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Recycling high-valuable metal elements (such as Li, Ni, Co, Al and Cu elements) from scrapped lithium ion batteries can bring significant economic benefits. However, recycling and reusing anode material has not yet attracted wide attention up to now, due to the lower added-value than the above valuable metal materials and the difficulties in regenerating process. In this paper, a novel regeneration process with significant green advance is proposed to regenerate anode material recycled from scrapped Li-ion batteries for the first time. After regenerated, most acetylene black (AB) and all the styrene butadiene rubber (SBR), carboxymethylcellulose sodium (CMC) in recycled anode material are removed, and the surface of anode material is coated with pyrolytic carbon from phenolic resin again. Finally, the regenerated anode material (graphite with coating layer, residual AB and a little CMC pyrolysis product) is obtained. As expected, all the technical indexs of regenerated anode material exceed that of a midrange graphite with the same type, and partial technical indexs are even closed to that of the unused graphite. The results indicate the effective regeneration of anode material recycled from scrapped Li-ion batteries is really achieved.

A new green recycling process (named as direct regeneration process) of cathode material mixture from scrapped LiFePO4 batteries is designed for the first time. Through this direct regeneration process, high purity cathode material mixture (LiFePO4 + acetylene black), anode material mixture (graphite + acetylene black) and other by-products (shell, Al foil, Cu foil and electrolyte solvent, etc.) are recycled from scrapped LiFePO4 batteries with high yield. Subsequently, recycled cathode material mixture without acid leaching is further directly regenerated with Li2CO3. Direct regeneration procedure of recycled cathode material mixture from 600 to 800 °C is investigated in detail. Cathode material mixture regenerated at 650 °C display excellent physical, chemical and electrochemical performances, which meet the reuse requirement for middle-end Li-ion batteries. The results indicate the green direct regeneration process with low-cost and high added-value is feasible.

Extensive use of LiFePO4 batteries will afford a lot of spent LiFePO4 batteries, which cannot be recycled properly by using traditional processes at present. If these spent LiFePO4 batteries are thrown away without recycling properly, it is not only a severe waste of valuable resources, but also leads to serious environmental pollution. In this paper, a completely green recycling process and a small scale model line are developed to recycle cathode powders from spent LiFePO4 batteries for the first time. Parts of LiFePO4 host particles in spent LiFePO4 batteries decompose to FePO4, Fe2O3, P2O5 and Li3PO4 after numerous charge–discharge cycles, resulting in poor electrochemical performance of freshly recycled cathode powders for Li-ion batteries. To repair decomposed LiFePO4 host particles, recycled cathode powders are heat-treated at different temperatures. After heat-treatment at high temperatures, especially at 650 °C, cathode powders are effectively recycled and can be reused for Li-ion batteries.

To recycle valuable resource and reduce environmental pollution, a green full-solid route is designed to resynthesize LiFePO4/C materials from spent lithium-ion batteries for the first time. With this full-solid route, a simple thermal treatment process is employed to purify and homogenize the recycled cathode materials. No waste acid or alkaline liquid is used, which can avoid the secondary environment pollution. Further, the effect of Li2CO3 content on the performances of regenerated LiFePO4/C materials is investigated in detail and LiFePO4/C materials with high purity and high tap density are resynthesized. Among these resynthesized LiFePO4/C materials, the one with Li2CO3 addition amount of 1.4 wt% displays excellent physical, chemical and electrochemical performances in half cell and full cell, meeting the reuse requirement for Li-ion batteries. These results indicate that this green full-solid route with simple-operation, easily large-scale preparation, low-cost and high added-value is a feasible and promising way to recycle scrapped cathodes and reuse them.

According to the tetrahedral phase diagram of LiNiO2–LiCoO2–LiMnO2–Li2MnO3, a series of Li1.2(Ni0.2Mn0.6)x(Co0.4Mn0.4)y(Ni0.4Mn0.4)1−x−yO2 (0 ≤ x + y ≤ 1) have been designed to explore new Li-rich solid solution cathode materials. The effects of Li1.2Ni0.2Mn0.6O2, Li1.2Co0.4Mn0.4O2 and Li1.2Ni0.4Mn0.4O2 content in solid solutions on structure and electrochemical properties are investigated. Micro-sized spherical or ellipsoidal precursors are first prepared via a carbonate co-precipitation route. After calcination with lithium sources, all samples are indexed to a typical layered structure with an Rm space group as detected by X-ray diffraction (XRD). It is found that the introduction of Co can improve the tap density. However, these Co referred samples reveal lower discharge specific capacities and inferior cycle life. For these Co-free materials with high Ni content, for instance Li1.2Ni0.3Mn0.5O2, although low capacity is observed in the initial cycle, a large capacity of above 250 mA h g−1 is achieved after about 10 cycles. Importantly, the activated Li1.2Ni0.3Mn0.5O2 material still delivers a high capacity of over 230 mA h g−1 after 70 cycles, displaying superior cycle stability. These results may be instructive in designing and exploring high performance cathode materials for advanced LIBs.

A new Li-rich positive-electrode Li1.13(Ni0.26Co0.09Mn0.52)O2 is successfully achieved via a dual ammonia and oxalate chelating agent co-precipitation route for the first time, which delivers a high volumetric energy density of over 2100 W h L−1, superior cycle life and stable high median-voltage. The dual or multiple chelating agent method gives a new insight towards high energy density for Li-rich materials with outstanding electrochemical performances for advanced lithium-ion batteries.

A green recycling process was designed and used to recycle spent LiCoO2 batteries, and the recycled LiCoO2 was regenerated after the solid state synthesis with Li2CO3. XRD results showed that the layered structure of LiCoO2 was repaired after regeneration. The physical and chemical properties (XRD, morphology, tap density, average particle size, specific surface areas and pH value) and electrochemical properties (discharge capacity, attenuation rate of capacity, plateau retention at 3.6 V and attenuation rate of plateau) of LiCoO2 after regeneration were tested in detail and compared with commercial LiCoO2. The test data show that the regenerated LiCoO2 at 900 °C can meet the commercial requirements for reuse.

Monodisperse Li-deficient Li(0.35)Ni(0.2)Co(0.1)Mn(0.7)O(2-x) spinel single crystals have been prepared for the first time. The Li-deficient oxide surprisingly delivers large reversible capacity (251.3 mA h g(-1)), outstanding cycle life and low median-voltage of 2.7 V in the range of 2.0-4.9 V. Importantly, high median-voltage (4.4 V) and superior rate capability are also obtained from 3.0 to 5.0 V. These results indicate that high-energy or high-power density can be achieved by controlling discharge cut-off voltage.