The electrification of transportation and the transition of society towards low or net-zero carbon emissions has led to a skyrocketing global demand for Li-ion batteries. After a service life of three to ten years, Li-ion batteries have less than 80 % of their initial capacities and draw near to the end of their lives for practical utilization. Due to potential supply chain shortages and the value embodied in Li-ion batteries, it is imperative to recycle them, to recover the materials, and to improve the circularity and the sustinability of the industry. How to cost-effectively purify spent batteries while reducing time, energy, and waste emissions is a challenge faced by Li-ion battery recyclers. The first electrochemical membrane reactor reported in our group hasa high selectivity towards lower Cu2+, Al3+ and Fe3+ ions (<5 ppm) and retains > 95 % of the Ni2+, Co2+ and Mn2+ ions in the leachate. An advanced electrochemical membrane reactor was developed in this study. Not only does the new reactor have the same selectivity as the original reactor, but other advantages including a faster leachate processing rate (up to 10X faster). The advanced reactor can also directly generate acid at the anode side; eliminating the reactor restoration step. The prominent advantages that this electrodialysis technology has over chemical-precipitation methods include: (1) ion recovery efficiencies do not diminish after removing the impurities, Ni2+, Co2+ and Mn2+, even at a higher initial Ni2+ ion concentrations; in comparison, chemical precipitation has Ni2+, Co2+ and Mn2+ ion recovery efficiencies reduced significantly when the initial Ni2+, Co2+ and Mn2+ ion concentrations increase. (2) electrodialysis does not change the concentrations of Ni2+, Co2+ and Mn2+ ions significantly, but chemical precipitation could reduce Ni2+ and Co2+ ions to less than half of their initial values. Through electro-dialyzing the leachate, the H2 evolution reaction mechanism was found to switch from the Volmer-acid Heyrovsky mechanism to the Volmer-alkaline Heyrovsky mechanism at a pH of around 3.7.

A tremendous commitment of resources is needed to acquire, understand and apply battery data in terms of performance and aging behavior. There are many state of performance (SOP) and state of health (SOH) metrics that are useful to guide alignment of batteries to end-use, yet how these metrics are measured or extracted can make the difference between usable, valuable datasets versus data that lacks the necessary integrity to meet baseline confidence levels for SOP/SOH quantification. This work will speak to 1) types of data that support SOP and SOH evaluations on mechanistic terms, 2) measurement conditions needed to assure high data integrity, 3) equipment limitations that can compromise data high fidelity, and 4) the impact of cell polarization on data quality. A common goal in battery research and field use is to work from a data platform that supports economical paths of data capture while minimizing down-time for battery diagnostics. An ideal situation would be to utilize data obtained during normal daily use (“pulses or cycles of convenience”) without stopping the daily duty cycles to perform dedicated SOP/SOH diagnostic routines. However, difficulties arise in trying to make use of daily duty cycle data (denoted as cycle-by-cycle, CBC) that underscores the need for standardization of conditions: temperature and duty cycles can vary over the course of a day and throughout a week, month and year; polarization can develop within an immediate cycle and throughout successive cycles as a hysteresis. If CBC data is envisioned as a data source to determine performance and aging trends, it should be recognized that polarization is a frequent consequence of CBC and thus makes it difficult to separate reversible and irreversible components to metrics such as capacity loss and resistance increase over aging. Since CBC conditions can have a major impact on data usability, we will devote part of this paper to CBC data conditioning and management. Differential analyses will also be discussed as a means to detect changing trends in data quality. Our target cell chemistries will be lithium-ion types NMC/graphite and LMO/LTO.

