Spinel Cathode Research Articles

Low Temperature and Rapid Synthesis of Li‐Rich Li(Li0.17Mn0.83)2O4 Spinel Cathodes Derived from Metal‐Organic Frameworks for Lithium‐Ion Batteries

AbstractLi‐rich spinel materials (Li1+xMn2−xO4) have shown promise for lithium‐ion batteries. Nevertheless, the preparation of Li1+xMn2−xO4 faces significant challenges due to the difficulty in achieving a balance between well‐crystallized phases and stoichiometric chemistry. Moreover, the synthesis process is highly sensitive to calcination temperature and time, making it susceptible to phase transformations. Therefore, the rational selection of precursors and corresponding calcination procedures is absolutely essential. Herein, we make full use of the nature of metal‐organic frameworks (MOFs) to achieve phase‐controlled synthesis of Li(Li0.17Mn0.83)2O4 (LMO−F) spinel cathodes in 8 minutes at 500 °C. The composition and structural evolution during the pyrolysis process were systematically investigated to clarify the relationship between precursors and derivatives. Notably, the LMO−F achieved good electrochemical performance with 100.4 mAh g−1 at 50 mA g−1 after 100 cycles.

Sulfur-doped enhanced ZnMn2O4 spinel for high-capacity zinc-ion batteries: Facilitating charge transfer

ZnMn2O4 spinel is considered a promising cathode material for zinc-ion batteries due to its superior Zn2+ storage capability. However, the widespread utilization of ZnMn2O4 spinel as a high-capacity cathode material is impeded by its insufficient electrical conductivity. To tackle this limitation, we have employed a sulfur doping approach by substituting sulfur for oxygen atoms within the ZnMn2O4 lattice structure. After theoretical calculation, the charge exchange between metal Zn/Mn and surrounding coordinated atoms is enhanced after sulfur doping. The sulfur-doped ZnMn2O4 spinel effectively enhances the electrical conductivity, improving its electrochemical discharge capacity. Furthermore, the results reveals that a doping level of 20 % provided the greatest enhancement in capacitance, achieving a specific capacity of 220.1 mAh/g. This work improves the disadvantages of ZnMn2O4 at the atomic level and can provide ideas for the optimization and modification of spinel cathode materials.

(Invited) Extended Hubbard Functionals for Accurate Modeling of Li-Ion Battery Cathode Materials

Designing novel cathode materials for Li-ion batteries necessitates accurate first-principles predictions of their properties. Density-functional theory (DFT) employing standard (semi-)local functionals encounters challenges due to pronounced self-interaction errors within the partially filled d shells of transition-metal (TM) elements. Here, we demonstrate the efficacy of DFT with extended Hubbard functionals in accurately predicting the "digital" change in oxidation states of TM ions for mixed-valence phases at intermediate Li concentrations in phospho-olivine and spinel cathode materials. The resulting voltages exhibit remarkable agreement with experimental data [1,2].Our approach involves the use of onsite U and intersite V Hubbard parameters computed from density-functional perturbation theory with Lowdin-orthogonalized atomic orbitals, thus circumventing empirical factors [3,4]. Notably, the incorporation of intersite Hubbard V interactions proves indispensable for the precise prediction of thermodynamic quantities, particularly when electronic localization occurs amid inter-atomic orbital hybridization.Extending our investigation to vibrational spectroscopy, we calculate Raman spectra for these materials and find very good agreement with available experimental data [5]. Leveraging the robust and accurate computational framework based on extended Hubbard functionals, we embark on a high-throughput screening of Li-containing compounds, aiming to unveil novel and promising candidates for cathodes [6]. Our findings underscore the pivotal role of advanced DFT methodologies in advancing the discovery and design of high-performance battery materials.[1] I. Timrov, F. Aquilante, M. Cococcioni, N. Marzari, PRX Energy 1, 033003 (2022).[2] I. Timrov, M. Kotiuga, N. Marzari, Phys. Chem. Chem. Phys. 25, 9061 (2023).[3] I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B 98, 045141 (2021).[4] I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B 103, 085127 (2018).[5] L. Bastonero, N. Marzari, I. Timrov, in preparation.[6] C. Malica, L. Bastonero, M. Bercx, N. Marzari, I. Timrov, in preparation.

