Cesium doping to improve the electrochemical performance of layered Li1.2Ni0.13Co0.13Mn0.54O2 cathode material.

Aiming to improve the rate capability and cycling stability, cesium doped Li-rich cathode materials Li 1.2-x Cs x Ni 0.13 Co 0.13 Mn 0.54 O 2 (x = 0, 0.012, 0.036, 0.060, 0.096) are synthesized by a sol-gel method and a subsequent calcination process. The optimal Cs+ content is found to be x = 0.060. After Cesium doping to Li+ sites, the enlarged interplanar spacing of (003) plane, which is confirmed by high resolution transmission electron microscopy, can accelerate the Li+ diffusion during the lithiation/delithiation process at the interface of electrode/electrolyte. The obtained Cs-doped Li-rich sample with x = 0.060 exhibits much improved electrochemical performance compared with the bare, especially the rate capability (148 mAh g−1 compared to 50 mAh g−1 at 10 C). The first discharge capacity is much enhanced from 250 to 281 mAh g−1 at 0.1 C with a heightened coulombic efficiency from 72% to 81%. XRD, SEM, TEM, elemental mapping, EDS and ICP-AES are adopted to characterize the morphologies and structures. • Cesium is successfully doped to Li+ sites in Li-rich cathode material. • Both rate and cycling properties are enhanced for Li 1.14 Cs 0.06 Ni 0.13 Co 0.13 Mn 0.54 O 2. • A variety of techniques are adopted to elucidate the improvement mechanism. [ABSTRACT FROM AUTHOR]