The expanding electric vehicle market brings with it exponential growth in the use of lithium (Li)-ion batteries (LIB) for which a wave of spent LIB is expected to come within the next 5 to 10 years. Due to the economic and strategic value imbedded within the metals contained in LIB, different recycling technologies, including hydrometallurgy, pyrometallurgy and direct recycling, are under development. Being different from previous hydrometallurgical methods, which may have high chemical consumption and negative environmental impact, an electrochemical membrane reactor is designed and validated for the first time, to electrify and decarbonize the impurity removal process. This reactor electroplates copper (Cu) and electrochemically precipitates aluminum (Al) and iron (Fe) from simulated spent LIB leachates, by consuming only air, water, and electricity, and the impurities are reduced to <1 ppm. The purified leachate maintains 99.5 % of the nickel (Ni), 95.4 % of the cobalt (Co) and 99.14 % of manganese (Mn) from the original leachate solution, and then can be directly applied for cathode precursor synthesis. Additionally, the purification process doesn't introduce extra impurity, and the reactor restoration process generates valuable by-product hydro sulfate (H2SO4). This electrochemical process can reduce the cost, because of the much less chemical consumption and the valuable by-product generation, and mitigates the waste emissions, because of no extra impurity introduced and no greenhouse gas (GHG) produced. The chemical precipitation method uses significant amount of NaOH, which induced GHG emission during the manufacturing process.

A key step limiting how fast batteries can be deployed is the time necessary to provide evaluation and validation of performance. Using data analysis approaches, such as machine learning, the validation process can be accelerated. However, questions on the validity of projecting models trained on limited data or simple cycling profiles, such as constant current cycling, to real-world scenarios with complex loads remains. Here, we present the ability to predict performance with less than 1.2 % mean absolute percent error when trained on cells aged using complex electric vehicle discharge profiles, and either AC Level 2 charge or DC Fast charge profiles, using only the first 45 cycles, namely 5 % of the total testing time. While error is low across the projections, this study also highlights that battery lifetime analysis using only cycling data may not extrapolate safely to certain real-world conditions due to the impact of calendar degradation.

Surface impurities involving parasitic reactions and gas evolution contribute to the degradation of high Ni content LiNixMnyCozO2 (NMC) cathode materials. The transient kinetic technique of temporal analysis of products (TAP), density functional theory, and infrared spectroscopy have been used to study the formation of surface impurities on varying nickel content NMC materials (NMC811, NMC622, NMC532, NMC433, NMC111) in the presence of CO2 and H2O. CO2 reactivity on a clean surface as characterized by CO2 conversion rate in the TAP reactor follows the order: NMC811 > NMC622 > NMC532 > NMC433 > NMC111. The capacity of CO2 uptake follows a different order: NMC532 > NMC433 > NMC622 > NMC811 > NMC111. Moisture pretreatment slows down the direct CO2 adsorption process and creates additional active sites for CO2 adsorption. Electronic structure calculations predict that the (012) surface is more reactive than the (1014) surface for CO2 and H2O adsorption. CO2 adsorption leading to carbonate formation is exothermic with formation of ion pairs. The average CO2 binding energies on the different materials follow the CO2 reactivity order. Water hydroxylates the (012) surface and surface OH groups favor bicarbonate formation. Water creates more active sites for CO2 adsorption on the (1014) surface due to hydrogen bonding. The composition of surface impurities formed in ambient air exposure is dependent on water concentration and the percentage of different crystal planes. Different surface reactivities suggest that battery performance degradation due to surface impurities can be mitigated by precise control of the dominant surfaces in NMC materials.

