Improvement of Electrochemical Performance and Thermal Stability by Reducing Residual Lithium Hydroxide on LiNi0.8Co0.1Mn0.1O2 Active Material using Amorphous Carbon Coating

Using LiNi0.8Co0.1Mn0.1O2 as a starting material, a surface-modified cathode material was obtained by coating it with a nanolayer of amorphous carbon, where the added C12H22O11 (sugar) was transformed to Li2CO3 compounds after reacting with residual LiOH on the surface. A thin and uniformly smooth nanolayer (35 nm thick) was observed on the surface of the LiNi0.8Co0.1Mn0.1O2, as confirmed by transmission electron microscopy (TEM). The amount of residual lithium hydroxide (LiOH) was significantly reduced through the formation of lithium carbonate (Li2CO3). As a result, carbon-coated LiNi0.8Co0.1Mn0.1O2 exhibited noticeable improvement in capacity and rate capability and much lower exothermic heat in the charged state at 4.3V. The improved electrochemical performance and thermal stability are attributed to the carbon coating, which reduced the residual lithium hydroxide, protected the cathode material from reacting with the electrolyte, and slowing the incrassation of the solid electrolyte interphase (SEI) film on the surfaces of the oxide particles.C12H22O11 + 12O2 → 12CO2 + 11H2OPACS number: 73.20.At