Spinel LiMn2O4 Cathode Material Research Articles

A modification engineering to form two kinds of truncated octahedrons by in situ LaBO3 coating for high-performance LiMn2O4 cathode material

Rapid capacity fade of spinel LiMn2O4 cathode material limits the application of lithium-ion batteries. Herein, the introduction of La/B elements achieves the dual-modification of surface coating and single-crystal truncated morphology, ensuring the compatibility of rate capability and cycling stability. The La and B introduction enables the in situ formation of LaBO3 coating layer. Both the LaBO3 coating and truncated morphology prevent the direct exposure of the cathode to the electrolyte, decreasing the Mn dissolution and providing the additional Li+ diffusion channels. The increase of La and B modification partially restrains the development of {110} crystal planes. The refinement manifests that the La3+/B3+ doping partially replaces Mn3+ of the LiMn2O4, inhibiting the Jahn-Teller effect and stabilizing the [MnO6] skeleton. Consequently, the optimized LiMn2O4@0.04LaBO3 with the favorable LaBO3 coating thickness and two truncated octahedrons exhibits the excellent electrochemical properties at high current rate. The first discharge capacities of 109.1, 104.2 and 96.9 mAh⋅g−1 are obtained, whilst the capacity retentions of 64.8 % (after 2000 cycles), 65.8 % (after 2000 cycles) and 80.5 % (after 1000 cycles) can be maintained at 5 C, 10 C and 20 C, respectively. Even at 5 C and 55 °C, the high initial discharge capacity of 113.6 mAh⋅g−1 and good cycling lifespans can be achieved. This modification strategy provides valuable insight for preparing the advanced LiMn2O4 cathode materials for lithium-ion batteries.

Regulation of morphology and particle size of spinel LiMn2O4 induced by Fe-B co-doping for high-power lithium ion batteries

The spinel LiMn2O4 cathode material shows severe capacity degradation due to Jahn–Teller distortion and dissolution of Mn during the charge-discharge process. Herein, a series of single crystal truncated octahedral of LiFe0.03BxMn1.97−xO4 (0≤x≤0.10) were synthesized by simple solid-state combustion combined with Fe-B co-doping, morphology and particle size controlling strategy. Through Fe-B co-doping, not only the LiFe0.03Mn1.97O4 containing {111}, {100} and {110} planes are successfully controlled to the particles containing only {111} and {100} planes, but also the near-nanometer particles are controlled to bigger submicron sizes. It is found that Fe-B co-doping can enhance the stability of the crystal structure, inhibit Jahn-Teller distortion and reduce the dissolution of Mn. Among them, the optimized LiFe0.03B0.08Mn1.89O4 forms a truncated octahedral single crystal particle with good crystallization and only {111} and {100} crystal faces, and the particle size is around 349.3 nm, showing exceptional high rate capacity and long cycle life. The LiFe0.03B0.08Mn1.89O4 releases a high initial discharge capacity of 107.1 mAh/g with a capacity retention of 77.7% after 1000 cycles at 10 C, which is higher than that of the LiFe0.03Mn1.97O4 (58.8%). Even at 20 C, LiFe0.03B0.08Mn1.89O4 still achieves a high reversible specific capacity (90.4 mAh/g) and outstanding long-cycle stability (81.3%, 1000th). This work provides a scientific basis for the crystal surface control and particle size control of spinel LiMn2O4, which is of great significance for the development of the next generation of high-power lithium-ion batteries.

Enhanced high-rate performance in Zn/Al dual-doped LiMn2O4 with submicron truncated structure

The Jahn-Teller effect and Mn dissolution always restrict the practical electrochemical properties of spinel LiMn2O4 cathode material. Herein, a low-temperature solid-state combustion method is employed to synthesize various truncated octahedral LiZn0.03AlxMn1.97-xO4 (x ≤ 0.08) with submicron structure. The Zn/Al dual-doping is conducive to forming {110} and {100} planes, and is also beneficial to the crystal development of LiMn2O4. It is found that as the amount of Al doping increases, the average particle size gradually decreases from 188 nm to 113 nm. In addition, the Zn/Al co-doping integrated with small particles can improve the high-rate performance. The optimal LiZn0.03Al0.03Mn1.94O4 exhibits submicron truncated octahedral morphology, high crystallinity, and good particles dispersibility. Benefiting from these structure merits, the LiZn0.03Al0.03Mn1.94O4 delivers the first discharge capacity of 113.1 mAh⋅g−1 and low capacity fade of 9.9 % after 300 cycles at 1C. It also shows the high first discharge capacity of 86.6 mAh⋅g−1 at 10C and the high capacity retention of 72.1 % after 2000 cycles. Even at ultrahigh current density of 15C and 20C, the ultralong cycling lifespans over 2000 cycles are also achieved in LiZn0.03Al0.03Mn1.94O4 cathode material. The excellent electrochemical properties are ascribed to its relatively high Li+ diffusion coefficient (1.60 × 10−11 cm2⋅s−1) and low apparent activation energy (25.45 kJ⋅mol−1) during the de-intercalation process. The Zn/Al dual-doping and submicron truncated octahedron designs of the LiMn2O4 provide a scientific reference to prepare high-performance cathode materials.