With the widely equipped Lithium-ion batteries (LIBs) in electronics and electric vehicles, proper handle spent LIBs has been the subject of increasing concern. Significantly raised concerns about resource constraints and environmental issues are brought by spent LIBs. Therefore, properly handling spent LIBs is urgent and necessary.[1] However, until now, getting manufacturers to recruit recycled materials has been a hard sell because recycled materials are deemed as inferior to commercial materials, which limits the development of recycling. Although previous publications stated that their recovered materials had a comparable performance as commercial materials, the results, based on coin cells and low electrode loading, cannot convince manufacturers to employ recycled materials in the new LIBs.[2] Here, we demonstrate that recycled cathode materials with optimized microstructure have the best industrial relevant testing results (up to 11Ah cells) so far and compare them with state-of-the-art commercial equivalent. Interestingly, the recycled materials not only pass all the aggressive industrial plug-in hybrid electric vehicle (PHEV) battery tests, but also outperform control counterparts in some tests. Specifically, 1 Ah cells with the recycled LiNi1/3Mn1/3Co1/3O2 have the best cycle life result reported for recycled materials and enable 4,200 cycles and 11,600 cycles at 80% and 70% capacity retention, which is 33% and 53% better than the state-of-the-art, commercial LiNi1/3Mn1/3Co1/3O2. Meanwhile, its rate performance is 88.6% better than commercial powders at 5C. Through detailed experimental and modeling analysis of pristine and cycled materials, we discover that the unique porous and larger inside void microstructure enables the superior rate and cycle performance and less phase transformation. Compared with the control sample, the surface area of the recycled LiNi1/3Mn1/3Co1/3O2 is 82.14% larger and the cumulative pore volume is 61.25% larger. Even some recycled particles have an outer diameter of the void space equal to 40% to 60% of the particle diameter. The unique microstructure can reduce 16% hoop stress during the discharge/charge process compared to control materials, and improve the lithium chemical diffusion coefficient, enabling the superior performance of cycle life and rate performance and less phase transformation. The results pave the way to re-introduce recycled materials into new batteries.[3] [1] M. Chen, X. Ma, B. Chen, R. Arsenault, P. Karlson, N. Simon, Y. Wang, Recycling End-of-Life Electric Vehicle Lithium-Ion Batteries, Joule 2019, 3, 2622.10.1016/j.joule.2019.09.014 [2] X. Ma, L. Azhari, Y. Wang, Li-ion battery recycling challenges, Chem 2021.10.1016/j.chempr.2021.09.013 [3] X. Ma, M. Chen, Z. Zheng, D. Bullen, J. Wang, C. Harrison, E. Gratz, Y. Lin, Z. Yang, Y. Zhang, F. Wang, D. Robertson, S.-B. Son, I. Bloom, J. Wen, M. Ge, X. Xiao, W.-K. Lee, M. Tang, Q. Wang, J. Fu, Y. Zhang, B. C. Sousa, R. Arsenault, P. Karlson, N. Simon, Y. Wang, Recycled cathode materials enabled superior performance for lithium-ion batteries, Joule 2021.10.1016/j.joule.2021.09.005

A safe and reliable battery operation needs effective diagnostic tools. A quantitative failure analysis (FA) to enable cell qualification and quantify its effectiveness for reliable and safe operation of rechargeable Li batteries (RLB) is shown here. The method can identify and quantify potential failure based on the state of charge (SOC) under any operating conditions. A precise and accurate electrochemical analytic diagnosis (eCAD) of 14 rechargeable Li || NMC-622 cells of the same build are used as an example. The FA by eCAD can quantitatively decipher good, bad and ugly cells in cycle aging. The cell qualification is based on thermodynamic SOC, not experimental conditions. The method provides a quantitative failure mode and effect analysis to reveal diverse ‘dead Li’ formation that affects the reversibility of the Li anode and charge retention in the cell. This cell qualification method highlights the potential to improve cell quality for safe operation, with strong implications for early fault detection, FA, risk mitigation, state estimation and life prediction for reliable and safe RLB operations.

Rechargeable lithium battery (RLB) technology is transforming portable devices, vehicle electrification, and grid modernization. To make RLB durable, reliable and safe, conducting failure mode and effect analysis (FMEA) to identify failure mechanism under the operating conditions is very desirable. However, this ability is often overlooked or even lacking. The failure analysis (FA) is often conducted by laboratory testing and postmortem analysis, and the knowledge typically empirical. Here we present a quantitative approach for FMEA that can reveal how failure modes and effects reduce the capacity of a RLB. This approach is based on the state of the battery for FMEA, contrary to the conventional approach based on operating or testing conditions. The key aspect of this FMEA method is to convert the experimental results to a state-of-charge (SOC)-based analytic methodology. Such a conversion can separate the thermodynamic and kinetic attributes of capacity fade based on compositional correspondence in the electrode, so the loss and the decreased utilization of the active materials can be determined respectively.

