after 100 cycles and the average discharge specific capacity was 183.7 mAh/g.Moreover,the sample had good rate performance.