LiMn2O4 Research Articles

Strengthening Aqueous Electrolytes without Strengthening Water.

Aqueous electrolytes typically suffer from poor electrochemical stability; however, eutectic aqueous solutions-25 wt.% LiCl and 62 wt.% H3 PO4 -cooled to -78 °C exhibit a significantly widened stability window. Integrated experimental and simulation results reveal that, upon cooling, Li+ ions become less hydrated and pair up with Cl- , ice-like water clusters form, and H⋅⋅⋅Cl- bonding strengthens. Surprisingly, this low-temperature solvation structure does not strengthen water molecules' O-H bond, bucking the conventional wisdom that increasing water's stability requires stiffening the O-H covalent bond. We propose a more general mechanism for water's low temperature inertness in the electrolyte: less favorable solvation of OH- and H+ , the byproducts of hydrogen and oxygen evolution reactions. To showcase this stability, we demonstrate an aqueous Li-ion battery using LiMn2 O4 cathode and CuSe anode with a high energy density of 109 Wh/kg. These results highlight the potential of aqueous batteries for polar and extraterrestrial missions.

Low Temperature Epitaxial LiMn2O4 Cathodes Enabled by NiCo2O4 Current Collector for High-Performance Microbatteries.

Epitaxial cathodes in lithium-ion microbatteries are ideal model systems to understand mass and charge transfer across interfaces, plus interphase degradation processes during cycling. Importantly, if grown at <450 °C, they also offer potential for complementary metal-oxide-semiconductor (CMOS) compatible microbatteries for the Internet of Things, flexible electronics, and MedTech devices. Currently, prominent epitaxial cathodes are grown at high temperatures (>600 °C), which imposes both manufacturing and scale-up challenges. Herein, we report structural and electrochemical studies of epitaxial LiMn2O4 (LMO) thin films grown on a new current collector material, NiCo2O4 (NCO). We achieve this at the low temperature of 360 °C, ∼200 °C lower than existing current collectors SrRuO3 and LaNiO3. Our films achieve a discharge capacity of >100 mAh g-1 for ∼6000 cycles with distinct LMO redox signatures, demonstrating long-term electrochemical stability of our NCO current collector. Hence, we show a route toward high-performance microbatteries for a range of miniaturized electronic devices.

Dynamic Zn/Electrolyte Interphase and Enhanced Cation Transfer of Sol Electrolyte for All-Climate Aqueous Zinc Metal Batteries.

Zn metal as one of the promising anodes of aqueous batteries possesses notable advantages, but it faces severe challenges from severe side reactions and notorious dendrite growth. Here, ultrathin nanosheets of α-zirconium phosphate (ZrP) are explored as an electrolyte additive. The nanosheets not only create a dynamic and reversible interphase on Zn but also promote the Zn2+ transportation in the electrolyte, especially in the outer Helmholtz plane near ZrP. Benefited from the enhanced kinetics and dynamic interphase, the pouch cells of Zn||LiMn2 O4 using this electrolyte remarkably improve electrochemical performance under harsh conditions, i.e. Zn powders as the Zn anode, high mass loading, and wide temperatures. The results expand the materials available for this dynamic interphase, provide an insightful understanding of the enhanced charge transfer in the electrolyte, and realize the combination of dynamic interphase and enhanced kinetics for all-climate performance.

Mechanochemical enhanced lithium selective extraction from spent cathode material via two-step molten salt treatments

The rapid development and widespread use of lithium-ion batteries (LIBs) in electric vehicles and stationary energy storage systems has been stimulated by the global push toward carbon neutrality. Thus, recycling spent LIBs as an efficient way to cope with the resulting resource scarcity and environmental damage has attracted much attention. Herein, based on previous studies, a process for selective Li extraction from a recovered spent LiMn2O4 (LMO) cathode with two-step molten salt treatments is proposed in this paper. The selective extraction of Li from the spent LMO cathode by (NH4)2SO4 molten salt is significantly promoted by mechanochemical treatment. Approximately 100% of the Li in the spent LMO is selectively extracted after step two of the molten salt treatment, and the Mn-containing phases in the spent LMO cathode are converted to Mn2O3. A Li2SO4·H2O product satisfying the requirements of Standard YS/T 1241–2018 is obtained from the purified Li2SO4 water-leachate after crystallization and calcination. In addition, 93.65% Mn in the water-leaching residue of Mn2O3 achieved sulfate conversion with (NH4)2SO4 molten salt reduction, and a first-grade product of MnSO4·H2O satisfying the requirements of Standard HG/T 4823–2015 was obtained after water-leaching and crystallization.