Even though electroplating has been applied to extract antimony from the relevant mines, such as stibnite (Sb2S3) and valentinite (Sb2O3), there are still some unclear points which need to be clarified: in alkaline sulfide solution, S2− can help increase the solubility of Sb(III) ions. In the present study, cyclic voltammetry (CV) and chronoamperometry (CA) tests were employed to investigate the electrochemical behavior of antimony ions in KOH solution (20 wt%), and the results revealed that Sb(III) ions have much higher electrochemical activity than Sb(V) ions. However, Sb(V) ions are not completely inactive at the potential before H2 evolution reaction, as previous studies reported, and part of Sb(V) ions can be electroplated in the KOH solution. The contradictions between the present and previous studies are due to the impurity caused by Sb(III) ions, which are speculated to play a role in Sb(V) ion reduction. Ions such as As3+, Si4+, CO32−, Al3+, and Sn2+ show no interference on the electroplating of antimony. Other electrochemical and chemical behaviors are clarified in this study as well: (1) the Sb(III)/Sb(0) couple is more electrochemically reversible at the interface of antimony metal/KOH solution than that at the interface of a glass carbon/KOH solution; (2) in a sulfide alkaline solution system, S2− ions can coordinate with Sb(III) ions and lower the reduction potential of Sb(III) ions to antimony metal, thus leading to a lower current efficiency of antimony electroplating. The reducing reagents, including KI, K2SO3, and KBH4, can reduce Sb(V) ions to Sb(III) ions in an acid solution, but these chemical reduction reactions cannot happen in the KOH solution. These fundamental studies can provide knowledge on antimony refining from the relevant secondary resources.

The lithium-ion battery (LIB) recycling market is becoming increasingly important because of the widespread use of LIBs in every aspect of our lives. Mobile devices and electric cars represent the largest application areas for LIBs. Vigorous innovation in these sectors is spurring continuous deployment of LIB powered devices, and consequently more and more LIBs will become waste as they approach end of life. Considering the significant economic and environmental impacts, recycling is not only necessary, but also urgent. The WPI group has successfully developed a closed-loop recycling process, and has previously demonstrated it on a relatively small scale 1 kg spent batteries per experiment. Here, we show that the closed-loop recycling process can be successfully scaled up to 30 kg of spent LIBs from electric vehicle recycling streams, and the recovered cathode powder shows similar (or better) performance to equivalent commercial powder when evaluated in both coin cells and single layer pouch cells. All of these results demonstrate the closed-loop recycling process has great adaptability and can be further developed into industrial scale.

Metal oxides are used as the energy materials in some aqueous and nonaqueous batteries. However, a large overpotential and poor rate-performance limit their wide application. Low electrical conductivity of the oxide is commonly considered to be the reason for these limitations. The present study specifically reveals the electrochemical reduction process of α-Fe2O3 particles by using a cyclic voltammetry technique combined with an electron spectroscopy technique. SEM and TEM observe the phase and crystal structure transformation process during α-Fe2O3 reduction at the nanoscale, and EDS analyzes the composition change of particles at various periods. The surface of α-Fe2O3 particles is reduced to an amorphous compound first, and then O2- ions diffuse from the crystal matrix toward the outside simultaneously causing defects inside the particles. Experiments prove that γ-Fe2O3, Fe3O4, CuO, and Bi2O3 have the same rate-limiting step as α-Fe2O3; that is, O2- ions diffuse inside the oxide particles toward the outside. The diffusion coefficients of O2- in these metal oxides are also estimated. This study demonstrates that the ionic conductivity of metal oxides is the critical factor which affects the overpotential and rate-performance of the batteries with these oxides as active material, and the O2- ion diffusion coefficient must be considered when selecting or designing metal oxides as energy material. The conclusion that O2- diffusion in oxides is the rate-limiting step of their reduction may be applicable to a group of oxides whose reduction reaction is not involved in ion diffusion from an electrolyte into their crystal matrix.

