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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]

Simple and environment-friendly recovery of valuable metals from spent LIBs was explored. The experimental method, which included reduction roasting and hydrometallurgical recovery, is called a quasi-reversible process. The principle behind the quasi-reversible model could be used to assess the energy consumed during the recovery of metals from cathode active materials. The roasting process was analysed using TG–DSC and Kissinger equation. XRD patterns and mass loss ratios were used to investigate the layered LiNixCoyMnzO2 that broke into Li2CO3, MnO, NiO, Ni and Co. Roasting temperature, coke dosage and roasting time were assessed to determine the leaching efficiency of Li, Ni, Co and Mn. Results indicated that the optimum roasting conditions were roasting temperature of 650 °C, coke dosage of 10% and roasting time of 30 min. The roasted products under the optimum parameters were used to leach the valuable metals, and the leaching efficiencies of Li, Ni, Co and Mn were 93.67%, 93.33%, 98.08% and 98.68%, respectively. Li2CO3 solution recovered from water leaching could be utilised to produce Li2CO3 by evaporative crystallisation. Moreover, divalent solution of Ni, Co and Mn obtained via acid leaching without added reducer could be recycled in the co-precipitation of the ternary precursor. [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]

Abstract LiNi 0.5 Co 0.2 Mn 0.3 O 2 (LNCM) was resynthesized by a novel metallurgical approach coupled with solid-state sintering using cathode materials from spent lithium-ion batteries (LIBs) as starting materials. A combination of reduction roasting, two-step leaching, co-precipitation, and solid-state reaction was applied to recover valuable metals and regenerate cathode materials. The prepared LNCM was characterized by a series of physical and electrochemical measurements for comparison with commercial LNCM. X-ray diffraction and scanning electron microscopy results indicate that the resynthesized LNCM exhibits good layered structure and a sphere of approximately 6 μm. The electrochemical tests indicate that the resynthesized LNCM has an initial discharge capacity of 172.9 mA h g-1 (0.2 C) between 2.5 and 4.3 V; the discharge capacity is 160.9 mA h g-1 (0.2 C) after 50 cycles, in which the capacity retention is 93.8%. Cyclic voltammograms and electrochemical impedance spectra detected that resynthesized LNCM has good structural reversibility and conductivity, similar to commercial LNCM. This method is feasible for regenerating the spent cathode material of LIBs, which can contribute to both resource recycling and environmental protection. Highlights • Spent cathode active materials were resynthesized to LNCM by a metallurgy procedure. • Resynthesized LNCM exhibits good layered structure and a sphere of approximately 6 μm. • Resynthesized LNCM has good structural reversibility and conductivity. • Capacities of the prepared LNCM and commercial LNCM was hardly different at any rate. [ABSTRACT FROM AUTHOR]

Rapid developments in revolutionary electric vehicles have led to an increase in the energy-density and cycling-life requirements for Li-ion batteries (LIBs). The binary transition metal oxide NiCo 2 O 4 is attracting considerable attention due to its much larger specific capacity than graphite. However, NiCo 2 O 4 suffers from poor cycling performance owing to a large volume change during cycling. To address this problem, we proposed an easy strategy to fabricate in situ carbon-coated NiCo 2 O 4 bilayered hybrid nanostructural arrays supported on Ni foam (denoted as NiCo 2 O 4 @C BHNAs–NF) as free-standing anodes for LIBs through a sucrose-assisted hydrothermal method. The in situ-synthesized uniform carbon shell can simultaneously buffer the volume change during cycling and increase the conductivity. The micro/nano-structure also possessed outstanding structural advantages, such as large surface area and hierarchical porous characters, enabling NiCo 2 O 4 @C BHNAs–NF to have excellent electrochemical performance. Its capacity can reach 1298 mAh/g at a current density of 100 mA/g, and 86% of the initial capacity can be retained after 100 cycles. All these results revealed that NiCo 2 O 4 @C BHNAs–NF was a promising candidate anode for next-generation LIBs. [ABSTRACT FROM AUTHOR]

As intercalation-type anode materials for Li-ion batteries (LIBs), the commercially used graphite and Li4Ti5O12 exhibit good cycling and rate properties, but their theoretical specific capacities are too low to meet the ever-growing demands of high-energy applications such as electric vehicles. Therefore, the development of new intercalation-type anode materials with larger capacity is very desirable. Herein, we design and synthesize novel 3 D hierarchical porous V2O3@C micro/nanostructures consisting of crumpled nanosheets, through self-reduction under annealing from the structurally similar VO2 (B)@C precursors without the addition of any other reducing reagent or gas. Excitingly, it is found for the first time through ex situ XRD technology that V2O3 is a new, promising intercalation-type anode material for LIBs with a high capacity. V2O3@C micro/nanostructures can deliver a large capacity of 732 mAh g−1 without capacity loss at 100 mA g−1 even after 136 cycles, as well as exhibiting excellent cycling and rate performances. The application of V2O3 for Na-ion batteries (NIBs) is elaborated for the first time, and excitingly, it is found that V2O3@C micro/nanostructures may be promising anode materials for NIBs. [ABSTRACT FROM AUTHOR]