Photothermal-Conversion-Enhanced LiMn2O4 Pouch Cell Performance for Low-Temperature Resistance: A Theoretical Study

Lithium-ion batteries (LIBs) suffer from charging difficulties, capacity decay, and severe ageing in a low-temperature environment. In this work, we suggest a theoretical study and strategy for improving the low-temperature resistance of LiMn2O4(LMO) pouch cells, by introducing a photothermal conversion layer composed of copper and single-walled carbon nanotubes. A three-dimensional electrochemical–thermal coupling model for a lithium manganate battery is established, in which the photothermal conversion layer is attached on the surface of the cathode collector, and the effect of lug design is also discussed. The changes in the battery temperature field, and improvements in electrochemical performance before and after light preheating, are analyzed. The results show that, when the photothermal conversion film is applied, the LMO pouch cell’s temperature rises 2.7 °C/min in a −5 °C environment, and the surface-temperature averaging is improved. The concentration of lithium embedded in the anode is significantly increased, and the charging speed is enhanced by 20%. The batteries with a single-sided lug design exhibit better performance compared with those with a two-sided lug design. Validation of the presented model is performed, by comparing it with the experimental Panasonic UF653445ST commercial battery datasheet. This work provides theoretical guidance on improving the low-temperature performance of pouch cells, based on the photothermal conversion method.

Magnetic Field-Enhanced Performance of Superparamagnetic LiMn2 O4 -Based Composite Slurry Electrode for Semisolid Flow Battery.

Semisolid flow batteries are expected to be applied to large-scale energy storage fields due to the combination of the high energy density of rechargeable batteries and the flexible design of flow batteries. However, electronic conductivity, specific capacity, and viscosity of slurry electrodes are generally mutually restrictive. Here, a new concept of semisolid flow batteries based on magnetic modification slurry electrode is proposed and the electrochemical performance of the semisolid electrode is expected to be improved by close contact and enhanced electronic conductivity between the active particles with the aid of external magnetic field. This concept is further demonstrated using superparamagnetic LiMn2 O4 -Fe3 O4 -carbon nanotube composite as semisolid cathode. It achieves a capacity of 113.7 mAh g-1 at a current density of 0.5mA cm-2 with the aid of external magnetic field (about 0.4 T), which is about 21% higher than that without external magnetic field. Simulation study also reveals this improvement mainly resulted from the increase of the conductive paths of electrons after the rearrangement of the active particles under the external magnetic field. It is believed that this strategy gives a new and effective method for controlling the viscosity and electronic conductivity of the slurry electrodes and related flowable electrochemical energy storage systems.

Interface dual-engineering strategy boosting the excellent high-temperature electrochemical properties of LiMn2O4

LiMn2O4 (LMO) has established its own niche in the highly competitive market of cathode materials. However, issues such as oxygen evolution, manganese dissolution, and electrolyte decomposition have hampered its further development. To address these challenges, a simple and effective strategy has been proposed, which involves incorporating WO2.72 as an oxygen vacancy inducer into LMO to enhance its structural stability. It is demonstrated that WO2.72 can induce the formation of oxygen vacancies on the material surface, which aids in the adsorption and storage of active oxygen. The vacancies also reduce the energy barrier for the migration of lithium ions, thus improving the electrochemical performance of the battery. Additionally, the formation of a Li2WO4 coating helps to eliminate residual lithium and improve the interface between the electrode and electrolyte. Accordingly, the WO2.72-modified LMO exhibits a more stable bulk structure and a better electrode-electrolyte contact interface, resulting in superior electrochemical performance. The optimized W4000 sample demonstrates outstanding cycle performance, with a capacity retention of 90.4% after 300 cycles at 10 C, which is significantly higher than that of bare LMO (68.9%).

