Li-Fe anti-site defects, as an inherent defect in the crystal structures of LiFePO4, are inevitably introduced during synthesis and battery cycling. Traditionally, it was seen as a barrier to Li ions diffusion, but it was proved that Li-Fe anti-site defects can enhance anisotropic diffusion and optimize energy storage through new diffusion channels, which was related to a synergistic effect with tensile stress traits. However, the detailed mechanism among Li-Fe anti-site defects and electrochemical performance remains complex, potentially involving other properties, such as magnetism performance. Series of effective characterization technologies, including FITR, XRD Rietveld refinement, and STEM, offer diverse methods to analyze these defects, each with unique merits. Tailoring the concentration of Li-Fe anti-site defects is crucial for improving the electrochemical properties of LiFePO4, and strategies such as ion doping, synthesis control, and structure engineering are essential. These insights are valuable for the commercial production and recycling of LiFePO4. Despite progress, the impacts of Li-Fe anti-site defects on energy storage remain debated, underlining the need for further research into their relationships with material properties. Optimizing the synthesis and recycling processes by controlling Li-Fe anti-site defects promises a more efficient and sustainable energy storage system construction.

Fascinated by the high value and low pollution, the direct recycling of spent LiNi0.5Co0.2Mn0.3O2 (S-NCM) has triggered plenty of exploring activities. Considering different industry sources, they always display various particle sizes and surface traits. Therefore, the simple recovery of chemical defects hardly meets the market demand. Herein, the homogenized strategy, containing physical crushing and chemical recovering, is introduced to regenerate morphology and components of S-NCM, where the successfully regenerated samples displayed uniform particle size and stable chemical lattice. Assisted by physical crushing, the precursors show a large contacting area with oxygen during morphology reconstruction, accompanied by the effective repairing of the internal lattice. More significantly, the unique manner induces the repairing of oxygen vacancies (OVs) and the lowering of Li/Ni disorder, bringing about enhanced structural stability. Moreover, the lowering of oxygen redox activity and the improvement of oxygen binding energy are further revealed by theoretical calculations. The as-optimized regenerated samples display a considerable capacity of 139.6 mAh g-1 with a remarkable capacity retention of 94% at 1.0 C. Even at 5.0 C, its capacity retention could be kept at approximate to 80.8% after 150 loops. Given this, this work is expected to provide effective guidance for different NCM regenerations, meanwhile offering an in-depth understanding of morphology/lattice reconstruction.

Based on its high economic/sustainability value, the upcycling of spent cathodes into anodes has been deemed to be an alternative strategy to traditional chemical synthesis. Supported by an effective acid leaching and coordination-trapping self-assembly reaction, a nano-scale CoS@NSC anode was successfully prepared from spent LiCoO2 and used as a promising anode for lithium ion batteries.

Direct regeneration, as the main recycling manner, displays the short-process and high economic value, which has been devoted to considerable attentions. Limited by the existed pre-treatments, there are still some Al-impurities of spent material, resulting in the unstable electrochemical properties of regenerated material, meanwhile the excessive removal of Al-impurities brings the risk of regeneration cost. Thus, exploring the threshold reference of Al-impurities is urgent for regeneration of spent materials. Herein, through the introduction of Al2O3 with different content, spent LiCoO2 were successfully regenerated, displaying the evolution of physical-chemical properties. With suitable Al adding (0.02 wt.%), the broadening layer distance and storage space are found. As a cathode, the as-optimized sample shows a capacity of 172.7 mAh g−1 at 0.2 C, and the capacity retention was 84% after 500 cycles at 5.0 C, even better than Al-impurity-free regenerated sample. Supported by the detailed kinetic analysis, it could be deduced that, suitable Al-introduction is beneficial for the fast insertion/extraction of ions, meanwhile too excess adding could bring about the blocking of diffusion paths and by-production surface stacking. Given this, this work is expected to shed light on the physical-chemical effect of Al-impurities, meanwhile offering the threshold reference for Al-doping content in practical regenerated industry.

