Li+ and Cl− co-doped LiNi0.5Mn1.5O4 cathode material with truncated octahedral shape and enhanced electrochemical performance for Li-ion batteries

High-voltage spinel Li 1+ x Ni 0.5 Mn 1.5 O 4- x Cl x (0 ≤ x ≤ 0.04) cathode materials with different contents of Li + and Cl − co-doping were obtained through a solid-state process. Scanning electron microscopy and transmission electron microscopy images indicate that pure LiNi 0.5 Mn 1.5 O 4 (LNMO, space group Fd-3 m ) particles possess an octahedral morphology, predominantly exhibiting {111} crystallographic planes. While the specimens with Li + and Cl − co-doping display not only {111} crystal facets but also positive {100} and {110} facets (i.e. truncated octahedral shape) that could facilitate Li + transport and stabilize the spinel structure. Compared to the pure LNMO, the Li + and Cl − co-doped LNMO electrodes display superior electrochemical performances. For example, the Li 1.03 Ni 0.5 Mn 1.5 O 3.97 Cl 0.03 exhibits the superior rate capability, with discharge capacities of 92.3 and 52.6 mA h g −1 at 7C and 10C, respectively, which are much higher than those of pure LNMO (54.2 and 7.8 mA h g −1 at 7C and 10C). An improved electrochemical properties of LNMO-Cl0.03 is attributable to its relatively larger portion of {100} and {110} facets, lower charge-transfer resistance and electrode polarization, and higher Li + diffusion coefficient. • The Li and Cl co-doping not only changes particle morphologies but also make the particle size become slightly larger. • LNMO-Cl0.03 exhibits a superior rate performance and cycling stability than that of pure LNMO. • The relatively larger portion of {100} and {110} facets in LNMO-Cl0.03 may be favorable for Li+ diffusion.