Lithium Transition Metal Oxides Research Articles

Water-aerosol-assisted roasting for selective lithium extraction from spent lithium-ion batteries

Selective extraction of lithium from spent lithium-ion batteries (LIBs) represents a promising solution for efficient lithium recovery. Herein, a water-aerosol-assisted roasting technology is proposed to selectively extract lithium from spent lithium transition metal oxides (LTMOs) cathodes. In an exemplary recycling of spent LiCoO2, the cathode material undergoes a low-temperature (350°C) chlorinating roast process to convert it into metal chlorides, followed by a higher-temperature (500°C) roasting to facilitate the selective pyrolysis of CoCl2. The presence of water-aerosol significantly enhances the selective pyrolysis process of CoCl2, reducing roasting time eightfold compared to conventional air roasting. Subsequent water-leaching effectively extracts 99.1 % of lithium as LiCl, while only 0.2 % of cobalt is extracted, ensuring selective lithium recovery. The resulting high-purity LiCl solution and Co3O4 residue are directly utilizable for producing battery-grade Li2CO3 and LiCoO2, respectively. Regenerated LiCoO2 demonstrates excellent cycling stability, retaining 90.5 % of its capacity after 300 cycles at 1C rate. Moreover, this method is applicable to ternary cathodes (NCM) black mass, offering a sustainable, robust, and cost-effective approach for lithium extraction from spent LIBs.

Enhanced Electrochemical Performance of Disordered Rocksalt Cathode in a Localized High Concentration Electrolyte

Lithium (Li) transition metal oxides with layered structure, commonly employed as cathodes in Li-ion batteries, exhibit limited capacity, and employ less abundant and costly materials, raising sustainability concerns amid surging battery demand. Addressing this, lithium rich cation disordered rock salt cathode (DRX) materials have garnered substantial attention as they offer high capacity and cost benefits. Manganese (Mn) based DRXs, in particular, show promise due to the utilization of earth abundant materials and good thermal stability of Mn. However, these cathodes often face challenges when cycled in state-of-the-art carbonate-based electrolytes. These include severe side reactions between the cathode and the electrolyte, transition metal dissolution and structural instability of the cathode particles all of which result in fast capacity fading. In this work, an advanced localized high concentration electrolyte (LHCE) is developed to mitigate these problems and enable stable cycling of Li1.2Mn0.6Ti0.2O2 (LMTO). The developed LHCE exhibits high voltage stability, forming an ultrathin and stable electrode/electrolyte interphase. Consequently, Li||LMTO half cells with the developed LHCE demonstrate increased capacity, enhanced cycling stability and superior rate capabilities compared to the cells with the conventional electrolyte. For instance, the Li||LMTO cells cycled in LHCE show higher initial capacity of 205.2 mAh/g, and a capacity retention of 72.5 % in contrast to an initial capacity of 187.7 mAh/g and a capacity retention of 19.9 % observed in Li||LMTO cells with the conventional electrolyte after 200 cycles at a current density of 20 mA/g. This work paves the way for the development of practical DRX cathode- based high-energy Li batteries.

