LiMn2O4 Electrode Research Articles

Dextran Sulfate Sodium as Multifunctional Aqueous Binder Stabilizes Spinel LiMn2O4 for Lithium Ion Batteries

AbstractSpinel LiMn2O4 (LMO) has several beneficial properties for utilization as a cathode material for lithium‐ion batteries, including a high operating voltage, thermal stability, low cost, and eco‐friendliness. However, its application is limited by capacity fading due to structural transformation and manganese dissolution upon cycling. A method is proposed to resolve these two issues, using dextran sulfate sodium (DSS) as an aqueous binder to coat the LMO surface. DSS stabilizes the surface/interface structure of LMO by incorporating Na into the interstitial 16c sites, creating a uniform surface coating layer and promoting the formation of a homogeneous and stable cathode‐electrolyte interphase derived from the sulfate groups in DSS and enriched with LiF/LiSOxF. The aqueous DSS binder effectively suppresses the surface degradation and Mn dissolution of spinel LMO. The LMO electrode based on DSS exhibits superior cycling stability and rate performance compared with those of electrodes using the conventional poly(vinylidene difluoride) binder. These findings demonstrate the potential value of DSS as a multifunctional aqueous binder in stabilizing spinel LMO for lithium‐ion batteries.

Long-acting electrochemical lithium-recovery from original brine using super-stable spinel lithium manganate oxide

with the unprecedented demand for raw lithium, the spinel LiMn2O4 has been widely studied for electrochemical Li-recovery from salt-lake brines, but its industrialization is hindered by the poor cyclability induced by manganese dissolution and Jahn-Teller distortion within octahedral structure. In this work, Cr-doped and carbon-coated LiMn2O4 (C-LMO-Cr) electrodes prepared via coprecipitation-calcination method are employed to improve cycling stability and lithium selectivity for electrochemical Li-recovery. The results confirm the C-LMO-Cr electrode exhibits super-high retention rate of 98.76 % and 95.70 % of the initial capacity (27 mg·g−1) after 300 and 500 cycles, respectively. The carbon buffering on the C-LMO-Cr surface effectively impedes the initial manganese dissolution with the enhanced charge transfer. Moreover, the structural evolution from Raman/XPS analysis and theoretical calculations confirms that the shrinking lattice of the carbon-buffering LMO-Cr enhances Li+ selectivity and Li+ migration. When assembled in a hybrid capacitive deionization (HCDI) device, the optimal C-LMO-Cr electrode displays high adsorption capacity of ∼21 mg·g−1, moderate energy consumption of 13 Wh·mol−1(Li+) with a remarkable increase in Mg/Li ratio from 1.67 to 158 in the original brine from Jiezechaka. Therefore, these results demonstrate a promising potential of C-LMO-Cr electrodes for long-acting electrochemical lithium-recovery from original brines.

Recycling and Reuse of Mn-Based Spinel Electrode from Spent Lithium-Ion Batteries

In this paper, we introduce an environmentally friendly approach to recycle used batteries and recover highly valuable manganese-based cathode materials. This study demonstrates the feasibility of fast plasma pyrolysis to recover LiMn2O4 electrode materials (e.g., lithium manganese oxide, LMO) and demonstrate their reuse in newly assembled Li-ion cells. The electrochemical performance of as-recycled cathodes shows an initial discharge capacity of 72 mAh/g and is stable for 100 cycles at 0.1 C. After adding 20 mole % of excess LiOH, the recycled LMO after relithiation at 660 °C can deliver an initial discharge capacity of 96 mAh/g and retain a decent discharge capacity of 88 mAh/g after 50 cycles at a 0.2 C rate. Without relithiation, the as-recycled LMO cathode after heating at 1000 °C delivers the best electrochemical cycling performance, including an initial discharge capacity of 94 mAh/g and 50th cycle capacity of 91 mAh/g at a 0.2 C rate. This study highlights a feasible approach for recycling electrode materials in spent LIBs. Recycling of lithium-ion batteries and especially electrode materials is crucial for the sustained growth of the lithium-ion battery industry and reduced environmental issues.

