A further electrochemical investigation on solutions to high energetical power sources: isomerous compound 0.75Li(1.2)Ni(0.2)Mn(0.6)O(2)center dot 0.25LiNi(0.5)Mn(1.5)O(4)

An isomerous layered/spinel 0.75Li(1.2)Ni(0.2)Mn(0.6)O(2)center dot 0.25LiNi(0.5)Mn(1.5)O(4) cathode material with outstanding electrochemical properties has been synthesized by a reasonable design of introducing high-power spinel LiNi0.5Mn1.5O4 material to fill up the surface gaps of pristine lithium-rich layered Li1.2Ni0.2Mn0.6O2 material with a molar ratio of 25 : 75. Morphological characterization reveals that the octahedral spinel LiNi0.5Mn1.5O4 particles are successfully coated into the surface gaps of the Li1.2Ni0.2Mn0.6O2 secondary particle, forming a special alternant structure with spherical and octahedral particles on the surface. Interestingly, some hollow sections are also observed in 0.75Li(1.2)Ni(0.2)Mn(0.6)O(2)center dot 0.25LiNi(0.5)Mn(1.5)O(4) material, confirmed from the TEM images. The structural characterization demonstrates that this isomerous compound is more well-defined a-NaFeO2 configured, more enlarged in Li layer spacing and lower in cation disordered degree. The exquisite morphology and ideal structure endow this nanocrystal-assembled composite significantly enhanced electrochemical performance with high capacity, good rate capability and excellent cycling stability, compared with the pristine Li1.2Ni0.2Mn0.6O2. It delivers a discharge capacity of 135 mA h g(-1) even at an ultrahigh current density of 2000 mA g(-1) (10 C). Moreover, the superior cycling stability is also observed with high discharge capacities of 254 mA h g(-1) and 222 mA h g(-1) at 0.5 C and 1 C after 100 cycles with capacity retention of 98% and 94%, respectively. Moreover, the fast-charging test results are indicative of the fact that this layered/spinel cathode could be used in practical application. Its discharge capacity is 176 mA h g(-1) at 1 C after 50 cycles with the charge rate of 10 degrees C. Furthermore, the composite can endure high current charging and discharging even at a high cut-off potential (5.0 V), whereas the pristine Li1.2Ni0.2Mn0.6O2 material cannot. Therefore, we absolutely believe that this isomerous layered/spinel 0.75Li(1.2)Ni(0.2)Mn(0.6)O(2)center dot 0.25LiNi(0.5)Mn(1.5)O(4) cathode is a promising candidate for the commercial development of advanced LIBs.