Scalable and Non-Destructive Analysis of Battery Degradation and Performance

Electrochemical processes occurring during battery operation are highly complex. Thermodynamic, kinetic and transport-based phenomena all play a significant role in the dynamic evolution of the time-based electrochemical response of any battery system. Researchers have long sought to quantify these various interconnected phenomena, but to-date elucidating the role these mechanisms play in the performance of battery systems has been challenging or impossible. To aid researchers in uncovering the mechanistic behavior of their systems, we have developed a novel testing protocol and corresponding data analysis method that is scalable and non-destructive (SAND). This protocol and analysis can be applied to any battery system, in any form factor, at any point in the battery life cycle; including R&D, manufacturing, and second life battery screening to name a few.The testing protocol is based on a series of galvanostatic current pulses at a variety of currents and/or times. By utilizing the natural differences in time-constant of the various electrochemical phenomena inside a battery, this technique can probe each mechanism to glean novel insight using standard battery cycling equipment. Specifically, the insights this technique can provide include: the electrochemical potential of each phase during lithiation and delithiation quantification of electrode kinetics at various states-of-charge (including exchange current density estimation from the Butler-Volmer model)quantitative estimation of transport-based polarization losses from both the electrodes and the electrolyte. This analysis provides an un-parallelled level of mechanistic insight into the inner workings of any battery, at any point, spanning small-scale R&D cells to large format cells in mass production.To demonstrate the capabilities of this technique this presentation will focus on the analysis of multiple cells (same model) from a Tier 1 supplier containing a lithium transition metal oxide cathode material cycled at various temperatures. These results have led to an extensive set of conclusions. For brevity a few of these conclusions are: The initial exchange current density of these cells is calculated to be 25.5 A/m2. The H2→H3 phase transition during charging is the least efficient phase, exhibiting the largest power loss during chargingThe inefficiencies in the H2→H3 phase transition are dominated by solid-state lithium atom diffusion within the electrodes. At low current densities the overpotential associated with transport is the dominant source of losses, while at higher currents kinetic overpotentials become the dominant source. In summary, we have developed a novel characterization technique requiring only standard battery cycling equipment that can be easily and quickly performed by researchers around the world. Whether on small-scale coin cells or large-format pouch cells, the analysis from this technique will give the battery community insight into the thermodynamic, kinetic, and transport properties of their system. Moreover, this technique can be applied in a variety of contexts related to battery development, including understanding degradation mechanisms, performing root-cause analysis of manufacturing defects, or providing more accurate parameters for computational modeling.

Waste plastics upcycled for high-efficiency H2O2 production and lithium recovery via Ni-Co/carbon nanotubes composites

The disposal and management of waste lithium-ion batteries (LIBs) and low-density polyethylene (LDPE) plastics pose significant environmental challenges. Here we show a synergistic pyrolysis approach that employs spent lithium transition metal oxides and waste LDPE plastics in one sealed reactor to achieve the separation of Li and transition metal. Additionally, we demonstrate the preparation of nanoscale NiCo alloy@carbon nanotubes (CNTs) through co-pyrolysis of LiNi0.6Co0.2Mn0.2O2 and LDPE. The NiCo alloy@CNTs exhibits excellent catalytic activity (Eonset = ~0.85 V) and the selectivity (~90%) for H2O2 production through the electrochemical reduction of oxygen. This can be attributed to the NiCo nanoalloy core and the presence of CNTs with abundant oxygen-containing functional groups (e.g., –COOH and C–O–C), as confirmed by density function theory calculations. Overall, this work presents a straightforward and green approach for valorizing and upcycling various waste LIBs and LDPE plastics.

Electrocatalytic Decomposition of Lithium Oxalate-Based Composite Microspheres as a Prelithiation Additive in Lithium-Ion Batteries.

In conventional lithium-ion batteries (LIBs), the active lithium from the lithium-containing cathode is consumed by the formation of a solid electrolyte interface (SEI) at the anode during the first charge, resulting in irreversible capacity loss. Prelithiation additives can provide additional active lithium to effectively compensate for lithium loss. Lithium oxalate is regarded as a promising ideal cathode prelithiation agent; however, the electrochemical decomposition of lithium oxalate is challenging. In this work, a hollow and porous composite microsphere was prepared using a mixture of lithium oxalate, Ketjen Black and transition metal oxide catalyst, and the formulation was optimized. Owing to the compositional and structural merits, the decomposition voltage of lithium oxalate in the microsphere was reduced to 3.93 V; when being used as an additive, there is no noticeable side effect on the performance of the cathode material. With 4.2% of such an additive, the first discharge capacity of the LiFePO4‖graphite full cell increases from 139.1 to 151.9 mAh g-1, and the coulombic efficiency increases from 88.1% to 96.3%; it also facilitates the formation of a superior SEI, leading to enhanced cycling stability. This work provides an optimized formula for developing an efficient prelithiation agent for LIBs.

Electrochemomechanical failure in layered oxide cathodes caused by rotational stacking faults.

