Advanced Concentration Gradient Cathode Material with Two-Slope for High-Energy and Safe Lithium Batteries

Abstract

Li[Ni0.65Co0.13Mn0.22]O-2 cathode with two-sloped full concentration gradient (TSFCG), maximizing the Ni content in the inner part of the particle and the Mn content near the particle surface, is synthesized via a specially designed batch-type reactor. The cathode delivers a discharge capacity of 200 mAh g(-1) (4.3 V cutoff) with excellent capacity retention of 88% after 1500 cycles in a full-cell configuration. Overall electrochemical performance of the TSFCG cathode is benchmarked against conventional cathode (CC) with same composition and commercially available Li[Ni0.8Co0.15Al0.05]O-2 (NCA). The TSFCG cathode exhibits the best cycling stability, rate capability, and thermal stability of the three electrodes. Transmission electron microscopy analysis of the cycled TSFCG, CC, and NCA cathodes shows that the TSFCG electrode maintains both its mechanical and structural integrity whereas the NCA electrode nearly pulverizes due to the strain during cycling.