Synergistically improving the performance of spinel cathode for efficient oxygen reduction electrocatalyst

Optimizing the performance of ceramic fuel cells requires the creation of effective and inexpensive electrocatalysts for the oxygen reduction process. Here, we detail a plan for converting the inert spinel CoAl2O4 into a highly active and superior material for low-temperature ceramic fuel cells through Fe substitution. It turns out that the iron substitution aids in surface reconstruction, increasing oxidation-reduction reaction (ORR) activity. In addition, the reduction in energy bandgap due to Fe doping enhance the Cathode ORR performance, which may be triggered by the ions' kinetics at the surface and interface. The surface layer and Fe doping considerably aid the oxidation-reduction reaction, which creates more oxygen vacancies at the active oxygen site. The prepared materials exhibit enhanced fuel cell performance of 542 mW/cm2 at a temperature of 520 °C. Remarkably, the prepared cathode exhibits a commendable performance of 200 mW/cm2 at a temperature of 420 °C.Furthermore, the CoFe1Al1O4 cell exhibits a decreased Rp (polarization resistance) value of 0.6423 ohm-cm2 at a temperature of 520 °C, demonstrating rapid ORR kinetics. The distribution relaxation time (DRT) shows that the Cathode oxidation-reduction reaction (ORR) activity increased with Fe doping. We present a promising method for improving the oxidation-reduction reaction efficiency of low-temperature ceramic fuel cells.

Structural and chemical evolutions of a magnesium vanadium oxide cathode under electrochemical cycling in magnesium batteries

The design of cathode materials that remain chemically and structurally stable during repetitive ion insertion and extraction poses a significant challenge in developing multivalent batteries. The cycling stability of traditional metal oxide-based cathode is challenged by sluggish diffusion of multivalent cations and parasitic reactivity at interfacial regimes, including the cathode electrolyte interphase layer (CEI). Understanding the reactions at the cathode-electrolyte interface, particularly those induced by non-stoichiometric surface layers, is a crucial design parameter for both cathode materials and electrolytes. In this study, we employed multimodal analysis, including in situ and ex situ X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) to examine the surface reactions and subsequent structural and chemical evolutions of the CEI on high voltage magnesium vanadium oxide (MgV2O4) spinel cathode during the Mg2+ insertion/extraction processes. The results revealed that the presence of non-stoichiometric surface layers in the magnesium vanadium oxide cathode drive the decomposition of bis(trifluoromethanesulfonyl)imide (TFSI-) anion, leading to the formation of the CEI layer. The CEI layer could inhibit the Mg2+ ion transfer processes. Accompanying this reactivity-driven degradation, the magnesium vanadium oxide cathode undergoes pulverization, forming clusters of nanosized particles. This process likely improves cycling ability by creating new intercalation sites and shortening the diffusion pathway for the Mg2+ cations. This study demonstrates that controlling surface stoichiometry and engineering morphological properties are critical design parameters for high performance cathodes for multivalent batteries.

High-Voltage Spinel Cathode Materials: Navigating the Structural Evolution for Lithium-Ion Batteries.

High-voltage LiNi0.5Mn1.5O4 (LNMO) spinel oxides are highly promising cobalt-free cathode materials to cater to the surging demand for lithium-ion batteries (LIBs). However, commercial application of LNMOs is still challenging despite decades of research. To address the challenge, the understanding of their crystallography and structural evolutions during synthesis and electrochemical operation is critical. This review aims to illustrate and to update the fundamentals of crystallography, phase transition mechanisms, and electrochemical behaviors of LNMOs. First, the research history of LNMO and its development into a LIB cathode material is outlined. Then the structural basics of LNMOs including the classic and updated views of the crystal polymorphism, interconversion between the polymorphs, and structure-composition relationship is reviewed. Afterward, the phase transition mechanisms of LNMOs that connect structural and electrochemical properties are comprehensively discussed from fundamental thermodynamics to operando dynamics at intra- and inter-particle levels. In addition, phase evolutions during overlithiation as well as thermal-/electrochemical-driven phase transformations of LNMOs are also discussed. Finally, recommendations are offered for the further development of LNMOs as well as other complex materials to unlock their full potential for future sustainable and powerful batteries.

