Insight into Nb-sbustitution effects on Li1.17Mn0.57Ni0.24Nb0.02O2 cathode material for lithium-ion batteries application

Abstract

Lithium-rich layered oxides (LLOs) have been intensively studied due to their high energy density, but still face the drawbacks such as capacity decay and voltage decay, and poor cycling stability. In this work, the Nb substituted Li1.17Mn0.57Ni0.24Nb0.02O2 (LMN-Nb) is successfully prepared, and the effects of Nb substitution on the microstructure, voltage attenuation, cycling stability and electrochemical kinetics are characterized and investigated compared with the host material Li1.17Mn0.58Ni0.25O2 (LMN). A proper amount of Nb substitution not only extends the interlayer spacing and increases conductivity of LMN-Nb, but also inhibits the release of lattice oxygen, the migration of transition metal ions into lithium layer and the dissolution of transition metal ions in the electrolyte. As a result, LMN-Nb exhibits significantly improved initial coulombic efficiency, specific capacity and excellent cycling stability (99.1 % remaining after 150 cycles at 2C rate). In addition, the LMN-Nb also shows good electrochemical performance in pouch-type cell (full cell). This results demonstrate that the strategy of using 4d/5d transition metals substitution to design high-performance LLOs is feasible in the following work.