Hollow spherical LiNi_(0.5)Mn_(1.5)O_4 built from polyhedra with high-rate performance via carbon nanotube modification

碳纳米管改性的多面体颗粒自组装中空球状LiNi_(0.5)Mn_(1.5)O_4及其高倍率性能（英文）

Lithium nickel manganese oxide spinel(Li Ni0.5-Mn1.5O4, LNMO) has attracted much attention as the cathode material for rechargeable lithium-ion batteries due to its high energy density and low cost. However, the short cycle life and poor high-rate capability hinder its commercialization. In this study, we synthesized hollow spherical LNMO built from polyhedral particles. The LNMO hollow structure guarantees sufficient contact with electrolyte and rapid diffusion of lithium ions. To enhance the conductivity, we use carbon nanotubes(CNTs) to modify the surface of the cathode. After CNT modification, the LNMO hollow structure manifests outstanding cycling stability and high-rate capability. It delivers a discharge capacity of 127 m A h g-1 at 5 C, maintaining 104 m A h g-1 after 500 cycles. Even at a high rate of 20 C, a capacity of 121 m A h g-1 can be obtained. The excellent electrochemical performance is ascribed to the unique structure and the enhanced conductivity through CNT modification. It is demonstrated that the CNTmodified hollow spherical LNMO is a promising cathode for lithium ion batteries.

本文通过调节烧结温度设计构筑了一种纳米多面体颗粒堆积的中空球状Li Ni0.5Mn1.5O4材料,并进一步通过碳纳米管(CNT)的改性来提高材料的循环性能和高倍率性能.纳米中空结构不仅减少了锂离子的扩散路径,也保证了电解液和正极材料的充分接触,三维网状CNT的改性提高了材料的电子导电率,从而明显改善了材料的循环和高倍率性能.最终得到的LNMO-850/CNT材料在5 C的电流密度下初始容量为127 m A h g-1,500次循环后容量保持在104 m A h g-1.而在20 C的高电流密度下容量仍达到121 m A h g-1,体现了材料优异的循环和高倍率性能.