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[Display omitted] Benefiting from the extra contribution of O redox, Co-free Li-rich layered oxides (LRNMO) can satisfy the requirement of high specific capacities. However, during the high-voltage charging process, lattice oxygen being oxidized to O− or O 2 leads to a gradual transition of the structure from layered to spinel phase, capacity and voltage decline, hindering the practical application of LRNMO in the lithium-ion battery. Here, a surface modification strategy of Li 1.2 Ni 0.32 Mn 0.48 O 2-δ doped with Ta5+ ions is proposed, in which the Ta5+ ions occupy the lithium sites of the lattice structure on the surface layer of LRNMO and form a Ta 2 O 5 coating layer. The modified electrode exhibits excellent rate performance and cycling stability, with 94.9% and 85.5% capacity retention rate and voltage retention rate, respectively, after 200 cycles at 1C. Moreover, the initial coulomb efficiency and ionic conductivity of the modified electrode are also apparently enhanced. Simultaneously, the decreased Li/Ni mixing degree of the modified electrode reflects the improvement of the structural stability. Therefore, the modification strategy through strong metal–oxygen bonding to integrate the surface structure to regulate the oxygen activity provides a new direction for the design of high energy density Co-free Li-rich cathode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Benefiting from the extra contribution of O redox, Co-free Li-rich layered oxides (LRNMO) can satisfy the requirement of high specific capacities. However, during the high-voltage charging process, lattice oxygen being oxidized to O− or O 2 leads to a gradual transition of the structure from layered to spinel phase, capacity and voltage decline, hindering the practical application of LRNMO in the lithium-ion battery. Here, a surface modification strategy of Li 1.2 Ni 0.32 Mn 0.48 O 2-δ doped with Ta5+ ions is proposed, in which the Ta5+ ions occupy the lithium sites of the lattice structure on the surface layer of LRNMO and form a Ta 2 O 5 coating layer. The modified electrode exhibits excellent rate performance and cycling stability, with 94.9% and 85.5% capacity retention rate and voltage retention rate, respectively, after 200 cycles at 1C. Moreover, the initial coulomb efficiency and ionic conductivity of the modified electrode are also apparently enhanced. Simultaneously, the decreased Li/Ni mixing degree of the modified electrode reflects the improvement of the structural stability. Therefore, the modification strategy through strong metal–oxygen bonding to integrate the surface structure to regulate the oxygen activity provides a new direction for the design of high energy density Co-free Li-rich cathode materials. [ABSTRACT FROM AUTHOR]

Ce-UiO-66 was firstly used as a supercapacitor electrode material and exhibited a high capacitance of 6.9 Fcm−2 in a redox electrolyte. A novel self-supported structure of Ce-UiO-66/TNF was firstly synthesized by growing Ce-UiO-66 on a TNF substrate. This novel Ce-UiO-66/TNF material was proved to possess a high supercapacitive performance in the redox electrolyte of Fe(CN) 6 3−/4−, and it was also the first study for Ce-UiO-66 material on the supercapacitor application. High specific capacitances of 6.9 and 2.5 Fcm−2 can be achieved at large current densities of 20 and 80 mAcm−2, respectively. After 10,000 charge-discharge cycles, the capacitance retention can be kept at 95% and the coulomb efficiency can be maintained over 98%. Such outstanding electrochemical performance may be related to the redox property of the electrolyte, high specific surface area of the Ce-UiO-66 material, porous characteristic of the TNF substrate and self-supported structure of the whole electrode. [ABSTRACT FROM AUTHOR]