For environmental and sustainability reasons, spent Li-ion batteries must be recovered and recycled so that the full promise of an electrified future is realized. Li-ion battery recycling streams pose a serious challenge to all existing recycling technologies because of their unknown and diverse chemistry. In the work described in this paper, four representative recycling streams were used to demonstrate the flexibility of the recycling process developed at Worcester Polytechnic Institute (WPI) to accommodate a variable feed and to generate consistent quality cathode material, LiNi1/3Mn1/3Co1/3O2 (NMC111). Ni1/3Mn1/3CO1/3(OH)2 precursors derived from four recycling streams were produced by a hydroxide coprecipitation method in a continuous stirred tank reactor. It took 2 days for the coprecipitation reaction to reach steady state. A possible evolution of the precursor particles up to the steady state was proposed. Both the precursors and the cathodes from these four different recycling streams exhibit sim...

Whether CuO reduction is one step or two steps reaction has been argued for several decades, and one step reaction mechanism is mainly supported by CuO CV (cyclic voltammetry) profile, where only one cathodic peak represents the direct reduction from CuO to Cu. However, some researchers support two steps reaction mechanism, because they observed Cu2O as intermediate with spectroscopy technique or two cathodic peaks in the CV profile. In this study, two colloid electrodes containing crystal CuO particles are electrolyzed in KCl electrolyte at -1.7 V and -1.65 V respectively, and both of the products are composed of Cu2O and Cu. The electrolysis voltage can change the weight ratio of Cu2O and Cu, and the electrolysis results firmly prove that CuO reduction is two steps reaction: CuO is reduced to Cu2O, then to Cu. Therefore, the rationality of the criterion for determining one step reaction is re-considered in this study. The experimental conditions and parameters, including CV scan rate, atom arrangement of CuO, particle size of CuO, and anions and pH value of electrolyte, are discussed in the present study, and all these factors can affect CuO reduction process, thus influencing the cathotic peaks, such as the number, shape and potential of the peaks in CuO CV profile. It could lead to incorrect conclusion, when CuO reduction steps is determined by the cathode peak without comprehensive consideration of the effect from all these factors. In another word, cathodic peak number in the CV profile sometimes is not a straightforward and appropriate criterion to determine the number of steps of CuO reduction. In addition, S2- ions is found to be an effective addtive to enhance the cyclic ability and discharge plateau of Cu alkaline battery in this study. (C) 2018 The Electrochemical Society.

The electro-reduction of magnetite is important for many different industries. For example, it relates to the extraction of iron from iron ore and the charging of iron-based batteries. The sluggish electro-reduction reaction of magnetite affects the energy efficiency of iron extraction or the charge rate of iron-based batteries. However, what factors affecting the reduction rate is not well understood. In this study, electrochemical analysis, XRD, SEM, EDS mapping and XPS techniques are adopted to analyze the reaction, and it is proved that two factors determine the electro-reduction rate of magnetite electrode: O2− diffusion inside the particles determines the electro-reduction rate of a single particle, and the electrical resistivity of electrode determines how many magnetite particles are involved in electro-reduction simultaneously. Contact resistance between particles is the dominant part of the electrical resistance of the magnetite electrode. The function mechanism of sulfide in the reaction is also revealed: a sulfide additive can react with magnetite to form amorphous or crystal FeS at different potentials. These compounds, especially crystal FeS, coat onto the surface of magnetite particles, and bond them together. The coating and bonding can decrease contact resistance significantly, thus enhancing the electro-reduction rate of magnetite to one order of magnitude.

