Phase Transitions in the “Spinel-Layered” Li1+xNi0.5Mn1.5O4 (x = 0, 0.5, 1) Cathodes upon (De)lithiation Studied with Operando Synchrotron X-ray Powder Diffraction

“Spinel-layered” Li1+xNi0.5Mn1.5O4 (x = 0, 0.5, 1) materials are considered as a cobalt-free alternative to currently used positive electrode (cathode) for Li-ion batteries. In this work, their electrochemical properties and corresponding phase transitions were studied by means of synchrotron X-ray powder diffraction (SXPD) in operando regime. Within the potential limit 2.2–4.9 V vs. Li/Li+ LiNi0.5Mn1.5O4 with cubic spinel type structure demonstrates capacity 230 mAh·g?1 associated three first-order significant total volume change 8.1%. The Li2Ni0.5Mn1.5O4 material exhibits similar value subsequence phase, although fraction spinel-type does not exceed 30 wt.%. main component is Li-rich layered oxide Li(Li0.28Mn0.64Ni0.08)O2, which provides nearly half very small unit cell 0.7%. Lower mechanical stress Li (de)intercalation better cycling stability spinel-layered complex makes them more perspective practical applications compared single-phase high-voltage cathode material.