Targeted regeneration and upcycling of spent graphite by defect‐driven tin nucleation

The recycling of spent batteries has become increasingly important owing to their wide applications,abundant raw material supply,and sustainable development.Compared with the degraded cathode,spent anode graphite often has a relatively intact structure with few defects after long cycling.Yet,most spent graphite is simply burned or discarded due to its limited value and inferior performance on using conventional recycling methods that are complex,have low efficiency,and fail in performance restoration.Herein,we propose a fast,efficient,and“intelligent”strategy to regenerate and upcycle spent graphite based on defect‐driven targeted remediation.Using Sn as a nanoscale healant,we used rapid heating(~50 ms)to enable dynamic Sn droplets to automatically nucleate around the surface defects on the graphite upon cooling owing to strong binding to the defects(~5.84 eV/atom),thus simultaneously achieving Sn dispersion and graphite remediation.As a result,the regenerated graphite showed enhanced capacity and cycle stability(458.9 mAh g^(−1) at 0.2 A g^(−1) after 100 cycles),superior to those of commercial graphite.Benefiting from the self‐adaption of Sn dispersion,spent graphite with different degrees of defects can be regenerated to similar structures and performance.EverBatt analysis indicates that targeted regeneration and upcycling have significantly lower energy consumption(~99%reduction)and near‐zero CO_(2) emission,and yield much higher profit than hydrometallurgy,which opens a new avenue for direct upcycling of spend graphite in an efficient,green,and profitable manner for sustainable battery manufacture.

Spent graphite regeneration:Exploring diverse repairing manners with impurities-catalyzing effect towards high performance and low energy consumption

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 300loops 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℃,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.

Preparation of lithium-ion battery anode materials from graphitized spent carbon cathode derived from aluminum electrolysis

Graphitized spent carbon cathode(SCC)is a hazardous solid waste generated in the aluminum electrolysis process.In this study,a flotation-acid leaching process is proposed for the purification of graphitized SCC,and the use of the purified SCC as an anode material for lithium-ion batteries is explored.The flotation and acid leaching processes were separately optimized through one-way experiments.The maximum SCC carbon content(93wt%)was achieved at a 90%proportion of−200-mesh flotation particle size,a slurry concentration of 10wt%,a rotation speed of 1600 r/min,and an inflatable capacity of 0.2 m^(3)/h(referred to as FSCC).In the subsequent acid leaching process,the SCC carbon content reached 99.58wt%at a leaching concentration of 5 mol/L,a leaching time of 100 min,a leaching temperature of 85°C,and an HCl/FSCC volume ratio of 5:1.The purified graphitized SCC(referred to as FSCC-CL)was utilized as an anode material,and it exhibited an initial capacity of 348.2 mAh/g at 0.1 C and a reversible capacity of 347.8 mAh/g after 100 cycles.Moreover,compared with commercial graphite,FSCC-CL exhibited better reversibility and cycle stability.Thus,purified SCC is an important candidate for anode material,and the flotation-acid leaching purification method is suitable for the resourceful recycling of SCC.

Regeneration and reuse of anode graphite from spent lithium-ion batteries with low greenhouse gas (GHG) emissions

Regenerating spent graphite(SG)from retired lithium-ion batteries(LIBs)can effectively avoid resource waste.However,the technology is challenged by the impurity content and energy consumption.In this study,micro-expanded graphite(MEG)was synthesized by one-step oxidation method using waste LIBs anode graphite as material and perchloric acid as intercalation and oxidant agent.Then,its performance as a LIBs anode material were investigated as well as the greenhouse gas(GHG)emissions of the whole process were calculated.Perchloric acid was successfully embedded in the SG during the reaction,which effectively removed the impurities in the graphite.Defects introduced during intercalation and delamination,such as nanopores and intercrystalline cracks.Both provide additional space for Li ions during charging and discharging,thereby promoting capacity enhancement.The prepared MEG expresses a rate capability as high as 340.32 m Ah/g at a current density of 0.1 C and still retains 81.73%of the capacity after 100 cycles at a current density of 1 C.Additionally,the GHG emissions of the synthesis process of this article and other literatures are compared.The results demonstrated that perchloric acid treatment process provides a low-carbon,time-and energy-saving approach for regenerated SG as battery grade material.

Preparing graphene from anode graphite of spent lithium-ion batteries

With extensive use of lithium ion batteries （LIBs）, amounts of LIBs were discarded, giving rise to growth of resources demand and environmental risk. In view of wide usage of natural graphite and the high content （12%-21%） of anode graphite in spent LIBs, recycling anode graphite from spent LIBs cannot only alleviate the shortage of natural graphite, but also promote the sustainable development of related industries. After calcined at 600°Cfor 1 h to remove organic substances, anode graphite was used to prepare graphene by oxidation-reduction method. Effect of pH and N2H4·H2O amount on reduction of graphite oxide were probed. Structure of graphite, graphite oxide and graphene were characterized by XRD, Raman and FTIR. Graphite oxide could be completely reduced to graphene at pH 11 and 0.25 mL N2H4·H2O. Due to the presence of some oxygen-containing groups and structure defects in anode graphite, concentrated H2SO4 and KMnO4 consumptions were 40% and around 28.6% less than graphene preparation from natural graphite, respectively.