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LiTiO 2 film-coated layered LiNi 0.815 Co 0.15 Al 0.035 O 2 (NCA) material was successfully synthesised through in situ hydrolysis–lithiation to improve electrochemical properties. Herein, NCA was synthesised using solid state reaction, coated by hydrolysis of tetrabutyl titanate and subjected to lithiation process. The optimal molar ratio (LiTiO 2 : NCA) was found to be 1.0 mol%, and the thickness of LiTiO 2 film coated on the surface of NCA of 18 nm was observed through HRTEM images. Compared with pristine NCA, 1.0 mol% LiTiO 2 -coated NCA demonstrated better electrochemical performance with larger capacity of 20 mAh g−1 under 1 C after 100 cycles. Its related capacity retention was 90.8%. The 1.0 mol% LiTiO 2 -coated sample exhibited high discharge capacity of 157.6 mAh g−1 at a current rate of 10 C, whereas the pristine sample only presented 145.3 mAh g−1. The considerably improvement of the rate and cycling properties of the NCA cathode material is achieved using LiTiO 2 as a Li+-conductive coating layer. These new findings contribute towards the design of a stable-structured Ni-rich material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract This work focuses on the recovery of valuable metal from the cathode materials of spent lithium ion batteries to ensure resource recycling and environmental protection. An environmentally friendly process involving reduction roasting and stepwise leaching is proposed to recover Li and Ni, Co, and Mn from spent LiNi x Co y Mn 1-x-y O 2 materials. Suitable leaching conditions are obtained from thermodynamic analysis (Eh-pH diagram). The effects of several factors, such as acid concentration, temperature, leaching time and liquid‒solid ratio, on the leaching efficiency of valuable metals are investigated. Under optimum conditions, the leaching efficiency of Li, Ni, Co, and Mn are as high as 93.68%, 99.56%, 99.87%, and 99.9%, respectively. The kinetic aspect of the acid leaching process is analyzed by shrinking the core model, which suggests a residue layer diffusion process. The reaction activation energies of Ni, Co, and Mn are 29.35 kJ mol−1, 24.00 kJ mol−1, and 23.29 kJ mol−1, respectively. This metallurgic method contributes to environmentally friendly and economical recovery of valuable metals from spent lithium-ion batteries. Highlights • A novel metallurgical method is proposed to recycling spent LiNi x Co y Mn 1-x-y O 2. • The leaching conditions are comprehensively investigated and optimized. • The kinetics and the controlled step of acid leaching process are analyzed. • The active energies of Ni, Co and Mn reacting with H 2 SO 4 are calculated. [ABSTRACT FROM AUTHOR]

Abstract As cathode materials for Li-ion batteries (LIBs), V 2 O 5 , possessing a large-spaced and open layered crystal structure, have attracted considerable attention due to their distinct advantages of high specific capacity, abundant raw materials and low cost. Although low-dimensional nanostructured V 2 O 5 can increase the discharge capacity of LIBs, it still suffers from poor cycling and rate performance due to serious self-aggregation and pulverization. Building micro/nano-structures is a highly promising method to address the above issues. Herein, we propose a facile oxidation strategy to successfully synthesize the unique 3D hierarchical porous sponge-like V 2 O 5 micro/nano-structures (V 2 O 5 -SLMNSs) by using the structure-similar sponge-like VO 2 (B)@C micro/nano-structures as a precursor. Importantly, as-synthesized V 2 O 5 -SLMNSs possess the distinct structural advantages of a robust structure with large surface area and abundant meso/micropores, which are beneficial for achieving a better electrochemical performance. Specific capacity during the second discharge for V 2 O 5 -SLMNSs is 232 mAh/g at 100 mA/g, with 87% of the capacity being maintained after 50 cycles, which is considerably higher than the discharge capacity (190 mAh/g) in the second cycle and the value for the capacity retention (69%) of 1D V 2 O 5 nanoribbons. Thus, as-synthesized V 2 O 5 -SLMNSs are promising cathode materials for the next-generation LIBs. Graphical abstract Image 1 Highlights • Unique 3D sponge-like V 2 O 5 micro/nano-structures (V 2 O 5 -SLMNSs) are synthesized. • V 2 O 5 -SLMNSs possess robust structure, large surface area and conductive frameworks. • V 2 O 5 -SLMNSs exhibit the greatly improved electrochemical performance. [ABSTRACT FROM AUTHOR]