The controllable morphology and size Li-rich Mn-based layered oxide LiNiCoMnO with micro/nano structure is successfully prepared through a simple coprecipitation route followed by subsequent annealing treatment process. By rationally regulating and controlling the volume ratio of ethylene glycol (EG) in hydroalcoholic solution, the morphology and size of the final products can be reasonably designed and tailored from rod-like to olive-like, and further evolved into shuttle-like with the assistance of surfactant. Further, the structures and electrochemical properties of the Li-rich layered oxide with various morphology and size are systematically investigated. The galvanostatic testing demonstrates that the electrochemical performances of lithium ion batteries (LIBs) are highly dependent on the morphology and size of LiNiCoMnO cathode materials. In particular, the olive-like morphology cathode material with suitable size exhibits much better electrochemical performances compared with the other two cathode materials in terms of initial reversible capacity (297.0 mAh g) and cycle performance (95.4% capacity retention after 100 cycles at 0.5 C), as well as rate capacity (142.8 mAh g at 10 C). The excellent electrochemical performances of the as-prepared materials could be related to the synergistic effect of well-regulated morphology and appropriate size as well as their micro/nano structure.

Layered/spinel heterostructured Li-rich material is prepared by controlling the conditions of a solvothermal method to obtain precursor and the subsequent high-temperature solid phase reaction, and then, 3 wt % LiF, 3 wt % Li2TiO3, and 3 wt % Li3PO4 are coated on the surface of the layered/spinel heterostructured Li-rich oxide by a wet chemical method. The influences of different lithium salt coating layers on the layered/spinel heterostructured material are investigated by transmission electron microscopy, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy. It can be seen that after coating a Li salt layer, the initial charge–discharge efficiency, cycle, and rate performance are obviously improved. Especially, the sample coated with Li3PO4 shows an optimum result in improving the rate capability of layered/spinel heterostructured Li-rich material and effectively inhibiting the side reaction between the layered/spinel heterostructured Li-rich material and organic electrolyte as well as maintaining the structural stability of the material. Therefore, the layered/spinel heterostructured Li-rich material coated with Li3PO4 has the highest rate capability of 148.2 mAh g–1 at 10 C, the best cycle ability with capacity retention of 85.3% cycling 200 times at 0.5 C, and improved initial Coulombic efficiency of 88.3%.

Li-rich material 0.4Li2MnO3·0.6LiNi1/3Co1/3Mn1/3O2 with a layered/spinel heterostructure is synthesized by a simple strategy. On the basis of structure and morphology analyses, it is revealed that the as-prepared Li-rich material possesses both porous micronano structure and integral layered-spinel heterostructure. Moreover, the obtained layered-spinel cathode material possesses prominent electrochemical characteristics, especially its rate capability. The initial discharge capacity of the as-prepared material is 269 mAh g–1 with a high Coulombic efficiency of 90.3%. The material delivers discharge capacities of 239 mAh g–1 at 0.5C, 195 mAh g–1 at 5C, and 175.8 mAh g–1 even at 10C. Also, the capacity retention of the cell is still as high as 80% at high current density (5C) after 200 cycles. The addition of spinel can inhibit the collapse of the material structure and voltage fading upon cycling. The 3D spinel Li4Mn5O12 phase in the Li-rich compound could provide a fast Li-ion diffusion pathway and a porous micronano structure which are key parameters for the remarkable excellent electrochemical performance of the as-prepared cathode material.

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