Electrochemomechanical degradation is one of the most common causes of capacity deterioration in high-energy-density cathodes, particularly intercalation-based layered oxides. Here we reveal the presence of rotational stacking faults (RSFs) in layered lithium transition-metal oxides, arising from specific stacking sequences at different angles, and demonstrate their critical role in determining structural/electrochemical stability. Our combined experiments and calculations show that RSFs facilitate oxygen dimerization and transition-metal migration in layered oxides, fostering microcrack nucleation/propagation concurrently with cumulative electrochemomechanical degradation on cycling. We further show that thermal defect annihilation as a potential solution can suppress RSFs, reducing microcracks and enhancing cyclability in lithium-rich layered cathodes. The common but previously overlooked occurrence of RSFs suggests a new synthesis guideline of high-energy-density layered oxide cathodes.

Origins and Importance of Intragranular Cracking in Layered Lithium Transition Metal Oxide Cathodes.

Li-ion batteries have a pivotal role in the transition toward electric transportation. Ni-rich layered transition metal oxide (LTMO) cathode materials promise high specific capacity and lower cost but exhibit faster degradation compared with lower Ni alternatives. Here, we employ high-resolution electron microscopy and spectroscopy techniques to investigate the nanoscale origins and impact on performance of intragranular cracking (within primary crystals) in Ni-rich LTMOs. We find that intragranular cracking is widespread in charged specimens early in cycle life but uncommon in discharged samples even after cycling. The distribution of intragranular cracking is highly inhomogeneous. We conclude that intragranular cracking is caused by local stresses that can have several independent sources: neighboring particle anisotropic expansion/contraction, Li- and TM-inhomogeneities at the primary and secondary particle levels, and interfacing of electrochemically active and inactive phases. Our results suggest that intragranular cracks can manifest at different points of life of the cathode and can potentially lead to capacity fade and impedance rise of LTMO cathodes through plane gliding and particle detachment that lead to exposure of additional surfaces to the electrolyte and loss of electrical contact.

Layer-Type AxRhO2 (A = Li, Na, K, Rb, Cs) and KxMO2 (M = Co, Rh, Ir) Electrodes: Structure and Electrochemistry

Layered lithium transition-metal oxides have remained at the forefront since the first commercialization of layered LiCoO2 in lithium-ion batteries in 1991. The scientific interest in layered sodium transition-metal oxides as well as potassium transition-metal oxides has been considerably growing for application to sodium- and potassium-ion batteries. We extend our systematic studies on the series of layered oxides to AxRhO2 (A = Li, Na, K, Rb, Cs) and KxMO2 (M = Co, Rh, Ir) electrode system focusing on their crystal structure and electrochemical behaviors in non-aqueous cells as a function of A+ ion. Further studies on P2-type KxRhO2 in comparison to P2-type KxCoO2 show that larger Rh(III/IV) ion than Co(III/IV) is believed to be beneficial for reversibility and kinetic of redox process, accompanied with reversible structural evolution upon oxidation/reduction maintaining the P2 framework.

Chiral Molecular Coating of a LiNiCoMnO2 Cathode for High-Rate Capability Lithium-Ion Batteries.

The growing demand for energy has increased the need for battery storage, with lithium-ion batteries being widely used. Among those, nickel-rich layered lithium transition metal oxides [LiNi1-x-yCoxMnyO2 NCM (1 - x - y > 0.5)] are some of the promising cathode materials due to their high specific capacities and working voltages. In this study, we demonstrate that a thin, simple coating of polyalanine chiral molecules improves the performance of Ni-rich cathodes. The chiral organic coating of the active material enhances the discharge capacity and rate capability. Specifically, NCM811 and NCM622 electrodes coated with chiral molecules exhibit lower voltage hysteresis and better rate performance, with a capacity improvement of >10% at a 4 C discharge rate and an average improvement of 6%. We relate these results to the chirally induced spin selectivity effect that enables us to reduce the resistance of the electrode interface and to reduce dramatically the overpotential needed for the chemical process by aligning the electron spins.