Ex Situ Raman Mapping of LiMn2O4 Electrodes Cycled in Lithium-Ion Batteries.

In this study, we focus on the large-scale ex situ Raman mapping of LiMn2O4 (LMO) electrodes maintained at varying states of charge. A comprehensive statistical analysis has been conducted at an area of ca. 3660 μm2 on more than 3100 collected spectra for each LMO electrode sample. High-definition ex situ Raman maps provide profound insight into the lithiation process, offering an additional perspective on the mechanism of LMO intercalation. These maps clearly depict the coexistence of two phases, with evident phase transitions and state-of-charge gradients. The set of spectra with various state-of-charge has been successfully deconvoluted taking into account the two-phase character of the ongoing reaction. In addition, we performed the study on the samples operated for 50 cycles at the high C-rates and tracked their delithiation state and impurity formation. This technique serves as a complementary visualization and analytical tool alongside other bulk-type methods employed in battery diagnostics. Importantly, this ex situ Raman mapping approach is applicable to any electrode material exhibiting a Raman response.

Multistage regulation of LiMn2O4 electrode for electrochemical lithium extraction from salt-lake

The sustainable development of future energy relies significantly on the abundant lithium resources present in salt-lake brines. LiMn2O4 (LMO) electrochemical Li+ pump has garnered substantial attention due to its capacity to efficiently extract lithium resources from aqueous solutions with minimal energy consumption. However, the industrial application of LMO electrodes is often limited by Mn dissolving during cycles, as well as the complex and variable brine environment. To address these challenges, this study conducted a multistage regulation of LMO electrodes. Originally, the sol-gel technique was used to prepare CePO4 loading LMO. Due to CePO4 rivet load reforming LMO surface charge, the best-performing 1 wt% CePO4-loaded LMO exhibited a remarkable capacity retention rate of 83.8 % after 30 cycles. Subsequently, a comprehensive hydrophilic modification was applied to the entire electrode. 20%PAA-1CP-LMO//Ag system displayed an admirably release capacity of 24.7 mg·g−1 in Zabuye real brine characterized by an ultra-low Li/Na ratio, with Li/Na ratio in recovery solution reaching as high as 0.62.

Thermodynamic corrections of high salinity system for selective lithium extraction from brines with LiMn2O4/λ-MnO2

LiMn2O4/λ-MnO2 redox couple, possessing the advantage of high selectivity and intercalation capacity, is the most promising candidate for efficient electrochemically switched ion exchange (ESIX) from salt-lake brines. Currently Eh-pH diagrams are the main means for studying the dissolution mechanism of LiMn2O4/λ-MnO2 redox couple, however, the dissolution behavior obtained from experiments deviates significantly from the thermodynamic calculations. By introducing ionic strength correction into the thermodynamic calculation matrix of high salinity system, precise species distributions of Mn3+/Mn2+ are successfully predicted, which are in good accordance with the experimental results. Based on the novel thermodynamic calculations, the strong dependence between pH and the dominant species of Mn3+/Mn2+ is clarified, which in return determines the manganese dissolution (MD) behavior and intercalation capacity of the redox couple. The MD behavior differentiation between LiMn2O4 and λ-MnO2 electrodes is induced by the electrode potential and pH. At pH > 5, high capacity (>30 mg/g) and low MD ratio (<0.1 %) can be achieved. This research sheds light on the existence status of Mn3+ on the MD behavior and suggests the reasonable application range of ESIX with LiMn2O4/λ-MnO2 redox couple.