With the wearable electronics progressing rapidly, the demand for flexible, long-life and low-cost electrodes of Li-ion batteries (LIBs) becomes more and more urgent. Due to the abundant resources and low cost, silica (SiO 2 ), especially the amorphous one, has attracted a lot of interests on the application of anode materials for LIBs. However, SiO 2 still suffer from the poor cycling performance mainly caused by the huge volume change during cycling like other alloy-type materials. Furthermore, it remains a challenge to fabricate the SiO 2 –based flexible electrode. Herein, we propose a facile in situ strategy to fabricate the electrospun robust free-standing SiO 2 /carbon nanofibers (denoted as in-SCNFs) film constructed by N-doped carbon nanofibers encapsulating uniformly amorphous SiO 2 nanoparticles. The in situ synthesized finer SiO 2 nanoparticles in the in-SCNFs are uniformly encapsulated in flexible carbon nanofibers, which can effectively buffer the volume change. Furthermore, the robust in-SCNFs film possesses the excellent mechanical flexibility and strength. So, when served as the free-standing anode of LIBs, the in-SCNFs film exhibits superior cycling performance. A discharge specific capacity of 405 mAh/g can be delivered even after a long-term 1000 cycles at a large current density of 500 mA/g, and the retention is up to 115%. It is an exciting finding that the in-SCNFs film is also a long-life anode of Na-ion batteries (NIBs). The 99% of initial capacity can be kept after 250 cycles at 500 mA/g. To our best knowledge, this is the first report on the application of SiO 2 /C composite for NIBs. These results suggest that the as-fabricated in-SCNFs film can become one promising free-standing long-life anode for LIBs and NIBs. [ABSTRACT FROM AUTHOR]

High‐capacity vanadium‐based oxides are one kind of promising energy storage materials, especially for electric vehicles. It has become a hot research issue to synthesize vanadium‐based oxides from low‐dimensional nanostructures to 3D micro/nano‐structures and free‐standing‐electrodes. It will become a very attractive and practical strategy in the future to fabricate the “vanadium oxides‐based cathode/solid electrolyte/Li metal anode‐type” all solid‐state secondary‐ion batteries. This is reported by Pengcheng Liu, Kongjun Zhu, and co‐workers in article number 1700547. [ABSTRACT FROM AUTHOR]

In this study, we adopt a facile two-step annealing strategy to synthesize different structural 3D Fe2O3 micro-cubes and 3D Fe3O4 micro-cubes using Prussian blue (PB) as a precursor. Importantly, the effect of the annealing temperature on the structural evolution of the products is systematically investigated. In the first step, the 3D Fe2O3 cubes are synthesized by annealing PB in air. With the increasing temperature, the morphology of 3D Fe2O3 changes from the cube with pores on surface to the hollow cube assembled by nanosheets (HCNSs), which is caused by the higher gas generation and overflow. In the second step, 3D Fe3O4 cubes are obtained by annealing 3D Fe2O3-HCNSs in the atmosphere of Ar/H2. With the increasing temperature, the morphology of 3D Fe3O4 changes from the hollow cube assembled by nanosheets to the hierarchical porous hollow cube assembled by fine nano-particles (denoted as HCNPs), an interesting micro/nano-structure that is obtained by recrystallization and reduction. When the temperature is excessive, the building blocks become larger and the 3D structures collapse. Furthermore, we evaluate the electrochemical performance of 3D hierarchical porous Fe3O4-HCNPs as the anode materials for Li-ion batteries. They exhibit enhanced electrochemical performance, characterized by a large reversible capacity of 1193.6 mA h g−1 at a current density of 100 mA g−1 and a high rate capacity of 942.1 mA h g−1 at 1000 mA g−1. This superior performance is due to the unique structural advantages of 3D hierarchical porous Fe3O4-HCNPs, including abundant meso/micro-pores, hollow structure and robust structural stability. [ABSTRACT FROM AUTHOR]

Sodium ion batteries are an emerging candidate to replace lithium ion batteries in large-scale electrical energy storage systems due to the abundance and widespread distribution of sodium. Despite the growing interest, the development of high-performance sodium cathode materials remains a challenge. In particular, polyanionic compounds are considered as a strong cathode candidate owing to their better cycling stability, a flatter voltage profile, and stronger thermal stability compared to other cathode materials. Here, we report the rational design of a biomimetic bone-inspired polyanionic Na3V2(PO4)3-reduced graphene oxide composite (BI-NVP) cathode that achieves ultrahigh rate charging and ultralong cycling life in a sodium ion battery. At a charging rate of 1 C, BI-NVP delivers 97% of its theoretical capacity and is able to retain a voltage plateau even at the ultra-high rate of 200 C. It also shows long cycling life with capacity retention of 91% after 10 000 cycles at 50 C. The sodium ion battery cells with a BI-NVP cathode and Na metal anode were able to deliver a maximum specific energy of 350 W h kg−1 and maximum specific power of 154 kW kg−1. In situ and postmortem analyses of cycled BI-NVP (including by Raman and XRD spectra) HRTEM, and STEM-EELS, indicate highly reversible dilation–contraction, negligible electrode pulverization, and a stable NVP-reduced graphene oxide layer interface. The results presented here provide a rational and biomimetic material design for the electrode architecture for ultrahigh power and ultralong cyclability of the sodium ion battery full cells when paired with a sodium metal anode. [ABSTRACT FROM AUTHOR]