A real time study of the coupled electrochemical and mechanical behaviors of the spinel cathodes in LIBs.

Spinel cathode materials have great application prospects in lithium batteries (LIBs) due to their characteristics of abundant raw materials, simple preparation processes, and cobalt-free nature. During the electrochemical cycles, the specific capacity of the electrodes decreases significantly due to the dissolution of excess metal ions and mechanical degradation, which hinder their further application and development. Here, a bending curvature measurement system (BCMS) was designed to simultaneously measure the mechanical properties of the spinel cathodes during the electrochemical reaction. Three types of cathodes were chosen as the working cathode, and the coupled mechanical and electrochemical properties were analyzed to understand their degradation mechanism. During cycling, a hysteresis loop is observed for the curvature, modulus, plain strain, and stress, where LiMn2O4 (LMO) has the largest loop for the mechanical response while the LiNi0.5Mn1.5O4@Al2O3 (LNMO@Al) one has the smallest loop. Besides, the changing trend of LNMO@Al is the smallest in multiple cycles and it shows the more stable mechanical properties. This study shows from in situ mechanical measurements that the mechanical properties can greatly affect the electrochemical performance of the cathodes. These findings could offer new insights into the understanding of the electrochemical performance degradation in the spinel cathodes and can help develop strategies to enhance the performance of LIBs.

Carbothermal reduction-induced oxygen vacancies in spinel cathodes for high-performance aqueous zinc-ion batteries

The defect-engineering of low-valent vanadium spinel cathode boost the charge storage performance of aqueous zinc-ion battery.

Engineering improved strategies for spinel cathodes in high-performing zinc-ion batteries.

The development of high-performing cathode materials for aqueous zinc-ion batteries (ZIBs) is highly important for the future large-scale energy storage. Owing to the distinctive framework structure, diversity of valences, and high electrochemical activity, spinel materials have been widely investigated and used for aqueous ZIBs. However, the stubborn issues of low electrical conductivity and sluggish kinetics plague their smooth applications in aqueous ZIBs, which stimulates the development of effective strategies to address these issues. This review highlights the recent advances of spinel-based cathode materials that include the configuration of aqueous ZIBs and corresponding reaction mechanisms. Subsequently, the classifications of spinel materials and their properties are also discussed. Then, the review mainly summarizes the effective strategies for elevating their electrochemical performance, including their morphology and structure design, defect engineering, heteroatom doping, and coupling with a conductive support. In the final section, several sound prospects in this fervent field are also proposed for future research and applications.

Designing rock salt phase enriched surface in Mn-based partially disordered spinel cathode materials for mitigating degradation in Li-ion batteries

A novel Mn-based Sp-DRX electrode engineered to initiate favorable early phase transitions, effectively delaying detrimental transitions to extend battery life.

Kinetically controlled synthesis of low-strain disordered micro-nano high voltage spinel cathodes with exposed {111} facets.

High-voltage LiNi0.5Mn1.5O4 (LNMO) is one of the most promising cathode candidates for rechargeable lithium-ion batteries (LIBs) but suffers from deteriorated cycling stability due to severe interfacial side reactions and manganese dissolution. Herein, a micro-nano porous spherical LNMO cathode was designed for high-performance LIBs. The disordered structure and the preferred exposure of the {111} facets can be controlled by the release of lattice oxygen in the high-temperature calcination process. The unique configuration of this material could enhance the structural stability and play a crucial role in inhibiting manganese dissolution, promoting the rapid transport of Li+, and reducing the volume strain during the charge/discharge process. The designed cathode exhibits a remarkable discharge capacity of 136.7 mA h g-1 at 0.5C, corresponding to an energy density of up to 636.4 W h kg-1, unprecedented cycling stability (capacity retention of 90.6% after 500 cycles) and superior rate capability (78.9% of initial capacity at 10C). The structurally controllable preparation strategy demonstrated in this work provides new insights into the structural design of cathode materials for LIBs.