Fast and stable lithium extraction enabled by less-defective graphene supported LiMn2O4 conductive networks in hybrid capacitive deionization

Hybrid capacitive deionization (HCDI) technology for lithium (Li+) extraction from brine has received growing concern owing to its easy operation, low energy consumption, and environmental friendliness. LiMn2O4 (LMO) as an affordable Li+ extraction material offers a high theoretical capacity, while the slow ion insertion kinetics and unavoidable Mn dissolution restrict its wide usage. Herein, an LMO-based electrode supported by less-defective (inherent lattice defects and oxygen-containing defects), interconnected graphene conductive networks is proposed for fast and stable Li+ extraction from brine using HCDI. The rGO/LMO electrode displays an excellent conductivity of 0.42 S·cm−1 and a high specific capacitance of 418.26 F·g−1. In the HCDI system, the rGO/LMO electrode delivers a Li+ adsorption capacity up to 4.34 mmol·g−1 with a rapid adsorption rate of 0.33 mmol·g−1·min−1 (0.05 mol·L–1 LiCl, 1.0 V), demonstrating both of the outstanding adsorption capacity and rate abilities as defined by Ragone plots. In a solution with a high Mg2+/Li+ molar ratio of 20, the separation factor can reach 71.32. By employing rGO/LMO electrode to simulated Atacama brine, the separation factor of Li+ from Na+, K+, Ca2+, and Mg2+ are calculated to be 473.89, 74.86, 63.07, and 38.55. Particularly, the rGO/LMO electrode shows remarkable cycling stability with a capacity retention rate of 90.73 % (50 cycles). This developed less-defective graphene-wrapped LMO electrode holds significant importance in enhancing selective Li+ extraction performance with fast rate and stability.

Reduced Lattice Constant in Al-Doped LiMn2O4 Nanoparticles for Boosted Electrochemical Lithium Extraction.

Extracting lithium selectively and efficiently from brine sources is crucial for addressing energy and environmental challenges. The electrochemical system employing LiMn2O4 (LMO) electrodes has been recognized as an effective method for lithium recovery. However, the lithium selectivity and stability of LMO need further enhancement for its practical applications. Herein, the Al-doped LMO with reduced lattice constant is successfully fabricated through a facile one-step solid-state sintering method, leading to enhanced lithium selectivity. The reduced lattice constant in Al-doped LMO is proved through spectroscopic analyses and theoretic calculations. Compared to the original LMO, the Al-doped LMO (LiAl0.05Mn1.95O4, LMO-Al0.05) exhibits highercapacitance, lower resistance, and improved stability. Moreover, the LMO-Al0.05 with reduced lattice constant can offer higher Li+ diffusion coefficient and lower intercalation energy revealed by cyclic voltammetry and multiscale simulations. When employed in hybrid capacitive deionization (CDI), the LMO-Al0.05 obtains a Li+ intercalation capacity of 21.7mgg-1 and low energy consumption of 2.6Whmol-1 Li+. Importantly, the LMO-Al0.05 achieves a high Li+ extraction percentage (≈86%) with Li+/Na+ and Li+/Mg2+ selectivity of 1653.8 and 434.9, respectively, in synthetic brine. The results demonstrate that the Al-doped LMO with reduced lattice constant could be a sustainable solution for electrochemical lithium extraction.

Increasing the stability of LiMn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; electrodes under high-current-density conditions via SoC control in an electrochemical lithium recovery system

For efficient lithium recovery, the electrochemical lithium recovery (ELR) process that uses LiMn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; (LMO) electrodes with selectivity for lithium ions, has been introduced. The electrochemical system is environmentally friendly and allows for the recovery of lithium at a high yield, but the issue of manganese dissolution in LMO electrodes, decreasing their stability, remains to be solved. Herein, we suggest a solution to the existing problem through a rapid lithium recovery method that also enhances the stability of LMO electrodes through the state-of-charge (SoC) control approach. The retained discharge capacity of the system with a high current density (0.4 A/g) remains at 99.2% at 60% SoC after 300 cycles. Compared to the results under full charge/discharge operation (44.2% after 300 cycles), the proposed method demonstrates the state-of-charge (SoC) control adjustments at high current density levels to enhance the recovery rate and stability of the electrode. Additionally, high lithium-ion selectivity with a similar recovery rate is maintained at a high current density under 60% SoC operation compared to 100% SoC in lithium recovery tests. These results indicate that the SoC control strategy can increase the efficiency of ELR by improving the stability of the electrode under high-rate operational conditions.

