Operando X-ray Diffraction Study of Polycrystalline and Single-Crystal LixNi0.5Mn0.3Co0.2O2

Pouch cells made with single-crystal LixNi0.5Mn0.3Co0.2O2 positive electrodes have recently shown superior capacity retention over equivalent pouch cells made with polycrystalline LixNi0.5Mn0.3Co0.2O2.(1) This paper aims to further understand the cycling behavior of polycrystalline and single-crystal LixNi0.5Mn0.3Co0.2O2 through an operando X-ray diffraction study, which reveals identical trends in lattice parameter evolution and unit cell volume change during cycling for the two materials. In addition, coin-cell cycling experiments used to examine the initial irreversible capacity loss observed for both materials indicate that it is primarily caused by kinetic limitations of lithium intercalation. Additional X-ray diffraction experiments show much higher c-lattice preferred orientation for electrodes made from single-crystal material, and SEM images of the electrodes reveal a shearing effect in single-crystal particles caused by electrode calendaring. (C) The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.