Improved performances of a LiNi0.6Co0.15Mn0.25O2 cathode material with full concentration-gradient for lithium ion batteries

Abstract

A novel high capacity cathode material with a full concentration-gradient (FCG) structure has been successfully synthesized by a modified hydroxide co-precipitation method. A continuous concentration change of Ni, Co, and Mn from the core LiNi_0.8Co_0.1Mn_0.1O₂ to the shell LiNi_0.4Co_0.2Mn_0.4O₂ in each particle with an average composition of LiNi_0.6Co_0.15Mn_0.25O₂ is confirmed by EDX and ICP, respectively. Charge–discharge tests demonstrate that the FCG cathode delivers a high specific capacity of 190 mA h g⁻¹ at a current density of 0.05 mA cm⁻², exceptional rate capacity (a high capacity of 125 mA h g⁻¹ at an ultrafast rate of 10C-rate), and an ultralong cycle life up to 1000 cycles (capacity retention of 80% at 5C-rate), which is obviously superior to the conventional cathode LiNi_0.6Co_0.15Mn_0.25O₂. Meanwhile, the Mn-rich in the outer layer of the FCG cathode contributes to more excellent thermal stability than the conventional cathode LiNi_0.6Co_0.15Mn_0.25O₂.