Direct Recycling of β‐Li3PS4‐Based All‐Solid‐State Li‐Ion Batteries: Interactions of Electrode Materials and Electrolyte in a Dissolution‐Based Separation Process

All‐solid‐state batteries (ASSB) are currently developed at high pace and show a strong potential for market introduction within the next years. Though their performance has improved considerably over the last years, investigation of their sustainability and the development of suitable recycling strategies have received less attention. However, their potential for efficient circular processes must be accessed comprehensively. In this article, the separation of the solid electrolyte β‐Li3PS4 from different lithium transition metal oxide electrode materials (LiCoO2, LiMn2O4, LiNi0.8Mn0.1Co0.1O2, LiFePO4, LiNi0.8Co0.15Al0.05O2, and Li4Ti5O12) are investigated via an approach based on the dissolution and subsequent precipitation of the thiophosphate using N‐methylformamide as solvent. A combination of X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, inductively coupled plasma mass spectrometry, iodometric titration, and X‐ray photoelectron spectroscopy as well as electrochemical impedance spectroscopy and electrochemical characterization is used to characterize the electrolyte and electrode materials before and after separation. Herein, it is found that the presence of electrode materials in the dissolution process can lead to significant chemical reactions. These interactions can (but most not) lead to strong alteration of the electrochemical characteristics of the individual compounds. Thus, it is shown that an efficient recovery of materials likely depends on the precise material combination within an ASSB.

Method—AMIDR: A Complete Pulse Method for Measuring Cathode Solid-State Diffusivity

The Atlung Method for Intercalant Diffusion and Resistance (AMIDR) is a novel, high accuracy method for measuring solid state diffusivity and interface resistance related to the Atlung Method for Intercalant Diffusion (AMID) with several key differences. Most notably, AMIDR is designed to analyze the voltage response over time of “complete” pulses, pulses that last until an impedance steady state is reached. These differences allow for AMIDR to return diffusivity results with a higher degree of confidence than Galvanostatic Intermittent Titration Technique (GITT) and at a faster rate with higher state of charge (SOC) resolution than Electrochemical Impedance Spectroscopy (EIS). In this study, three different lithium transition metal oxides were studied. These active materials showed very similar kinetic behaviour that varied with dependence on the fraction of Ni atoms filling sites in the Li layer. AMIDR comes with a user-friendly python program complete with a user interface that is intended to assist other researchers in measuring active material diffusivity in a controlled, repeatable manner. This program, along with instruction on its use, the results of this study from raw data to the final key kinetic metrics, and a video summary of AMIDR design are available for download at https://github.com/MitchBall/AMIDR.

Quantifying Electrochemical Degradation in Single-Crystalline LiNi0.8Mn0.1Co0.1O2 –Graphite Pouch Cells through Operando X-Ray and Postmortem Investigations

Layered nickel-rich lithium transition-metal oxides (LiNixMnyCo1−x−yO2; where ≥ 0.8), with single-crystalline morphology, are promising future high-energy-density Li-ion battery cathodes due to their ability to mitigate particle-cracking-induced degradation. This is due to the absence of grain boundaries in these materials, which prevents the build-up of bulk crystallographic strain during electrochemical cycling. Compared to their polycrystalline counterparts, there is a need to study single-crystalline Ni-rich cathodes using x-ray methods in uncompromised machine-manufactured industrylike full cells to understand their bulk degradation mechanisms as a function of different electrochemical cycling protocols. This can help us identify factors to improve their long-term performance. Here, through in-house x-ray studies of pilot-line-built LiNi0.8Mn0.1Co0.1O2–graphite A7 pouch cells, it is shown that their electrochemical-capacity fade under harsh conditions (2.5–4.4 V and 40 °C for 100 cycles at a C/3 rate) primarily stems from the high-voltage reconstruction of the cathode surface from a layered to a cubic (rock-salt) phase that impedes the Li+ kinetics and increases cell impedance. Postmortem electron and x-ray microscopy show that these cathodes can withstand severe anisotropic structural changes and show no cracking when cycled under such conditions. Comparing these results to those from commercial Li-ion cells with surface-modified single-crystalline Ni-rich cathodes, it is identified that cathode surface passivation can mitigate this type of degradation and prolong cycle life. In addition to furthering our understanding of degradation in single-crystalline Ni-rich cathodes, this work also accentuates the need for practically relevant and reproducible fundamental investigations of Li-ion cells and presents a methodology for achieving this. Published by the American Physical Society 2024

Nano-rods in Ni-rich layered cathodes for practical batteries.

