快离子导体Li_(1.5)Y_(0.5)Zr_(1.5)(PO_(4))_(3)包覆层对富镍三元正极材料电化学性能的影响

Effect of Fast Ionic Conductor Li_(1.5)Y_(0.5)Zr_(1.5)(PO_(4))_(3)Coating Layer on the Electrochemical Performance of Ni-Rich Ternary Cathode Materials

研发富镍低钴的先进正极材料是目前提高锂离子电池能量密度和降低电池成本的有效办法。然而,随着Ni含量的增加,富镍层状氧化物普遍存在前驱体合成困难、结构不稳定和界面活性高等一系列问题,阻碍了富镍层状氧化物正极材料的市场化推广。本文采用优化的共沉淀法制备出结构稳定的LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NCM811)正极材料,同时在NCM811材料表面均匀包覆快离子导体Li_(1.5)Y_(0.5)Zr_(1.5)(PO_(4))_(3)涂层,以克服富镍层状氧化物界面结构不稳定和易受电解液腐蚀的难题。在4.5 V高截止电压下,改性样品0.2 C的放电比容量为214.2 mAh·g^(-1),10 C的放电比容量高达158.8 mAh·g^(-1),高于原始样品的203.7 mAh·g^(-1)(0.2 C)和82.7 mAh·g^(-1)(10 C)。同时,改性样品在4.3 V下经1 C循环200次后的容量保持率高达84.7%,高于原始样品(61.94%)。

The development of nickel-rich and low-cobalt cathode materials is currently an effective way to improve the energy density and reduce the cost of lithium-ion batteries.However,as Ni content increases,Ni-rich layered oxides have some problems,such as difficult precursor synthesis,structural instability,and high interfacial activity,which hinder the promotion of Ni-rich layered oxide cathode materials.In this paper,a structurally stable LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NCM811)cathode material was prepared by an optimized co-precipitation method,while a fast ionic conductor Li_(1.5)Y_(0.5)Zr_(1.5)(PO_(4))_(3)coating was uniformly wrapped on the surface of NCM811 material to overcome the difficulties of interfacial structural instability and electrolyte corrosion.At a high cut-off voltage of 4.5 V,the discharge specific capacity of the modified sample is 214.2 mAh·g^(-1)at 0.2 C and up to 158.8 mAh·g^(-1)at 10 C,which is much higher than the 203.7 mAh·g^(-1)(0.2 C)and 82.7 mAh·g^(-1)(10 C)of the original sample.Meanwhile,the capacity retention rate of the modified sample after 200 cycles of 1 C at 4.3 V is as high as 84.7%,which is higher than that of the original sample(61.94%).