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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]

• Construct Mn 3 O 4 protective shell to alleviate Jahn-Teller distortion. • Oxygen vacancy can effectively restrain the release of oxygen. • The designed LRNMO@Mn 3 O 4 cathode has higher electron/ion conductivity. • The Mn 3 O 4 -coated electrode exhibited excellent cycle stability. Herein, we put forward a feasible interfacial modification strategy in virtue of Mn 3 O 4 surface coating to construct protective shell and alleviate Jahn-Teller distortion during the charge/discharge process. It has been found that the increase of the oxygen vacancy on the surface of Li 1.2 Ni 0.27 Mn 0.54 O 2 of (LRNMO) after Mn 3 O 4 protective layer modification can effectively restrain the release of oxygen and enhancing rate capability, and thus improving its comprehensive electrochemical performances. In particular, the initial coulombic efficiency of the optimized LRNMO-1 electrode is improved from 72.3% to 84.3%. The capacity retention rate is up to 95.6% at 250 mA g−1 (1C) after 200 cycles. In addition, the LRNMO-1 electrode also has a good capacity retention rate (96.4% after 100 cycles) at a high current density of 5C. Moreover, the designed LRNMO@Mn 3 O 4 cathode exhibits higher ionic conductivity and better interface stability. As a result, this work offers a practicable and valuable exploration for the development and industrialization of Co-free Li-rich Mn-based cathode materials with high energy density. [ABSTRACT FROM AUTHOR]

The shortage of lithium resource has become a serious problem due to the ever-increasing demands for lithium-ions batteries (LIBs) in the fields of electric vehicle and grid energy storage. It is imperative to recycle LIBs whether from the perspective of value recovery or environmental protection. Herein, a new method for recovering FePO 4 and Li 2 CO 3 from spent LiFePO 4 cathode materials is proposed. LiFePO 4 was synthesized by carbothermal reduction based on the recovered FePO 4 and Li 2 CO 3. It is well known that LiFePO 4 has poor electronic conductivity and ionic conductivity. In order to improve its electrochemical performance, accelerate the transport speed of lithium ions in the material, and improve its conductivity, a series of samples with different carbon coating contents are prepared. The physicochemical and electrochemical performances are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. The results show that when the carbon is 12 wt% of the LiFePO 4 composite total weight, the sample (LFP-G12) has better electrochemical performance. LFP-G12 has a high initial discharge specific capacity of 146.89 mAh g−1 at 1 C with 97.9% of the initial capacity was retained after 200 cycles. Thus, this paper offers a brand-new way for recycling and directly using the spent LiFePO 4 to prepare LiFePO 4 cathode material. [Display omitted] • Li 2 CO 3 and FePO 4 were recovered from LiFePO 4 by oxidation leaching. • LiFePO 4 was prepared by using raw materials recovered from spent LiFePO 4 battery.. • Carbon coating improves electron/ion conductivity. • LiFePO 4 with carbon coating were obtained by adjusting the dosage of glucose. • The sample of LFP-G12 has good electrochemical performance. [ABSTRACT FROM AUTHOR]