Direct regeneration of LiFePO4 (LFP), as a promising short-process recycling method, has attracted considerable attention. However, spent materials in industry mainly arise from large-scale mechanical dismantling, which is composed of spent graphite, whereas retired graphite constitutes 30% of mixed materials. Owing to the high oxidation temperature of graphite, a relatively high sintering temperature is selected for graphite removal. However, over-calcined LFP pre-oxidized precursors lead to low recovery of the spent phase. Herein, a purification-lithiation collaborative regeneration method is proposed for preparing precursors with high purity. Assisted by a "tailored" reductive carbon, the crystalline phase was recovered. As a Li-storage cathode, the optimized samples displayed an initial capacity of 133.0 mA h g(-1) at 1.0C. Even at a current density of 5.0C, optimized samples showed 112.5 mA h g(-1) with 100% capacity retention ratio after 500 cycles. Supported by detailed physical-chemical analysis, the rationally introduced Li-Fe anti-sites could induce the construction of two-dimensional Li-diffusion channels, along with enhanced Li-diffusion behaviors. This work is expected to provide guidance of the direct regeneration process of LFP samples with graphite impurities.

As great potential recycling strategy, the direct regeneration of spent LiCoO2 (LCO) is beneficial for lowering environmental pollutions and promoting global sustainability. However, owing to the using of binder and electrolyte, some fluorine impurities would be remained into spent materials. Considering the doping behaviors of F-elements, their suitable content introducing would facilitate the energy-storage abilities of regenerated LCO. Herein, through the tailored introduction of F-elements, spent LCO are successfully regenerated with physical-chemical evolutions. Benefitting from the existed oxygen vacancies, the diffusion energy-barrier of F-elements is reduced from 1.73eV to 0.61eV, facilitating the establishment of gradient F-doped subsurface, along with the formation of rigid CoO5F. Meanwhile, excess F-elements (1wt%, as a threshold) lead to the formation of LiF passivation layer on the surface. Thus, the as-optimized sample displays a considerable capacity of 154.4mAhg(-1) even at 5.0C, with retention rate (88.3%) in 3.0-4.5V. Supported by detailed electrochemical and kinetic analysis, the structural advantages are confirmed to boost the improved redox activity of Co-ions and the alleviating of irreversible oxygen-release. Give this, the work is anticipated to reveal the evolutions of regenerated LCO with the introduced F-elements, whilst providing the practical regeneration strategies toward excellent high-voltage properties.

Attracted by the potential value of spent lithium-ion batteries, their high effective-recycling has been devoted to numerous attentions. Unfortunately, spent graphite is always used as fossil fuel, accompanying with the serious resources wasting and carbon emission. Owing to low-cost and energy-consumption, their direct regeneration has been regarded as the next-generation key technology. Although high-temperature sintering can induce the recovering of internal structure, they still suffer from strong surface anisotropy. Herein, through the introduction of coating-layer, their infiltration abilities and isotropy are effectively improved. And, their physical-chemical properties can be recovered to that of commercial materials, containing compact-density, impurities-content and conductivities. The as-regenerated sample delivers a Li-storage capacity of 324 mA h g- 1 at 1.0 C after 250 cycles. Even at high rates, their specific capacity can be still kept at about 286 mA h g- 1 after 300 loops. Assisted by detailed electrochemical analysis, the pre-storage role of surface/near-surface layer is successfully confirmed, accompanied by stable charge balance. Moreover, its diffusion energy barrier of layers is further decreasing, accompanying with the considerable ion-diffusion behaviors. Therefore, the work is anticipated to provide significant surface-tailoring strategy for spent graphite, meanwhile illustrating the in-depth understanding of carbon-layers effect.