Lithium transition metal oxide layers, Li[Ni1-x-yCox(Mn and/or Al)y]O2, are widely used and mass-produced for current rechargeable battery cathodes. Development of cathode materials has focused on increasing the Ni content by simply controlling the chemical composition, but as the Ni content has almost reached its limit, a new breakthrough is required. In this regard, microstructural modification is rapidly emerging as a prospective approach, namely in the production of nano-rod layered cathode materials. A comprehensive review of the physicochemical properties and electrochemical performances of cathodes bearing the nano-rod microstructure is provided herein. A detailed discussion is regarding the structural stability of the cathode, which should be maximized to suppress microcrack formation, the main cause of capacity fading in Ni-rich cathode materials. In addition, the morphological features required to achieve optimal performance are examined. Following a discussion of the initial nano-rod cathodes, which were based on compositional concentration gradients, the preparation of nano-rod cathodes without the inclusion of a concentration gradient is reviewed, highlighting the importance of the precursor. Subsequently, the challenges and advances associated with the nano-rod structure are discussed, including considerations for synthesizing nano-rod cathodes and surface shielding of the nano-rod structure. It goes on to cover nano-rod cathode materials for next-generation batteries (e.g., all-solid-state, lithium-metal, and sodium-ion batteries), inspiring the battery community and other materials scientists looking for clues to the solution of the challenges that they encounter.

Toward a high-voltage practical lithium ion batteries with ultraconformal interphases and enhanced battery safety

Nickel-rich layered lithium transition metal oxides, LiNixCoyMn1-x-yO2, are key cathode materials for high-energy lithium–ion batteries owing to their high specific capacity. However, the commercial deployment of nickel-rich oxides is hampered by their parasitic reactions and the associated safety issues at high voltages. Developing a stable cathode–electrolyte interphase (CEI) is a promising strategy to overcome this problem. Herein, we report a novel approach, based on the in situ polymerization reaction, to build a protective polymer skin on LiNi0.6Co0.2Mn0.6O2 (NCM622) cathode materials. The artificial CEI skin was found to drastically improve the intrinsic thermal stability, mitigate the evolution of phase transition, and effectively inhibit the associated parasitic reactions between cathodes and the electrolyte in the high-charge states. This coating approach leads to enhanced capacity retention and battery safety under high-voltage operations. The CEI design concept offers a promising strategy for develop advanced nickel-rich cathodes for batteries.

Monitoring the Synthesis of Nickel-Poor and Nickel-Rich Oxide Cathode Materials for Lithium-Ion Batteries with Synchrotron-Based XRD and Sxas

The synthesis of Ni-poor (NCM111, LiNi1/3Co1/3Mn1/3O2) and Ni-rich (NCM811 LiNi0.8Co0.1Mn0.1O2) lithium transition metal oxides (space group R-3m ) from hydroxide precursors (Ni1/3Co1/3Mn1/3(OH)2, Ni0.8Co0.1Mn0.1(OH)2) are investigated with in situ synchrotron powder diffraction (SXPD) and near edge x-ray absorption fine structure spectroscopy (NEXAFS). The development of the layered structure of these two cathode materials proceeds via two utterly different reaction mechanisms. While the synthesis of NCM811 involves a rock salt-type intermediate phase, NCM111 reveals a layered structure throughout the entire synthesis. Moreover, the necessity and the impact of a pre-annealing step and a high-temperature holding step are discussed.

