Hollow spherical LiNi0.5Mn1.5O4 built from polyhedra with high-rate performance via carbon nanotube modification

Abstract

Lithium nickel manganese oxide spinel (LiNi0.5Mn1.5O4, 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 mA h g−1 at 5 C, maintaining 104 mA h g−1 after 500 cycles. Even at a high rate of 20 C, a capacity of 121 mA 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 CNT-modified hollow spherical LNMO is a promising cathode for lithium ion batteries.