Modification of LiNi0.8Co0.15Al0.05O2 using nanoscale carbon coating

Abstract

Two different carbon sources, sucrose and glucose, were used as raw materials for constructing a nanoscale carbon coating on the surface of LiNi0.8Co0.15Al0.05O2 (NCA). They were mixed with a certain mass ratio and then were annealed to form a nanoscale even coating, which showed a C@NCA shell-core structure. The core layer was NCA and the shell layer was nanoscale carbon coating. The cathode coating material using nanoscale carbon layer has better electrical conductivity and high diffusivity of Li-ion. It can effectively reduce the mechanical stress, prevent the formation of micro-cracks on secondary particle surface and maintain the integrity of the cathode material. Obtained by comparison, the results show that the material with sucrose as carbon source has better performance. When the mass ratio of coating is 1%, it has the best electrochemical performance. The initial discharge specific capacity is 250 mAh / g at the current density of 0.1C. The capacity retention rate increased to 88.3% after 200 cycles at current density of 1C, higher than uncoated materials significantly (51.1%). While at current density of 5C, the capacity retention rate increased to 63.7% after 500 cycles, higher than uncoated (46.4%) again.