Material Selection for Fundamental Investigation of High Temperature Processes in Lithium-Ion Cathode Production

Rapid upscaling of current and near-future lithium-ion battery (LIB) technologies is one of the main remaining challenges for road transport electrification. Among cathode materials high-Ni layered lithium transition metal oxides, Li(NixCoyMn1-x-y)O2 (LNMC, x ≥ 0.7), show large potential for application in next-generation LIB’s because of their high energy density, low cost, and superior electrochemical properties 1–3.To optimize current cathode production technologies, and to select the most optimal future technologies, a thorough understanding of the synthesis fundamentals of lithium-ion cathode calcination processes is a prerequisite. In this context, in-situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA) have emerged as powerful tools for investigating the high-temperature reaction mechanism of the synthesis of these materials 4,5. However, most research does not address some challenges that come with studying complex high temperature synthesis reactions at the inherit small scale of these in-situ techniques. One issue, is that detailed information on the materials used for supporting the samples is seldomly mentioned, making it difficult to distinguish possible side reactions from the main reactions occurring during high temperature characterization. In only a limited number of studies on the high temperature interaction between ternary lithium-ion battery cathode materials and common substrate materials, evidence of direct contact-corrosion of refractory materials due to lithium compounds has been observed 6. To obtain meaningful insights from these in-situ techniques on the synthesis mechanism of LIB cathode materials that are transferable to mass production processes, these unwanted side reactions must be avoided as much as possible.The purpose of the current study is to select the optimal support material for high temperature in-situ characterization of LIB calcination processes. Several LNMC blends, containing a Li compound and a NMC precursor, were calcined in different crucible materials under a 100% O2 flow at 900 °C for 10-12 hours. The selected crucibles for this investigation include common oxide refractories: Al2O3, SiO2 (fiber and quartz) and MgO, as well as Au, as a frequently used inert material for lab scale experiments. Chemical composition of the precursor blend and calcined products are compared by inductively coupled plasma optical emission spectroscopy ICP-OES. Additionally, weight increase of each crucible material is tracked over multiple calcination cycles, and the formed corrosion products are characterized with SEM-EDS and XRD. The ICP-OES measurements show that the final Li:TM ratio of the calcined LNMC material is heavily influenced by the used crucible material, indicating that selecting an appropriate support material is crucial to avoid side reactions and thus ensure that small scale in situ characterization methods such as in-situ XRD and TGA provide relevant data. Nitta, N., Wu, F., Lee, J.T. & Yushin, G. Mater. Today 18, 252–264 (2015).Schipper, F. et al. J. Electrochem. Soc. 164, A6220–A6228 (2017).Julien, C.M. & Mauger, A. Energies 13, 6363 (2020).Wang, D. et al. Adv. Mater. 29, 1606715 (2017).Gao, M. et al. Ionics 27, 3729–3737 (2021).Zhai, P. et al. J. Eur. Ceram. Soc. 38, 2145–2151 (2018).

Is Transition Metal Dissolution a Major Degradation Process in Commercial Li-Ion Cells? Application of Impedance with Extended Sub-mHz Low-Frequency Range

