Atomically ordered and epitaxially grown surface structure in core-shell NCA/NiAl2O4 enabling high voltage cyclic stability for cathode application

The Ni-rich layered oxide (NLO) cathode materials play a key role in developing high-energy-density lithium ion battery (LIB) for wide scale deployment of clean transportation technologies. However, surface reconstruction from a layered structure to a mixed spinel/rock-salt structure during charge/discharge cycles is related to the severe voltage decay and capacity fading of the stoichiometric NLO cathode materials, thus thwarting the practical implementation. Herein, we report a heterostructured NLO cathode that tackles the structural degradation and related voltage decay problems. The efficient internal incore volumetric heating by direct coupling of microwave energy induces formation of Ni, Co-rich core and Al-rich shell. As a result of the encapsulation of the atomically ordered NiAl2O4 after heat treatment, the solid/electrolyte interphase and surface structure of NLO cathode remains stable. By applying this NiAl2O4/NLO heterostructured material as a cathode, we demonstrate its robustness in suppressing the voltage decay (0.8% after 100 cycles) during high-voltage cell operation. Rather than the typical modifications, our work explores a more efficient structure engineering process for applications in nano-/micro-manufacturing transition-metal based electrode materials and sheds light on developing high-performance LIB in the near future. (C) 2019 Elsevier Ltd. All rights reserved.