The full gradient design in Li-rich cathode for high performance lithium ion batteries with reduced voltage decay

Li-rich nickel cobalt manganese oxides (LNCM) cathode with full gradient compounds is prepared by using an ethanol assisted co-precipitation method. The rationally designed procedure involves gradient distributions of transition-metal ions, in which the Ni content increases continuously, Mn content decreases gradually and Co keeps at a low level. The employing ethanol during the synthesis adjusts the surface state to further improve the rate performance of the sample. The full gradient cathode not only provides superior cycling capacity, but also improves operating voltage and mitigates voltage decay due to the high Ni/Mn ratio of out layer with decreased Li2MnO3. The prepared material exhibits high specific capacity of 213.1 mAh g−1 after 100 cycling with voltage decay per cycle about 3.36 mV at 1 C. Even more notably, the voltage decay during cycling could still be significantly limited at high rates and capacity retention rates of 84% and 75% can be reached after 100 cycling at 2 C and 5 C, respectively. Hence, this state-of-art full gradient cathode provides an interesting model to promote a further application of LNCM.