Direct Probing of Lattice-Strain-Induced Oxygen Release in LiCoO2 and Li2 MnO3 without Electrochemical Cycling.

Since the recognition of a significant oxygen-redox contribution to enhancing the capacity of Li transition-metal oxide cathodes, the oxygen release and subsequent structural variations together with capacity fading have been critical issues to achieve better electrochemical performance. As most previous reports dealt with the structural degradation of cathodes after electrochemical cycling, it has been fairly difficult to clarify how substantial the effect of lattice strain on the oxygen release would be while exclusively ruling out any electrochemical influences. By utilizing nanoindentation and mechanical surface polishing of single-crystal LiCoO2 and Li2 MnO3 , we scrutinize the local variations of both the atomic structure and oxygen content. Atomic-column-resolved imaging reveals that local Li-M (M = Co and Mn) disordering and further amorphization are induced by mechanical strain. Moreover, substantial oxygen deficiency in the regions with these structure changes is directly identified by spectroscopic analyses. Ab initio density functional theory calculations also demonstrate energetically favorable formation of oxygen vacancies under shear strain. Providing direct evidence of oxygen release as a consequence of lattice strain, the findings in this work suggest that efficient strain relaxation will be of great significance for longevity of the anion framework in layered oxide cathodes. This article is protected by copyright. All rights reserved.

A versatile strategy to activate self-sacrificial templated Li2MnO3 by defect engineering toward advanced lithium storage

Despite the dazzling theoretical capacity, the devasting electrochemical activity of Li2MnO3 (LMO) caused by the difficult oxidation of Mn4+ impedes its practical application as the lithium-ion battery (LIB) cathode. The efficacious activation of the Li2MnO3 by importing electrochemically active Mn3+ ions or morphological engineering is instrumental to its lithium storage activity and structural integrity upon cycling. Herein, we propose a conceptual strategy with metal-organic frameworks (MOFs) as self-sacrificial templates to prepare oxygen-deficient Li2MnO3 (Ov-LMO) for exalted lithium storage performance. Attributed to optimized morphological features, LMO materials derived from Mn-BDC (H2BDC = 1,4-dicarboxybenzene) delivered superior cycling/rate performances compared with their counterparts derived from Mn-BTC (H3BTC = 1,3,5-benzenetricarboxylicacid) and Mn-PTC (H4PTC = pyromellitic acid). Both experimental and theoretical studies elucidate the efficacious activation of primitive LMO materials toward advanced lithium storage by importing oxygen deficiencies. Impressively, Ov-LMO derived from Mn-BDC (Ov-BDC-LMO) delivered intriguing reversible capacities (179.2 mA h g−1 at 20 mA g−1 after 200 cycles and 100.1 mA h g−1 at 80 mA g−1 after 300 cycles), which can be attributed to the small particle size that shortens pathways for Li+/electron transport, the enhanced redox activity induced by abundant oxygen vacancies, and the optimized electronic configuration that contributes to the faster lithium diffusivity. This work provides insights into the rational design of LMO by morphological and atomic modulation to direct its activation and practical application as an advanced LIB cathode.

Beneficial Effects of La0.5Sr0.5CoO3 Coatings on Thin‐Film LiMn2O4 Cathodes for Lithium Ion Batteries

AbstractThe severe capacity loss of spinel LiMn2O4 (LMO) limits the utility of this otherwise promising lithium ion battery cathode material. One of the strategies to mitigate capacity fade is applying a coating on LMO particle surfaces. While this approach yields promising results, there is limited understanding of mechanisms whereby coatings improve LMO capacity retention. Herein, the effects of a new protective coating material, La0.5Sr0.5CoO3 (LSCO), in a thin‐film battery geometry that is amenable to fundamental studies of electrode processes, are reported. RF sputtering deposition is used to produce high quality 25–100 nm LMO cathodes on Al2O3 substrates with an intervening Pt/Ti back‐side contact layer. Cycling of the un‐coated cathodes results in capacity loss of 18% over 300 cycles. Adding a 2 nm LSCO layer reduces the capacity loss to 3%. While this may be due in part to reduced Mn dissolution, scanning transmission electron microscopy results indicate that the coating helps to preserve crystallinity and reduce lattice structure distortion due to inhibited formation of defect tetragonal spinel. Three‐electrode electrochemical impedance spectroscopy results reveal that the LSCO coating increases charge transfer and ohmic resistances, but the increases are generally too small to significantly impact cell performance even at high C‐rates.

