| Lithium rich layered oxides are the ideal cathode materials for lithium ion battery, owing to its high capacity and cheap raw materials, with the blossom of new energy vehicle. The Li2 Mn O3 unit of the lithium rich materials is responsible for stabilize structure rather than lithium deintercalation and intercalation at voltage lower than 4.5 V(vs. Li/Li+), and Li2 Mn O3 acts as the additional capacity source, which can exceed 200 m A h g-1, when charging above 4.5 V. Therefore, to push into market in large scale, it has plenty of choke point to overcome. Increase Ni content to perfect cobalt-free lithium rich materials’ cycling performance under 4.35 V, likewise catering for the window of electrolyte electrochemical stability. This study is based on the aforementioned feature, by the means of introducing Li Ni O2 unit to increase Ni content, optimize the electrochemical performance at 4.35 V. In the present work, Li[Li(1-x)/4Nix Mn3(1-x)/4]O2 with the Ni content, varies from 0.3 to 0.5 are prepared, and we investigated the influence to the structure and behavior result from Ni content, as following:(1) The series precursors of nickel manganese hydroxide are increasing the percentage of exposed(001) active planes. For synthesizing higher Ni content optimum sintering temperature varies from 950°C to 830°C. The XPS shows that the predominant oxidation states of Mn in the compound are Mn4+ and Ni in the compound are Ni2+ and Ni3+, respectively, and the higher Ni content, the more Ni3+, which coincide with the variation of Ni content.(2) As the Ni content increased, full cells utilizing this as-prepared optimum sample materials as the cathode generate specific discharge capacity 128.4, 139.2, 146.0 m A h g-1, respectively, at 4.35 V, 0.5C, and with barely decay. With the Ni content increased, Li2 Mn O3 units content decrease, and capacity are increased: samples generate high specific discharge capacity 245.2, 228.8, 213.7 m A h g-1, capacity retention ratio 95.6%, 93.8%, 89.7%, respectively. at 4.6 V, 0.1C, after 50 cycles. The sample with higher Ni content has lower high temperature and rate performance. The electrochemical behavior of lithium rich materials is promoted at 4.35 V.(3) Li1+y[Ni0.36Mn0.64]1-y O2 cathode materials were synthesized with the same Ni, Mn ratio precursor as Li[Li0.175Ni0.3Mn0.525]O2. The effects of lithium content on the performance were studied, the sample of y= 0.175 shows the best capacity and other properties. For Li2 Mn O3 doped cathode materials transform into spinel phase during the cycling.(4) Li Ni0.57Mn0.43O2 were synthesized with the same Ni, Mn ratio precursor as Li[Li0.125Ni0.5Mn0.375]O2. By comparison, Lithium rich sample presents better peculiarity than the other in layered structure, cycling performance, and charge transfer process resisiance. Capacity retention ratio of lithium rich materials is 99.1% after 100 cycles at 4.35 V. Furthermore, XRD data indicates that the layerd structure of lithium rich sample has no negative effects after cycling. The study emphasizes that, for Li2 Mn O3 doped stabilizes layered nickel and manganese oxide cathode materials and improve the cycling performance.
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