Multistage Li1.2Ni0.2Mn0.6O2 Micro-architecture towards High-Performance Cathode Materials for Lithium-Ion Batteries.

Constructing hierarchical-architecture primary nanoparticles that assemble with secondary micro-architectures is very effective to achieve high-performance cathode materials for lithium-ion batteries (LIBs). In this work, well-crystallized lithium-rich layered oxide cathode materials Li_1.2Ni_0.2Mn_0.6O₂ (LNMO) with a micro-architecture was successfully synthesized. The preparation process is divided into two steps: the solvothermal process synthesizes the precursor Ni_0.25Mn_0.75CO₃ (NMCO) and gradient temperature calcination is used to prepare the primary nanoparticles that agglomerate into hierarchical microspheres for final-product LNMO. The as-prepared material was used as cathode materials for LIBs, which exhibit good cycle life and excellent rate performances. The material retains a fairly high discharge capacity of approximately 180 mAh g⁻¹ after 180 cycles at the 2C rate (1C=200 mA g⁻¹). Even after a 50-fold (5C/0.1C) increase, a discharge capacity 61.4 % (153.8 mAh g⁻¹) of the capacity at 0.1C (ca. 249.1 mAh g⁻¹) could be retained. This superior cycle life and rate performance are attributed to the merits of the hierarchical nano-/microsphere structures. [ABSTRACT FROM AUTHOR]