Spinel LiMn2O4 as Electrocatalyst toward Solid-State Zinc–Air Batteries

Efficient oxygen reduction reaction (ORR) electrocatalysts are the key to advancement of solid-state alkaline zinc–air batteries (ZAB). We demonstrate an electrocatalyst, spinel lithium-manganese oxide LiMn2O4 (LMO) by a simple hydrothermal method. Scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectra indicate that the as-synthesized LiMn2O4 presents nanoscale irregular-shaped particles with the well-known spinel structure. The polarization curve, chronoamperometery curve, and linear scanning voltammograms of rotating disk electrode (RDE) results reveal that the as-synthesized LiMn2O4 possesses a higher electrocatalytic activity than that of electrolytic manganese dioxide for the ORR. A solid-state zinc–air cell with LiMn2O4 as the air electrode catalyst has a long voltage plateau of discharge and a discharge capacity of 188.4 mAh at a constant discharge current density of 10 mA·cm−2. In summary, spinel LiMn2O4 in which the JT effect enables electron hoping between Mn3+ and Mn4+ can be regarded as an effective robust oxygen reduction catalyst.

Particle size control and electrochemical lithium extraction performance of LiMn2O4

With the unprecedented heat of lithium resources, it has been a hot topic to find an effective, low-energy-consumption, and eco-friendly method for extracting lithium from salt lakes. As an electrochemically active material, LiMn2O4(LMO) is widely used in electrochemical lithium extraction. In order to reduce the Mn dissolution loss and improve the cycle stability of LMO, we designed octahedral LMO with controllable particle size by adjusting the water/ethanol volume ratio of the precursor solution. Through the electrochemical performance test, it was found that with the increase in particle size, the cycle stability of LMO and the lithium ion transport performance also improved. The Mn dissolution loss per 30 cycles of LMO (B-LMO) was 0.187%, and the capacity was maintained at the initial 86.9%. The electrochemical lithium extraction system of B-LMO//Ag exhibits excellent lithium extraction performance. After 1 h of extraction, the lithium extraction capacity is 20.6 mg/g, and the energy consumption is 15.2 Wh/mol.

Unraveling the Mechanism and Practical Implications of the Sol-Gel Synthesis of Spinel LiMn2O4 as a Cathode Material for Li-Ion Batteries: Critical Effects of Cation Distribution at the Matrix Level.

Spinel LiMn2O4 (LMO) is a state-of-the-art cathode material for Li-ion batteries. However, the operating voltage and battery life of spinel LMO needs to be improved for application in various modern technologies. Modifying the composition of the spinel LMO material alters its electronic structure, thereby increasing its operating voltage. Additionally, modifying the microstructure of the spinel LMO by controlling the size and distribution of the particles can improve its electrochemical properties. In this study, we elucidate the sol-gel synthesis mechanisms of two common types of sol-gels (modified and unmodified metal complexes)-chelate gel and organic polymeric gel-and investigate their structural and morphological properties and electrochemical performances. This study highlights that uniform distribution of cations during sol-gel formation is important for the growth of LMO crystals. Furthermore, a homogeneous multicomponent sol-gel, necessary to ensure that no conflicting morphologies and structures would degrade the electrochemical performances, can be obtained when the sol-gel has a polymer-like structure and uniformly bound ions; this can be achieved by using additional multifunctional reagents, namely cross-linkers.

ИССЛЕДОВАНИЕ КАТОДНЫХ МАТЕРИАЛОВ ОТРАБОТАННЫХ ЛИТИЙ-ИОННЫХ АККУМУЛЯТОРОВ

The physicochemical characteristics of fresh and spent cathode material type LiCoO2 (LCO), LiNi1-x-yMnxCoy (NMC), LiMn2O4 (LMO), LiFePO4 (LFP) of spent lithium-ion batteries (LIA) have been determined. The results of a comparative analysis of the properties of the cathode materials of spent LIBs with the initial cathode material used in the creation of different types of LIBs are presented. It has been established that the particles of cathodes of spent LIА contain particles up to 100 µm in size due to sintering.

