Structural design of high-performance Ni-rich LiNi0.83Co0.11Mn0.06O2 cathode materials enhanced by Mg2+ doping and Li3PO4 coating for lithium ion battery.

Abstract Li3PO4 coating Li0.98Mg0.01Ni0.83Co0.11Mn0.06O2 (NCM83-MP) composite powders are successfully synthesized by first doping Mg2+ into LiNi0.83Co0.11Mn0.06O2 by co-calcination processes and followed by H3PO4 modifying the obtained Li0.98Mg0.01Ni0.83Co0.11Mn0.06O2 composite powders by sol-gel methods. Related physicochemical characterization results demonstrate that Mg2+ doping can significantly enlarge the lattice space along the c-axis to 14.1431 A and lower the Li/Ni mixing degree to 1.58 %, and H3PO4 modifying can effectively reduce the residual lithium content and generate a homogeneous Li3PO4 covering with a thickness of about 11.7 nm on the surface of the composite particles. Furthermore, the battery performance tests indicate that the coin cells assembled with NCM83-MP can exhibit excellent cycling performance, in which the distinguished discharge specific capacity of 157.4 mAh g-1 at 2.0 C at 25 °C after 200 cycles and 154.6 mAh g-1 at 2.0 C at 60 °C after 100 cycles are amazingly retained, respectively. Additionally, the electrode can present a smaller gap of redox peaks of 0.10 V and a lower resistance value of 193.8 Ω compared to the ones of 0.49 V and 451.8 Ω of NCM83-0 after cycles. Those enhanced electrochemical properties are mainly ascribed to the synergetic effect of Mg2+ doping and H3PO4 modifying, which can not only stabilize the lattice structure but also provide fast transfer channels to facilitate Li ions migrating. Therefore, the proposed strategy may excavate new ideas to the further investigation of high-performance Ni-rich cathode materials for lithium ion battery.