Electrochemical reaction process of iron oxide reduction has been investigated for several decades, and both solid-state reaction mechanism and dissolution/re-deposition mechanism were proposed for the reduction process. The previous studies observed the reaction process from macro-and micro-scale, and how the intermediate participates in the dissolution/re-deposition route is unclear. In this study, a mixture of Fe2O3 nano-particles and carbon powder was electrolyzed in an alkaline solution, and the morphology of the product depended on the electrolysis temperature. The Fe2O3 nano-particle aggregates can be electrolyzed into micro-size hollow partciles at 60 degrees C. To explain this phenomenon, ex-situ SEM technique combining with TEM was adopted to observe the morphology change of Fe2O3 particles on the surface of the glass carbon electrode at nano-scale at a series of electrode potentials. The surface of the particle was reduced to amorphous compounds firstly, and these compound was the intermediate participating in dissolution/re-deposition process to form new crystals. The solubility of these amorphous compound is relative low at 60 degrees C, and the compouds stayed in their original position, connected and stabilized each other to form micro-size iron shell. They can dissolve into eletrolyte, migrate to somewhere, and re-deposit to construct new crystals at higher temperature. This study not only presents an innovative and efficient way to electrolyze micro-size hollow iron particles, but also provides some new discovery about Fe2O3 electrochemical reduction process. (c) 2017 The Electrochemical Society. All rights reserved.

Iron-based alkaline batteries are extremely attractive due to iron's environmental friendliness, and low cost. The parasitic reaction of H2 evolution and the poor electrical conductivity of the discharge products are among the major barriers for the commercialization of these batteries. In this paper, we first show that O(2-) diffusion inside the solid Fe2O3 particles is the rate-limiting step in the reduction reaction. In situ sulfide modified Fe2O3, which has a core-shell structure verified by SEM, XRD and XPS analysis, has excellent electrical and ionic conductivity. The functional mechanism of sulfide in the reaction was identified as in the potential region around -1.071 V (vs Hg/HgO), the outside layer of Fe2O3 was reduced to amorphous FeS, which has good electrical conductivity and enlarges the electrochemical reaction interface. O(2-) diffusion inside the Fe2O3 particle is still the rate-limiting step. In the potential region around -1.15 V (vs Hg/HgO), amorphous FeS ages to FeS (pyrrhotite), FeS2 (marcasite), and FeS0.9 (mackinawite), which have high electrical conductivity. FeS0.9 can also introduce vacancies into Fe2O3 particles, which can greatly enhance O(2-) diffusion and the ionic conductivity, and the surface reaction is the rate-limiting step. In summary, after in situ sulfide modification, the ohmic overpotential and ion diffusion overpotential for Fe2O3 reduction were significantly reduced. The reduction reaction rate increases 26 times and the discharge capacity of Fe2O3 electrode increases 78 times after sulfide modification.

The lithium ion (Li-ion) battery industry has been growing exponentially since its initial inception in the late 20th century. As battery materials evolve, the applications for Li-ion batteries have become even more diverse. To date, the main source of Li-ion battery use varies from consumer portable electronics to electric/hybrid electric vehicles. However, even with the continued rise of Li-ion battery development and commercialization, the recycling industry is lagging; approximately 95% of Li-ion batteries are landfilled instead of recycled upon reaching end of life. Industrialized recycling processes are limited and only capable of recovering secondary raw materials, not suitable for direct reuse in new batteries. Most technologies are also reliant on high concentrations of cobalt to be profitable, and intense battery sortation is necessary prior to processing. For this reason, it is critical that a new recycling process be commercialized that is capable of recovering more valuable materials at a higher efficiency. A new technology has been developed by the researchers at Worcester Polytechnic Institute which is capable of recovering LiNi (x) Mn (y) Co (z) O-2 cathode material from a hydrometallurgical process, making the recycling system as a whole more economically viable. By implementing a flexible recycling system that is closed-loop, recycling of Li-ion batteries will become more prevalent saving millions of pounds of batteries from entering the waste stream each year.

In the process of low temperature electrolysis of Fe2O3, an electrical-ionic conductive colloidal electrode containing the electrochemically active species, the liquid electrolyte and a percolating electrical conductor has been successfully fabricated and used to produce Fe.