Improving the Structural Ordering and Particle-Size Homogeneity of Li-Rich Layered Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ Cathode Materials through Microwave Irradiation Solid-State Synthesis

Abstract

Li1.2Ni0.13Co0.13Mn0.54O2 (LNCM) has been intensively investigated owing to its high capacity and large voltage window. However, despite its high performance, the synthesis of LNCM can be challenging as it usually contains structural disorders and particle-size inhomogeneities, especially via a solid-state method. This work introduces microwave irradiation treatment on the LNCM fabricated via a solid-state method. The as-treated LNCM has low structural disorders, as indicated by the smaller cation mixing, better hexagonal ordering, and higher c/a ratio compared to the non-treated LNCM. Furthermore, the particle-size homogeneities of as-treated LNCM improved, as characterized by scanning electron microscopy (SEM) and particle size analyzer (PSA) measurements. The improved structural ordering and particle-size homogeneity of the treated sample enhances the specific capacity, initial Coulombic efficiency, and rate capability of the cathode material. The LNCM sample with 20 min of microwave treatment exhibits an optimum performance, showing a large specific capacity (259.84 mAh/g), a high first-cycle Coulombic efficiency (81.45%), and good rate capability. It also showed a stable electrochemical performance with 80.57% capacity retention after 200 cycles (at a charge/discharge of 0.2C/0.5C), which is 13% higher than samples without microwave irradiation.

Keywords

• cycling stability
• facile microwave synthesis
• high-capacity cathode
• lithium-ion battery
• low cation mixing