Chemo-Mechanical Coupling Measurement of LiMn2O4 Composite Electrode during Electrochemical Cycling

Real-time monitoring of the mechanical behavior of cathode materials during the electrochemical cycle can help obtain an in-depth understanding of the working mechanism of lithium-ion batteries. The LiMn2O4 composite electrode is employed as the working electrode in this artificial cell, which is conceived and produced along with a chemo-mechanical coupling measurement system. The multi-layer beam composite electrode made of LiMn2O4 is monitored in real time using a CCD camera to track its curvature deformation. Experiments show that the curvature of the LiMn2O4 electrode decreases with the extraction of lithium ions and increases during the lithiation process. In the meantime, a theoretical framework was developed to examine the connection between curvature change and mechanical characteristics. Thus, the elastic modulus, strain, and stress of the LiMn2O4 composite electrode were extracted by combining the bending deformation and theoretical model. The results show that the elastic modulus of the LiMn2O4 composite electrode decreases from 59.61 MPa to 12.01 MPa with the extraction of lithium ions during the third cycle. Meanwhile, the stress decreases from 0.46 MPa to 0.001 MPa, and the strain reduces from 0.43 to 0. Its changes reverse during the lithiation process. Those findings could have made a further understanding of the mechanical properties in lithium-ion batteries.

Unveiling the role of Ni doping in the electrochemical performance improvement of the LiMn2O4 cathodes

Ni doping is a commonly used strategy to improve the electrochemical performance of LiMn2O4. Uncovering the structural changes of Ni-doped LiMn2O4 during electrochemical cycling, particularly at the atomic level, is important to understand the mechanism of the relationship between Ni doping and performance improvement. Herein, we investigate the chemical and structural evolutions of the Ni-doped LiMn2O4 electrodes before and after 1000 cycles at 10 C with atomic resolution and correlate them with changes in the electrochemical properties. We found that Ni2+ ions doped into the Mn 16d sites to form a more steady LiNixMn2-xO4 phase construction, which can effectively stabilize the spinel structure by hindering Jahn − Teller distortion. Comprehensive atomic imaging demonstrated that Ni doping can suppress the formation of the unexpected Mn3O4, and rock-salt MnO phases on the surface and subsurface of LiMn2O4 during cycling, which is conducive to stabilizing the MnO6 octahedron and inhibiting the migration of Mn. Resultantly, splendid long cycling stability of 88.92 % after 1000 cycles at 10 C (1 C = 148 mAh g−1) for the optimized LiNi0.05Mn1.95O4 sample is presented. Our study provides an ingenious avenue for regulating the surface optimization and reconstruction of electrode materials.

Interrelationships among Adjustable Design Parameters and Rate Performance of Porous Electrodes in Lithium‐Ion Batteries

A combination of experiments and physics-based modeling is used to highlight the complex interaction among the adjustable design parameters of porous electrodes in determining the capacity and rate performance of lithium-ion batteries (LIBs). A series of 52 LiMn2O4 electrodes are prepared with loading and porosity in the range of 10 to 30 mg cm−2 and 0.2 to 0.5, respectively, and cycled at different C-rates in front of Li. A detailed polarization analysis of the 96 discharge profiles points to the absence of any ubiquitous sharp and universal correlation between the lumped macroscopic indexes such as the electrode thickness and the battery performance. The results call for a careful attention to the nonlinear response of the LIBs to the design variations and the significance of big data analysis to reveal the peculiar interrelationships between the battery performance and the detailed features of the electrodes such as the configuration and spatial distribution of the (in)active particles.

Accelerating the Li-ion transmission of free-standing thick electrodes by using CMC-Li as ion-conducting binder

The growing demand for high energy density lithium-ion batteries (LIBs) has made the development of thick electrodes crucial. However, thick electrodes generally show poor rate capability due to the slow ionic transmission, which restricts their application. Herein, this work employed bacteria cellulose (BC) to fabricate free-standing thick LiMn2O4 (LMO) electrodes via vacuum filtration method combined with freeze-drying. Bacteria cellulose endowed thick electrodes with excellent flexibility and good mechanical strength. Simultaneously, Li+-conducting binder, that is carboxymethyl cellulose lithium (CMC-Li), was added to provide thick electrodes with promoted Li+ transmission and improved dynamic performance. The properties of CMC-Li were demonstrated in detail. Then, the structure and electrochemical performance of prepared free-standing thick electrodes were characterized systematically. More importantly, the mechanism of enhanced dynamic performance by CMC-Li was clarified clearly. This work paves a new way to prepare free-standing thick electrodes with high energy density and superior rate capability.

