Post-mortem Scanning X-ray Diffraction Microscopy of degradation of single particles and Li ionic order in high-voltage LiMn1.5Ni0.5O4 cathode materials

High voltage spinel cathode materials such as LiMn1.5Ni0.5O4 (LMNO) are considered to be the next step in the evolution of lithium-ion battery technology. The main motivations for studying these Co-free materials are their high energy density, fast charging capabilities and low material costs. However, this material widespread use is hindered by its significant degradation problem in particular capacity fade due to Mn dissolution from the surface of the particle. Both operando and post mortem SXDM studies are very well suited to study this phenomenon since it will allow to gather structural information on the strain gradients of the particles. We expect SXDM to give us insight into the interfacial reactions between Jahn–Teller distorted surface lattices and the electrolyte that is responsible for the capacity fade in LMNO. Moreover, the charge/discharge phase transitions of these materials are complex, and poorly understood, which currently limits their rechargeability and commercial viability. The operando BCDI data on strain transformation that takes place inside a single particle would give us valuable information about the change of lithium ionic order and phase evolution at nanoscale.