Transition metal dissolution is a well-known degradation process in Li-ion batteries correlated with capacity fade1. Transition metals from a lithium transition metal oxide cathode can dissolve which causes structural changes in the crystal structure leading to deterioration of the material. Additionally, dissolved transition metals can migrate to the anode and reduce on the surface, impacting the surface activity of the anode composite and increasing its impedance.It is generally known that electrochemical performance of a Li-ion insertion battery electrode is primarily defined by the active material chemistry, further it is strongly impacted by the material and electrode-level engineering (particle size and aggregation, electrode porosity and tortuosity, electrolyte amount and properties, conductive additive and binder choice and their distribution in electrode composite). Furthermore, impedance response of an insertion electrode exhibits a strong dependence upon lithiation level (x). The specific dependence of impedance of an electrode upon x should allow to help in separating the two individual contributions of the two electrodes in a full cathode-anode battery cell. Thus, not surprisingly, Electrochemical Impedance Spectroscopy (EIS) is a common electrochemical technique of choice for degradation studies of Li-ion batteries2. Typically, EIS spectra of batteries are measured in frequency spans from MHz (laboratory cells) or kHz (commercial cells) down to mHz ranges. However, impedance measurements down to lower minimal frequencies (below 1 mHz) are often avoided from the practical reasons due to the inevitably longer measurement times being required.In the present work cylindrical commercial 18650-size high-energy NMC-Graphite(+Si) cells were electrochemically (galvanostatically) cycled at various conditions. In the constant temperature regime (10°C, 23°C, 35°C or 45°C) the tested cells were systematically cycled within various depth of discharge (DoD) ranges to observe the effect of the voltage range on the evolution (decline) of cell capacity. EIS responses were measured at different selected states of charge (SoC), with the aim to help to resolve the individual contributions of cathode and anode. State of health (SoH) of a battery was determined by current integrated capacity measurement and was periodically monitored after specific number of cycles and correlated with the impedance growth. EIS measurements down to conventional 10 mHz as well as to very low frequencies (0.1 mHz) were performed and compared to determine what additional information and insights for developing of a physics-based battery cell model and degradation modes can be obtained by including the extended low-frequency range (down to 0.1 mHz). We systematically investigated evolution (increase) of impedance of commercial Li-ion cells including the extended low-frequency range.After completion of the cycling test, post-mortem analysis of the cell components was performed on selected cells. Cells were disassembled, electrodes carefully removed, properly washed and SEM-EDX and ICP-MS analysis was performed on the cathode and anode samples. The amount of transition metals in both cathode and anode was determined.We thoroughly confirmed that the impedance of the commercial (full cells) in general increases during the decrease of capacity at all the tested conditions. Importantly, EIS spectra measured down to very low frequencies show that in addition to the (expected) increase of the real component (Re(Z)) simultaneously also the imaginary component (Im(Z)) significantly increases. We provide novel physics-based explanation of the underlying phenomena. Electrochemical characterization of the half cells prepared from the harvested electrodes in general showed a decrease in capacity and increase in voltage hysteresis for both cathode and anode – the actual changes showing strong dependence upon conditions during cycling. EDX and ICP-MS analysis revealed that the composition of the cathode active material remained practically unchanged and that the amount of the transition metals (TMs) deposited on the anode did not increase greatly with the cycling – the total amount of detected TMs remaining well below 300 ppm (relative to the amount of TMs in pristine cathode). Gilbert, J. A., Shkrob, I. A. & Abraham, D. P. Transition Metal Dissolution, Ion Migration, Electrocatalytic Reduction and Capacity Loss in Lithium-Ion Full Cells. J. Electrochem. Soc. 164, A389–A399 (2017).Meddings, N. et al. Application of electrochemical impedance spectroscopy to commercial Li-ion cells: A review. J. Power Sources 480, 228742 (2020). Figure 1. a) Typical examples of EIS response of 811-NMC-Graphite(+Si) full cells measured at SoC = 0.5 (3.705 V) down to 1 mHz (dark colors) and down to 0.1 mHz (lighter dolors) for pristine cell (black/grey), cell cycled at 23°C (blue), and cell cycled at 45°C (red). The corresponding SoH values were: 1, 0.39, and 0.39, respectively. b) Comparison of capacity of the half-cells prepared with the cathodes and anodes harvested from the initial commercial cells (panel a). Figure 1