Island-like CeO2 decorated LiMn2O4: Surface modification enhancing electrochemical lithium extraction and cycle performance

Extracting lithium from salt lakes is an effective way to relieve the shortage of lithium resources. Electrochemical lithium extraction has attracted wide attention due to its high selectivity, eco-friendliness, and high-efficiency. Functional surface coating is an effective approach to improve the cycling performance, stability, and conductivity of the electroactive materials. In this work, LiMn2O4 (LMO) electrode materials were prepared via sol–gel method with island-like CeO2 coating (CeLMO) for lithium electrochemical adsorption from simulated brine. CeO2 is helpful to inhibit the agglomeration of active metal oxides and promote the contact and electron transfer between metal oxides. Based on the results from X-ray diffraction, X-ray photoelectron, and Raman spectroscopy, the fate of lithium intercalation and deintercalation in CeLMO is illuminated. CeLMO-2//Ag electrochemical system can produce 96% pure Li+ from Li2CO3 precipitated mother liquor, and the adsorption capacity is 36.52 mg·g−1. The capacity retention after 30 cycles was 60% at 50 mA·g−1, and the Mn dissolution loss rate is 0.016%. In summary, island-like oxide coating improves electrochemical lithium adsorption efficiency and is a promising technology for producing battery-grade lithium products.

LiMn2O4 Li-ion hybrid supercapacitors processed by nitrogen atmospheric-pressure plasma jet

LiCl–Mn(NO3)2·4H2O pastes were screen-printed on a carbon cloth substrate and furnace-calcined to convert them into LiMn2O4. The LiMn2O4 electrode was then post-processed using a nitrogen atmospheric-pressure plasma jet (APPJ). APPJ processing created oxygen vacancy defects on the electrode surface. Electrochemical tests of the Li-ion hybrid supercapacitors (Li–HSCs) were performed by cyclic voltammetry (CV) and galvanostatic charging/discharging (GCD) in 1-M Li2SO4 aqueous solution. The results indicate that proper APPJ treatment optimizes the Li–HSCs performance, whereas excessive APPJ treatment may cause material damage. After 3-min APPJ treatment at 620 °C, the Li–HSCs exhibited a maximum areal capacitance of 87.96 mF/cm2 with capacitance retention of 124.8% after a 1000-cycle CV test.

Effect of Lithium 4-Styrene Sulfonate–Based Self-Doped Polymer Electrolyte on LiMn2O4 Electrodes in Lithium-Ion Secondary Batteries

Effect of Lithium 4-Styrene Sulfonate–Based Self-Doped Polymer Electrolyte on LiMn2O4 Electrodes in Lithium-Ion Secondary Batteries

Comparative Study on Chitosans as Green Binder Materials for LiMn2O4 Positive Electrodes in Lithium Ion Batteries

AbstractThe increasing demand for lithium ion batteries consequently involves research on environmentally benign materials and processing routes. Environmentally friendly cobalt‐free, and fluorine‐free electrodes processed without organic solvents were targeted as this approach combines high work safety and sustainability with good electrochemical performance. In this study, chitosan‐based biopolymers were synthesized and systematically investigated for the first time as “green” binders for positive electrodes utilizing LiMn2O4 (LMO). In particular, chitosans with different specifically designed low and high degrees of polymerization (DP), each with comparable degree of acetylation (DA), revealed insights into the impact on the mechanical and electrochemical performance of LMO positive electrodes. Herein, low DP chitosan provided twice the adhesion strength compared to the state‐of‐the‐art binder polyvinylidene difluoride (PVdF) in LMO electrodes, thus, showing the opportunity to reduce the binder content and increase the specific energy. Electrodes with DA&lt;16 % chitosan‐based binder could deliver higher discharge capacities than cathodes using PVdF or chitosans with DA&gt;16 % in LMO||Li metal cells. Cross‐linking of chitosans with citric acid (CA) was demonstrated to significantly increase the discharge capacity up to 80 mAh g−1 at 10 C charge/discharge rate.