Captured by relatively low energy consumption and harmful gas-emission, direct regeneration has captured numerous attention, but still suffers from different particle sizes and diverse doping hetero-elements, hardly meeting the market demand. Herein, assisted by the crush-sinter regeneration from element to grain further to particle, homogenized recovery of hetero spent LiCoO2 is successfully carried out. More interestingly, after tailoring Li/Co anti-sites ratio, the redox activity of Co-ions is remarkably enhanced, effectively inhibiting the irreversible escape of O-atoms under high voltage, bringing about the fascinating electrochemical performance and structural stability. As anticipated, the regenerated LiCoO2 delivered a considerable capacity of 175.2 mAh g(-1) at 1.0 C, whilst its capacity retention can remain at 88.86% even after 500 cycles at 5.0 C, better than that of commercial materials. Assembling regenerated materials versus. graphite pouch cell, their considerable practical capacity retention can be kept at approximate to 91.4% even after 500 cycles. Supported by in situ XRD, electronic structure analysis, and detailed DFT calculations, the excellent high voltage stability of optimized samples mainly comes from the alleviating of phase conversion and oxygen redox. This work is expected to shed light on the potential value of homogenized regenerations, and offer effective strategies of upcycling about spent LCO.

Captured by the economic value and environmental friendliness, the high-value recycling of spent batteries has been devoted plenty of attention. However, the regenerated graphite is still limited by large anisotropy and inferior rate abilities. Through the tailoring of low-temperature ionic liquid, the further regenerated graphite displayed rich sub-surface pores and improved crystalline degree, bringing about strong wettability and enhanced isotropy. Utilizing as lithium-storage anode, the optimized sample could deliver a capacity of 321 mAh/g after 300 loops at 1.0 C. Even at 2.0 C after 400 cycles, their capacity could also remain about 278 mAh/g. Supported by the detailed kinetic analysis, the abundant pores of sub-surface served significant roles in the enhancements of diffusion/surface-controlling behaviors. Their pre-storage advantages would be beneficial for the alleviation of voltage dropping, resulting in improved rate properties. Meanwhile, its activation energy was calculated at about 14.52 KJ mol−1, revealing its relatively small ion-diffusion energy barrier. More significantly, assisted by economic analysis, its revenue could also reach up to 5700$ t−1, with a promising recycling value. Given this, the work is expected to offer significant cooperative regeneration manners and shed light on the significant effect of sub-surface designing.

A chemical-physical investigation proved that the loss of active Li represents the main mechanism of capacity-fading in spent LiFePO4. Given this, functional Li2CuO2-coated separators were fabricated from spent Cu foil and found to contribute to the regeneration of spent LiFePO4 in a full-cell system. This study presents a novel method for cathode/Cu foil recovery.

Spent battery recycling has received considerable attention because of its economic and environmental potential. A large amount of retired graphite has been produced as the main electrode material, accompanied by a detailed exploration of the repair mechanism. However, they still suffer from unclear repair mechanisms and physicochemical evolution. In this study, spent graphite was repaired employing three methodologies: pickling-sintering, pyrogenic-recovery, and high-temperature sintering. Owing to the catalytic effect of the metal-based impurities and temperature control, the as-obtained samples displayed an ordered transformation, including the interlayer distance, crystalline degree, and grain size. As anodes of lithium ions batteries, the capacity of repaired samples reached up to 310 mA h g(-1) above after 300 loops at 1.0 C, similar to that of commercial graphite. Meanwhile, benefitting from the effective assembly of carbon atoms in internal structure of graphite at >1400 degrees C, their initial coulombic efficiency were >87%. Even at 2.0 C, the capacity of samples remained approximately 244 mA h g(-1) after 500 cycles. Detailed electrochemical and kinetic analyses revealed that a low temperature enhanced the isotropy, thereby enhancing the rate properties. Further, economic and environmental analyses revealed that the revenue obtained through suitable pyrogenic-recovering manners was approximately the largest value (5500 $ t(-1)). Thus, this study is expected to clarify the in-depth effect of different repair methods on the traits of graphite, while offering all-round evaluations of repaired graphite.

