Ultrathin 3 V Spinel Clothed Layered Lithium-Rich Oxides as Heterostructured Cathode for High-Energy and High-Power Li-ion Batteries

摘要

In an attempt to overcome the drawbacks of high-capacity layered lithium-rich cathodes xLi2MnO3·(1-x) LiMO2 (0 ＜ x ＜ 1,M =Mn,Ni,and Co),the spinel clothed layered heterostructured materials,x'Li4MnsO12·(1-x') Li[Li0.2Mn0.ssNi0.1sCo0.1]O2 (x'=0.01,0.03,0.05) have been proposed and synthesized as high-performance cathode materials for high-energy and high-power Li-ion batteries.Based on the characterizations of X-ray diffraction (XRD),transmission electron microscopy (TEM),Raman scattering spectroscopy,it is indicated that ultrathin 3 V spinel Li4Mn5012 has been successfully clothed on the layered lithium-rich cathode.Electrochemical tests demonstrate the sample O.01Li4Mn5O12·0.99 Li[Li0.2Mn0.55Ni0.15Co0.1]O2 with an ultrathin clothing layer of spinel phase,exhibits the highest reversible capacity of 289.4 mAh g-1 and maintains 259.8 mAh g-1 after 80 cycles at 0.1 C rate.Meanwhile,it delivers outstanding rate discharge capacities of 229.4 mAh g-1 at 1 C,216.8 mAh g-1 at 2 C and 184.4 mAh g-1 at 5 C as well as alleviated voltage fade.It is believed the ultrathin clothing spinel layer plays a vital role in the modification of the materials kinetics,and structural and electrochemical stability of the heterostructured cathode.