Pulsed electric field controlled lithium extraction process by LMO/MXene composite electrode from brines

Low-cost and highly efficient extraction of lithium from brine is the key to solving energy and environmental problems for sustainable development. The electrochemical lithium extraction method is of high selectivity, low energy consumption and environmental friendly. In this work, two innovations were proposed for electrochemical lithium extraction technology. Firstly, the layered Ti3C2-MXene was combined with a LiMn2O4 (LMO) electrode to reduce the damage to the LMO crystal structure caused by manganese dissolution and the Jahn-Teller effect, and to greatly improve the lithium-ion transport rate and the cyclic stability of the electrode material. The good cyclic stability and high capacity were verified by XRD, SEM, and electrochemical tests before and after cycling. Secondly, the influence of four electric field controlling modes, namely constant current (CC) mode, pulse-rest(P10r2 and P10r10), pulse-rest-reverse pulse(P12r2R2), on the selectivity of lithium extraction was studied in simulated brine with an initial lithium/sodium ratio as low as 0.01. The results show that the Pulse Electric Field controlling method can effectively improve the lithium/sodium separation coefficient. Finally, an actual lithium extraction test was carried out in Atacama salt Lake brine with an initial Li/Na ratio of about 0.06. The Li/Na separation coefficient reached 1020 under the optimized electrode material structure and electric field mode. In conclusion, the application of LMO/MXene electrode under the pulse electric field mode is a highly selective method for lithium extraction with low initial lithium/sodium ratios.

Graphene decorated LiMn2O4 electrode material for hybrid type energy storage devices

AbstractLithium‐ion capacitors (LICs) are becoming useful owing to their high energy and power densities. LICs show enhance capacitance than electric double‐layer capacitance (EDLC) and pseudocapacitors, due to their battery electrode material, which can operate over a higher voltage window. LiMn2O4 is fast emerging electrode material for energy storage devices. The major limitation associated with it is the low conductivity. Therefore, to simultaneously improve the electrical conductivity as well as the electrochemical performance, a novel strategy of decoration LiMn2O4 with graphene is being proposed. Graphene will improve electrical conductivity while contributing to EDLC and pseudocapacitance values. A cost‐effective synthesis protocol is utilized to obtain conical pyramid‐type particles. These particles were thoroughly characterized using a large number of experimental techniques. Cyclic voltammetry and charge‐discharge measurements were used to evaluate the electrochemical characteristics, in 0.0 to 1.2 V stable window, using 1M LiOH electrolyte. Graphene decorated LiMn2O4 electrode show improved cyclic stability and higher specific capacitances 250 F/g in comparison to LiMn2O4 electrode. The cycling stability of the electrode was above 90% up to 3000 cycles at a higher current density.

Coulometric ion sensing with Li+-selective LiMn2O4 electrodes

A coulometric signal readout method, which was originally developed for solid-contact ion-selective electrodes, was investigated in this work using LiMn2O4 (LMO) as a combined ion-recognition and signal-transduction layer. The redox process of LMO, which is associated with reversible intercalation/expulsion of Li+ ions, allowed coulometric sensing of Li+ ions in aqueous solutions. On increasing the active area (mass loading) of LMO, the coulometric signal increased for a given change in Li+ ion activity. The excellent redox reversibility of LMO and its relatively low resistance were instrumental in achieving a high signal amplification together with a relatively fast response. Coating the LMO layer with a conventional Li+-selective plasticized PVC membrane was found to dramatically lower the coulometric response. Hence, the application of LMO as a combined Li+-selective electrode material and ion-to-electron transducer was found to be highly compatible with the coulometric signal readout method, especially for detecting small Li+ activity changes at high Li+ concentrations.