Developing novel anodes with outstanding fast-charging properties is crucial for next-generation energy storage research. Sb2S3 materials are deemed promising electrodes due to their high theoretical specific capacity. However, they are restricted by sluggish bulk-phase kinetics, bringing about inferior electronic conductivity at high current density. In this work, the cable-like SS@C-x anodes are successfully prepared via the thermal-chemical treatment method. Through the tailoring of habit modifiers, their unique core-shell architectures are induced with (hk1) preferential planes and the construction of S-defects, accompanied by lowered energy barriers. Meanwhile, assisted by C-S and C-O-Sb bonds, the charge accumulation on the surface can be rapidly released toward the bulk phase. As expected, for the as-optimized samples, the capacity of 603.7 mAh g(-1) can remain after 100 cycles at 1.0 A g(-1). Even at 10.0 A g(-1), their superior capacity of 436.1 mAh g(-1) can be noted, and it still displayed the reversible capacity of 479 mAh g(-1) at -5 degrees C. Assisted by kinetic analysis, the great electrochemical properties mainly come from the reduced migration energy barriers and accelerated Li+ diffusion rates. Given this, the work is expected to shed light on crystal orientation tuning and defect engineering for advanced metal-based energy storage materials.

Large-scale recycling spent LiFePO4 (LFP) has aroused the enthusiasm of widespread studies due to its significant economic/environmental values. Restricted by the accuracy of mechanical disassembling, Cu element would be inevitably introduced into the spent samples, resulting in the existence of impurities. Exploring precise thresholds of Cu-impurities was significant in commercial promotion of LiFePO4 regeneration processes. Theory calculation proved that Cu-doping was beneficial to accelerate the diffusion process of Li ions in LFP lattice. Inspired by the theory calculation, a generation process with tailored Cu-impurities content was designed in this work. Supported by the well-designed regeneration process, Cu ions can be rationally doped into the lattice of spent LFP, contributing to the attractive electrochemical properties. Utilized as the cathode of LIBs, the capacity of samples with optimized Cu-impurities content achieved about 130 mAh/g at 2.0C, accompanied by a capacity retention of 100 % among 300 cycles. Importantly, the in-depth mechanism between the reversibility and Cu-impurities threshold is investigated by in-suit XRD, especially the irreversible phase evolution of regenerated samples with excessive Cu-impurities introducing. Given this, this work revealed the in-depth mechanism between Cu-impurities threshold and electrochemical performance, while contribute to the large-scale regeneration of spent LFP.

Rechargeable sodium-selenium (Na–Se) batteries have captured extensive attention in energy-storage systems due to their attractive power density, excellent conductivity, and security. Optimizing battery components and mechanistic investigations serve as crucial roles in realizing the advancements of Na–Se batteries. Thus, the reaction mechanisms and representative research progress of Na–Se batteries have been explored in this work. An impressive array of advances in the fields of cathode materials designing, electrolyte optimization, and functional separators construction are discussed specifically. In addition, a delicate division of design routes focusing on cathode materials, including C/Se composites, metal-compounds incorporated cathodes, and catalytic electrode approaches, is provided, and their core design concepts are summarized. In the end, the challenges and future development direction of Na–Se batteries are shed light on in this review to promote their wide utilization.

Owing to its high theoretical specific capacity, effective working voltage, and abundant raw materials, antimony sulfide (Sb2S3) was regarded as one promising anode material for electrochemical energy conversion and storage, especially regarding alkali-ion (Li+, Na+, and K+) batteries. Currently, using chemical agents or minerals as precursors, numerous strategies have been utilized to prepare multiple-morphology Sb2S3 electrodes accompanied by remarkable energy-storage performances. Therefore, analyzing the traits of chemically synthesized Sb2S3 and natural stibnite-based anodes was of great importance for further exploration about this type of material. In this review, recent achievements of Sb2S3-based composites for LIBs/SIBs/PIBs were overviewed solidly from varied synthesis routes (chemical synthesis and direct preparation) and dimensional designing (low-dimensional structures and 3D structures). Also, the corresponding Li+/Na+/K+-storage mechanisms and series of modification strategies for Sb2S3 (containing impurity-removing, nanostructure-optimization, carbon-incorporating, and external metal matrix recombination) were explored in this paper. This work is expected to summarize the characteristics of Sb2S3-based anode materials for alkali-ion battery systems and further shed light on their prospects and challenges.