Spent lithium manganate batteries for sustainable recycling: A review

Lithium-ion batteries (LIBs) account for the majority of energy storage devices due to their long service life, high energy density, environmentally friendly, and other characteristics. Although the cathode materials of LIB led by LiFePO4 (LFP), LiCoO2 (LCO), and LiNixCoyMn1-x-yO2 (NCM) occupy the majority of the market share at present, the demand of LiMn2O4 (LMO) cathode battery is also increasing year by year in recent years. With the rising price of various raw materials of LIBs and the need of environmental protection, the efficient recycling of spent LIBs has become a hot research topic. At present, the recycling of spent LIBs mainly focuses on LFP, LCO, and NCM batteries. However, with the continuous improvement of people’s safety of LIBs, LiMnxFe1-xPO4 (LMFP) batteries show better potential, which also improves the recycling value of LMO batteries. Therefore, this paper reviews current methods of spent LMO recovery, focusing on the characteristics of the recovery and separation process, which can serve as a reference for subsequent research on LMO recovery, increasing environmentally friendly recovery routes. Finally, the future development direction of LIBs recycling is prospected. Overall, this review is helpful to understand the current progress of LMO battery recycling.

Recycling Valuable Metals from Spent Lithium-Ion Batteries Using Carbothermal Shock Method.

Pyrometallurgy technique is usually applied as a pretreatment to enhance the leaching efficiencies in the hydrometallurgy process for recovering valuable metals from spent lithium-ion batteries. However, traditional pyrometallurgy processes are energy and time consuming. Here, we report a carbothermal shock (CTS) method for reducing LiNi0.3 Co0.2 Mn0.5 O2 (NCM325) cathode materials with uniform temperature distribution, high heating and cooling rates, high temperatures, and ultrafast reaction times. Li can be selectively leached through water leaching after CTS process with an efficiency of >90 %. Ni, Co, and Mn are recovered by dilute acid leaching with efficiencies >98 %. The CTS reduction strategy is feasible for various spent cathode materials, including NCM111, NCM523, NCM622, NCM811, LiCoO2 , and LiMn2 O4 . The CTS process, with its low energy consumption and potential scale application, provides an efficient and environmentally friendly way for recovering spent lithium-ion batteries.

A green repair pathway for spent spinel cathode material: Coupled mechanochemistry and solid-phase reactions

A way of directly repairing spent lithium-ion battery cathode materials is needed in response to environmental pollution and resource depletion. In this work, we report a green repair method involving coupled mechanochemistry and solid-state reactions for spent lithium-ion batteries. During the ball-milling repair process, an added manganese source enters into the degraded LiMn2O4 (LMO) crystal structure in order to fill the Mn vacancies formed by Mn deficiency due to the Jahn–Teller effect, thereby repairing the LMO's chemical composition. An added carbon source acts not only as a lubricant but also as a conductor to improve the material's electrical conductivity. Meanwhile, mechanical force reduces the crystal size of the LMO particles, increasing the amount of active sites for electrochemical reactions. Jahn–Teller distortion is successfully suppressed by cation disorder in the LMO material. The cycling stability and rate performance of the repaired cathode material are thereby greatly improved, with the discharge specific capacity being more than twice that of commercial LMO. The proposed solid-state mechanochemical in situ repair process, which is safe for the environment and simple to use, may be extended to the repair of other waste materials without consuming highly acidic or alkaline chemical reagents.