Spherical LiMn0.7Fe0.3PO4/C Cathode Materials for Lithium-Ion Batteries

Lithium manganese iron phosphates (LiMnxFe1-xPO4) [1] are attractive as next-generation cathode materials for lithium-ion batteries because they are safer than conventional lithium transition metal oxides (e.g. LiCoO2) [2] and are Co- and Ni-free. However, due to their low electronic conductivity [3], they can deliver much lower electrochemical properties than theoretically expected one. Therefore, many researchers have focused on chemical composition, reducing primary particle size, and carbon coating. On the other hand, granulation of LiMnxFe1-xPO4 primary nanoparticles is effective in improving poor handling of LiMnxFe1-xPO4 primary nanoparticles during cathode slurry preparation. However, electrochemical properties of granulated LiMnxFe1-xPO4 have not been well studied in previous reports. In this study, the electrochemical properties of the spherical LiMn0.7Fe0.3PO4/C composed of primary nanoparticles are reported. Spherical LiMn0.7Fe0.3PO4/C was synthesized by hydrothermal method followed by granulation and carbon coating. The synthesized spherical LiMn0.7Fe0.3PO4/C was characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). Electrochemical properties of spherical LiMn0.7Fe0.3PO4/C were examined using CR2032 coin-type cells. Fig. 1 (a) shows the SEM images of spherical LiMn0.7Fe0.3PO4/C. As shown in Fig. 1 (a), spherical particle 10 μm in diameter composed of homogeneously sized primary nanoparticles were observed. Fig. 1 (b) shows the galvanostatic charge-discharge curves for spherical LiMn0.7Fe0.3PO4/C at discharge current rates of 0.2, 1, 5, and 10 C in a voltage range of 1.5–4.5 V at 30 °C. Spherical LiMn0.7Fe0.3PO4/C delivered a 0.2 C discharge capacity of 153 mAh g−1. At the 10C rate, spherical LiMn0.7Fe0.3PO4/C also delivered a high discharge capacity of 137 mAh g−1, which was 89 % of the 0.2C discharge capacity. Detailed data of our study including blended cathode of LiNiaMnbCocO2 and spherical LiMn0.7Fe0.3PO4/C will be presented in the meeting.

In-Situ Li Plating Reactions on Inorganic Solid Electrolytes for Advanced All-Solid-State Batteries

All-solid-state batteries (SSBs) using lithium metal anode are expected to realize SSBs with high energy density. This is because lithium metal anode has the lowest redox potential and the theoretical capacity of 3861 mA h g-1 is ca. ten times larger than that of commonly-used graphite anode (372 mA h g-1). In fact, lithium metal anode has been successfully used in thin-film-type SSBs and stable charge-discharge reactions are reported [1]. In SSBs, both positive and negative electrode materials are combined with solid electrolytes, and they are assembled from the initial state in general. On the other hand, conventional SSBs apply lithium transition metal oxides (LiCoO2, etc.) as the positive electrode material, and lithium metal is electrochemically plated during the charging process. Appling electrochemically-plated lithium as a anode material can simplify the battery manufacturing process and will be an effective way to form pure lithium metal anode. Such “Li-free” SSBs has been successfully prepared in thin-film-type SSBs [2]. Also, this anode-less idea has been applied to develop large-sized SSBs in recent years [3].In this presentation, the author will talk about the factors for lithium plating morphology on inorganic solid electrolytes, such as current collector species, current densities, temperature, etc. [4]. The model solid electrolytes are LiPON-coated LATP or garnet-structured Ta-doped LLZ. Also, several problems for applying electrochemically-plated lithium anode and the issues arising during the stripping processes will be discussed.

Recovery of valuable metals from spent lithium-ion batteries through biomass pyrolysis gas-induced reduction

The development of spent lithium-ion batteries (LIBs) recycling technologies can effectively alleviate environmental pressure and conserve metal resources. We propose a win-win strategy for pyrolysis gas reduction by lignocellulosic biomass, ensuring gas-induced reduction by spatial isolation of biomass and lithium transition metal oxides (LiTMOX (TM = Ni, Co, Mn)), and avoiding the separation of solid carbon and TMOX (TM = Ni, Co, Mn). In the spent LiCoO2 batteries, the lithium recovery efficiency reaches 99.99% and purity reaches 98.3% at 500 °C. In addition, biomass pyrolysis gas reduction is also applicable to treat spent LiMn2O4 and LiNi0.6Co0.2Mn0.2O2 batteries. Thermodynamic analysis verifies that CO dominates the gas reduction recovery process. DFT calculation indicates that the gas reduction induces the collapse of the oxygen framework of LiTMOX (TM = Ni, Co, Mn). Everbatt-based economic and environmental analysis illustrates that this is an environment-friendly and energy-saving method.