Operando X-ray Diffraction Study of Polycrystalline and Single-Crystal Li_xNi_0.5Mn_0.3Co_0.2O₂

Pouch cells made with single-crystal Li x Ni 0.5 Mn 0.3 Co 0.2 O 2 positive electrodes have recently shown superior capacity retention over equivalent pouch cells made with polycrystalline Li x Ni 0.5 Mn 0.3 Co 0.2 O 2 . 1 This paper aims to further understand the cycling behavior of polycrystalline and single-crystal Li x Ni 0.5 Mn 0.3 Co 0.2 O 2 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.