Improved Performance of a Ni, Co-Doped LiMn2O4 Electrode for Lithium Extraction from Brine

Electrochemical extraction of Li+ from salt lakes has the characteristics of high efficiency and low energy consumption, now becoming a research hotspot. The asymmetric lithium capacitor composed of de-lithiated Li1–xNi0.025Co0.025Mn1.95O4 (LNCMO) and activated carbon is used as a system for electrochemical recovery of Li+. The consequence of cyclic voltammetry shows that lithium-ion diffusion is a process control step and Ni, Co doping is beneficial to improving the diffusion of lithium ions in the low-potential oxidation process and high-potential reduction process. The discharge capacity of LNCMO during a 50-cycle process is 122 mAh g–1 with a retention rate of 97.93% at 1 C, which is higher than that of the LiMn2O4 (LMO)/AC system (107 mAh g–1 with a retention rate of 83.92%), proving that Ni, Co doping restrains the disproportionation reaction of LMO and increases the Li+ diffusion coefficient of LMO, leading to a higher capacity and better cycle performance in brine. In 30 mM LiCl solution, the Li+ extraction capacity of 1.86 mmol g–1 is obtained with an energy of 3.97 Wh mol–1 Li+ under the optimal extraction conditions (i = 0.75 mA, T = 20 min). After 15 times of Li+ insertion/extraction in simulated brine/recovery solution, the purity of the recovery solution reached 94.59%, indicating that the LNCMO/activated carbon system has good selectivity for Li ions and stability.

Nanotechnology used in Li-ion Battery for Electric Vehicles

In recent years, environmental issues have been given increasing attention, and electric vehicles have replaced conventional combustion engined vehicles as a critical focus for development. In order to win the market, electric vehicles (EVs) must have sufficiently good performance, such as a longer mileage range, long cycling life, and time-saving charging, and the performance of the battery is one of the essential factors determining the performance of the EVs. In order to make more environmentally friendly electric vehicles available, the performance of lithium-ion batteries, which are the mainstream EV batteries, must be improved, and nanotechnology can facilitate this process. This report summarizes four promising materials for the cathodes and anodes of lithium batteries for electric vehicles and how nanotechnology can improve them. For LiMn2O4 (LMO), LiNi1-x-yMnxCoyO2 (NMC), and LiNiCoAlO2 (NCA) as cathode materials and Li4Ti5O12 (LTO) as anode material, nano-doping, nano-structuring, and surface coating are effective techniques to enhance the stability and rate capacity, and cycle performance of the battery. In the case of LMC, nanotechnology can help solve the Jahn-Teller distortions and stabilize the structure; for NMC, nanotechnology can suppress ion dissolution and chemical reactivity. For NCA, it can strengthen conductivity and capacity. And finally, for LTO, nanotechnology can faster charge/discharge rate. This paper looks forward to the maturation of these nanotechnologies and their practical application, and the identification of more nanotechnologies that can enhance the performance of Li-ion batteries to help make electric vehicles more usable and contribute to environmental development.

Nanocomposite Engineering of a High-Capacity Partially Ordered Cathode for Li-Ion Batteries.

Understanding the local cation order in the crystal structure and its correlation with electrochemical performances has advanced the development of high-energy Mn-rich cathode materials for Li-ion batteries, notably Li- and Mn-rich layered cathodes (LMR, e.g., Li1.2 Ni0.13 Mn0.54 Co0.13 O2 ) that are considered as nanocomposite layered materials with C2/m Li2 MnO3 -type medium-range order (MRO). Moreover, the Li-transport rate in high-capacity Mn-based disordered rock-salt (DRX) cathodes (e.g., Li1.2 Mn0.4 Ti0.4 O2 ) is found to be influenced by the short-range order of cations, underlining the importance of engineering the local cation order in designing high-energy materials. Herein, the nanocomposite is revealed, withaheterogeneous nature (like MRO found in LMR) of ultrahigh-capacity partially ordered cathodes (e.g., Li1.68 Mn1.6 O3.7 F0.3 ) made of distinct domains of spinel-, DRX- and layered-like phases, contrary to conventional single-phase DRX cathodes. This multi-scale understanding of ordering informs engineering the nanocomposite material via Ti doping, altering the intra-particle characteristics to increase the content of the rock-salt phase and heterogeneity within a particle. This strategy markedly improves the reversibility of both Mn- and O-redox processes to enhance the cycling stability of the partially ordered DRX cathodes (nearly ≈30% improvement of capacity retention). This work sheds light on the importance of nanocomposite engineering to develop ultrahigh-performance, low-cost Li-ion cathode materials.