Lithium-Rich Spinel Cathode with Higher Energy Density for Sustainable Li-Ion Batteries Operating in Extended Potential Range

Lithium-Rich Spinel Cathode with Higher Energy Density for Sustainable Li-Ion Batteries Operating in Extended Potential Range

Evolution of Phases at the Surface and Interface of Mn Based Spinel Cathode with Coating Layer - a Spectroscopic Investigation

Surface modifications, commonly termed coatings or artificial interphases, are known to mitigate secondary reactions of charged cathodes with organic electrolyte and limit surface reconstruction. As a result, better electrochemical stability has been observed for coated cathodes in both liquid and solid electrolyte-based Li ion batteries (LIBs). However, these coatings, in contact with electrolyte, can be dynamic and evolve during processing stages or electrochemical cycling.In this work we investigate the interphases between spinel cathodes and two coating layers, LiNbO3 and Al2O3. The spinel LiMn2O4 (LMO) cathode and its doped variant LiMn1.5Ni0.5O4 (LMNO), owing to their three-dimensional structure, have high-rate and high-power capability with moderate energy density. With conventional electrolytes, the surface transition metal undergoes reduction forming thin binary or layered ternary oxides when charged beyond 4.2V (vs Li), restricting Li ion transport, and thereby compromising accessible capacity. This along with dissolution of manganese by HF (generated at the liquid electrolyte-electrode interface) restricts long-term applicability in practical LIBs thus necessitating surface coating or doping. In our experiments we choose epitaxial thin-film cathodes and thin-film coating materials. These provide large interface, and hence interphase areas, of well-defined crystal orientation, facilitating characterisation to deepen our understanding of the surface reactions occurring. We form an epitaxial film of cathode material using pulsed laser deposition (PLD) followed by controlled deposition of Al2O3 via atomic layer deposition (ALD) or LiNbO3 via PLD.We will present the detailed characterisation analysis of coated and uncoated spinel thin films. The epitaxial nature and crystal structure of deposited thin films are confirmed using thin film X-ray diffraction. Structurally, the phase diagram of Li-Mn(Ni)-O is complicated with many possible crystal structures with varying lithium content as well as different oxidation states of manganese. Hence, we employ a combination of X-ray absorption and photoelectron spectroscopies (XAS/XPS) to look at the chemical states of Mn ion in the cathode and Nb and Al ions in LiNbO3 and Al2O3 coating layers. For the as deposited fresh samples, the effect of deposition conditions is evaluated using XAS of the Mn L-edge and Al K-edge. XPS depth profiles of elemental distribution in the thin film heterostructures are obtained at three different incident X-ray energies (up to 6.6 kV) – thus providing chemical information from the surface, coating and at the interface of coating and cathode layers. Subsequently we electrochemically cycled these films in organic electrolyte against Li metal anode and further spectroscopic investigations were carried out. The effect of Al2O3 vs LiNbO3 coatings on retaining the structure of cathode material is probed and we will discuss the understanding thereby developed.

Microwave-Irradiation Suppresses the Jahn-Teller Distortion in Spinel LiMn2O4 Cathode Material for Lithium-Ion Batteries

Jahn-Teller (J-T) distortion remains the key challenge to realizing the full electrochemistry potential of the commercialized LiMn2O4 cathode material for lithium-ion batteries. In this work, the application of microwave irradiation to suppress the limiting J-T distortion in pristine LMO (LMO-p) materials and improve the electrochemistry of lithium-ion batteries has been reported. Unlike thermal heating, microwave irradiation inhibits J-T distortion. To establish the underlying science behind the impact of microwave irradiation, both the pristine (LMO-p) and the microwave-treated counterpart (LMO-m) are subjected to several characterization techniques, including synchrotron XRD, XPS, powder neutron diffraction (PND), MAS 7Li NMR, Raman and BET analysis. These techniques prove that LMO-m possesses the needed physico-chemical properties that explain: i) suppressed J-T distortion (such as an increased average Mn oxidation state (i.e., nMn ≥ 3.5+ or Mn4+/Mn3+ > 50%)), decreased lattice parameter, enhanced BET surface area, and enhanced structural crystallinity), and ii) improved electrochemical performance (such as increased specific discharge capacity, electronic and Li-ion transfer kinetics, and Coulombic efficiency). The findings in this work are relevant for the realization of low-cost and environmentally benign scale-up modification processes for LMO spinel and related cathode materials for the development of high performance lithium-ion batteries.

