1 research outputs found
Enhanced Electrochemical Performance of LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> Cathode Material by YPO<sub>4</sub> Surface Modification
Cathode
material LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> (LNMO) for
lithium-ion batteries is successfully synthesized by
a sol–gel method and is further modified by a thin layer of
YPO<sub>4</sub> (1, 3, and 5 wt %) through a simple wet chemical strategy.
Physical characterizations indicate that the YPO<sub>4</sub> nanolayer
has a little impact on the cathode structure. Electrochemical optimization
reveals that the 3 wt % YPO<sub>4</sub>-coated LNMO could still deliver
a high specific capacity of 107 mAh g<sup>–1</sup> after 240
cycles, with a capacity retention of 77.5%, much higher than that
of the pristine electrode. Electrochemical impedance spectroscopy
(EIS) analysis proves that the rapid increase of surface impedance
could be suppressed by the YPO<sub>4</sub> coating layer and thus
facilitates the surface kinetics behavior in repeated cycling. Through
further material aging experiments, the improvement of electrochemical
performances could be attributed to the formation of Lewis acid YF<sub>3</sub>, converted from the YPO<sub>4</sub> coating layer in the
LiPF<sub>6</sub>-based electrolyte, which not only scavenges the surface
insulating alkaline species with a high acidity but also accelerates
ion exchange on the material surface and thus helps to generate the
solid solution Li–Ni–Mn–Y–O on the surface
of YPO<sub>4</sub>-coated LNMO