Speciation of Transition Metal Dissolution in Electrolyte from Common Cathode Materials

Significant capacity loss has been observed across extended cycling of lithium-ion batteries to high temperatures and high voltages. This occurs due to transition metal dissolution from the high voltage spinel or layered oxide cathode material, ion migration through the electrolyte, and deposition on the solid-electrolyte interphase (SEI) on the anode. While much research has been done to track the oxidation state of the transition metal in the cathode material or deposited on the anode, there have been mixed reports on the chemical state of the transition metal ions dissolved in the electrolyte depending on the type of cathode used. X-ray absorption near edge spectroscopy (XANES) was performed on electrolytes extracted from full cells built with four different cathode materials that were cycled at either high or standard voltages to determine the chemical state of Mn and Ni in solution. Inductively coupled plasma-mass spectrometry (ICP-MS) was performed on the anodes from these cells to determine the concentration of deposited metal ions.

Ethylene Carbonate Free Electrolytes with High Oxidative Stability for High Voltage Lnmo Spinel Cathode in Li-Ion Cells

The increasing implementation of lithium-ion batteries (LIBs) for the fast growing electric vehicle market calls for further improvements in energy density and drives research and innovation to investigate beyond state-of-the-art cell chemistries [1]. Currently, the capacity of the commonly employed transition metal oxide cathodes (NMC series) is approaching their theoretical limit. Thus, to further promote the energy density of LIBs, the most promising strategies are the adoption of a high-voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode in combination with a high energy density anode. While commercial grades of LNMO are now available, the main challenge toward their implementation is the identification of suitable electrolyte systems with high oxidative stability enabling safe operation of LNMO cathodes at voltages beyond 4.7 V vs Li/Li+, which are also compatible with advanced anode materials operating at low potential. Indeed, electrolytes represent a crucial component in LIBs, and hence a great deal of research has been focusing on the next generation electrolyte systems. These should present a wide electrochemical stability window, high ion conductivity over a wide range of temperature, good thermal stability, and the ability to form stable interphases.[2] In this work we present results on a range of novel electrolytes, based on previous publications [3-5] including super concentrated systems with unconventional solvents to improve the anodic stability, beyond LiPF6 salts to mitigate transition metal dissolution at the cathode, and phosphorous and boron-based additives to improve the stability of the solid/electrolyte interphase (SEI) at the anode. The electrolytes are comprehensively characterised in terms of ionic conductivity over a range of temperatures (see Fig. 1a), viscosity, and thermal stability. Electrochemical impedance spectra (EIS) has been carried out in symmetrical lithium // lithium cells to investigate the interphase stability evolution upon time. Linear sweep voltammetry has been conducted to investigate the anodic stability (see Fig. 1b). The systems have been then investigated in combination with high voltage LNMO cathode, graphite anodes as well as a novel silicon/graphite composite anode. The results will highlight the results achieved so far toward the identification of suitable electrolytes for high energy density Li-ion cells, while discussing the remaining challenges and strategies to mitigate them.[1] Energies 2017, 10(9), 1314, G. Berckmans, M. Messagie, J. Smekens, N. Omar, L. Vanhaverbeke, J. V. Mierlo.[2] Chem. Soc. Rev., 2021, 50, 10486, X. Fan, C. Wang.[3] J. Am. Chem. Soc., 136 (2014) p. 5039, Y. Yamada, K. Furukawa, K. Sodeyama, K. Kikuchi, M. Yaegashi, Y. Takeyama & A. Yamada.[4] Nature Communications, 7 (2016) 12032, J. Wang, Y. Yamada, K. Sodeyama, C. H. Chiang, Y. Tateyama & A. Yamada[5] J. Mater. Sci: Mat. Elec. , 30 (2019) p. 5098, H. Zhou, B. Liu, D. Xia, C. Yin & J. Li Figure 1

Inhibit the strain accumulation for 5V spinel cathode by mitigating the phase separation during high voltage stage

LiNi0.5Mn1.5O4 (LNMO) spinel cathode is a potential cathode material for high-power, low-cost lithium-ion batteries (LIBs) due to its low raw material cost, high operating voltage and efficient lithium-ion transport channel. However, LNMO suffers from structural stability due to the two-phase-transformation during charge/discharge process, leading to poor cycling performance. To address the issues, we have constructed a homogeneous aggregated LNMO cathode with a multifaceted primary particle, namely the LNMO with single-crystal secondary particles (SSP LNMO). Ex situ and in situ characterizations including the synchrotron X-ray diffraction, the neutron diffraction and full pouch cell validated that the SSP LNMO exhibit a single solid-solution reactions with a restrained lattice evolution during the delithiation/ lithiation process. This is in contrast to the normal LNMO cathode, which demonstrates a significant two-phase transition from spinel Li1−xNi0.5Mn1.5O4 to rock-salt MnO2 at high voltage. Therefore, the SSP LNMO has greatly improved cycle life compared to the normal LNMO cathode. Overall, this study demonstrates the possibility of constructing LNMO based on primary-grain morphology modulation to improve the intrinsic stability of LIBs.

Effects of natural leaching on electronic properties of common lithium manganese oxide LiMn2O4

The effects of degradation and possible leaching of lithium in the natural conditions were tested by subjecting LiMn2O4 to 3-month degradation in an open air environment. The starting material was characterized structurally using X-ray (XRD) and neutron (NPD) powder diffraction and found to crystallize in the nominal Fd-3m space group. The initial chemical composition was verified using X-ray photoelectron spectroscopy (XPS), electron microscopy (EDS) and neutron prompt gamma activation analysis (PGAA). The effects of degradation were studied by reinvestigating the samples using XRD, XPS and X-ray absorption (XAS). The studies did not find any chemical shift of manganese caused by the removal of Li or any statistically significant degradation of the starting composition suggesting that the spinel cathode material is resistant to possible Li removal due to medium term natural exposure.

Complete Metal Recycling from Lithium-Ion Batteries Enabled by Hydrogen Evolution Catalyst Reconstruction.

Mass adoption of electric vehicles and the depletion of finite metal resources make it imperative to recycle lithium-ion batteries (LIBs). However, current recycling routes of pyrometallurgy and hydrometallurgy are mainly developed for LiCoO2 and suffer from great energy inputs and extensive processing; thus, alternative versatile and green approaches are in urgent demand. Here, we report an ingenious and versatile strategy for recycling LIBs via catalyst reconstruction, using hydrogen evolution reaction as a proof of concept. Layered, spinel, and polyanion oxide cathode materials, as catalysts, are structurally transformed into hydroxides assisted by protons or hydroxide ions, facilitating complete metal extraction (e.g., Li, Co, Ni, Mn, Fe) with high leaching efficiencies approaching 100%. This recycling method is generally applicable to almost all commercial cathode systems and extended to actual spent pouch cells. Such a green hydrogen coupling approach provides a versatile and sustainable alternative to conventional approaches and has a broad impact beyond battery recycling.

Nanocomposite Li- and Mn-rich spinel cathodes characterized with a green, aqueous binder system

There is a growing need for alternatives to commercialized high-energy–density cathodes for Li-ion batteries with chemistries less dependent on Co and Ni and, in the past decade, particular attention has been placed on Li- and Mn- rich cathodes. Herein we report synthesis and characterization of Li- and Mn-rich cathode active materials (CAMs) with spinel-based nanocomposite structure having stoichiometries LixMn1.5Ni0.5O4 (x = 0.45–1.50) synthesized via liquid-feed flame spray pyrolysis. When cycled from 4.9 to 2.4 V, LixMn1.5Ni0.5O4 (x = 1.26, 1.50) exhibited energy densities greater than 1000 Wh kgCAM-1 using a green, aqueous binder system. Increasing initial Li content results in larger 1st charge capacity, which can potentially serve as a Li donor to irreversible, Li-consuming solid electrolyte interphase formation in next generation anode active materials.