Improvement of electrochemical performance of spherical spinel LiMn2O4 cathode material coated with Al-doped ZnO (AZO) for Li-ion battery

Improvement of electrochemical performance of spherical spinel LiMn2O4 cathode material coated with Al-doped ZnO (AZO) for Li-ion battery

Boosting stability of spinel LiMn2O4 cathode materials by creating oxygen vacancies

Octahedral spinel lithium manganate dioxide (LiMn2O4, LMO) achieves remarkable electrochemical properties, but manganese dissolution during extended cycling process still cannot be well avoided. Herein, the oxygen vacancies within LiMn2O4 can be effectively modulated by extending the calcination duration. The density functional theory (DFT) calculation and experiments verified that appropriate oxygen vacancies not only promotes the structural stability, but also accelerates the charge transfer to improve the cycle performance under high C rate. Among them, the LMO sintered at 750 °C for 10 h (LMO-10) presented prominent electrochemical performance, delivering 114.58 mAh/g with the capacity retention rate of 95.90 % after 500 cycles at 5C, while the unmodified sample only exhibits 64.46 mAh/g with low retention of 63.75 %. This highly effective and facile approach to manipulate oxygen vacancies of spinel LiMn2O4 would facilitate to develop advanced cathode materials for lithium-ion batteries.

Preparation of Ni–Zn dual-doped polyhedral LiMn2O4 for endurable cycling lithium ion batteries at high rate

Jahn-Teller distortion and manganese dissolution are always the dominant problem of attenuating long cyclic performance and rate capacity of spinel LiMn2O4 cathode materials. Herein, a Ni–Zn dual-doping strategy is proposed to synthesize various LiNi0.05ZnxMn1.95-xO4 (x = 0–0.05) materials via a solid phase combustion method. All the as-prepared Ni–Zn co-doping materials have a good spinel structure with Fd3m space group and present unique polyhedron morphology with exposed (111) facets, which is conductive to relieving the manganese dissolution and Jahn-Teller effect. Moreover, the Ni–Zn co-doping gives rise to the extended Li–O bond and increased cell volume, hence boosting the favorable intercalation and deintercalation kinetics of Li+ ions. Consequently, the optimized LiNi0·05Zn0·02Mn1·93O4 cathode exhibits good electrochemical performance with the initial discharge capacity of 127.30 mAh g−1 and capacity retention of 70% after 1000 cycles at 1 C. At 5 C, an ultra-long cycle stability with a capacity retention of 61% is obtained up to 1800 cycles. Even at the high current rates of 10 C and 20 C, the relatively high first discharge capacities of 106.50 mAh g−1 and 99.40 mAh g−1 are also delivered, respectively. The Ni–Zn co-doping polyhedral LiMn2O4 will provide a solution for developing high-performance cathode materials in lithium ion battery.

Preparation of long cycle lifespan spinel LiMn2O4 cathode material by a dual-modified strategy

Spinel LiMn2O4 has been identified as a cathode material with extensive application potential for Li-ion batteries. However, during cycling, the Jahn−Teller effect and Mn dissolution have a substantial impact on its specific capacity and cycle span. Herein, combining Fe and Cr elements co-doping with single crystal truncated octahedron morphology is proposed to solve these problems. The Fe−Cr co-doping markedly restrains the Jahn−Teller effect, and promotes the development of crystal and selective growth of crystal surfaces in spinel LiMn2O4. The high exposure (111) surfaces of the truncated octahedron reduce the dissolution of Mn, and a tiny proportion of (110) and (100) surfaces increase the diffusion channels of Li+. HAADF-STEM characterization indicates that the Fe and Cr elements largely replace the Mn atoms at the octahedral 16d site. Because of these advantages, the optimal LiFe0.05Cr0.08Mn1.95-xO4 (LFCMO-8) delivers excellent electrochemical performance with 119.6 mAh·g−1 discharge capacity and 78.1% capacity retention after 500 cycles at 1 C. At comparatively higher current densities of 20 C and 30 C, the superior capacity retention ratios of 79.8% and 87.3% are still achieved after 2000 cycles. Even at 40 C, the LFCMO-8 sample can still reach 98.8% capacity retention rate after 2000 cycles. After 1000 cycles at 5 C, the LFCMO-8 sample still maintained a capacity retention of 45.4% at high temperature (55 °C). ICP-OES test combined with a V-shaped tube device indicates that the Mn dissolution of LCFMO-8 only accounted for 11.8% of LiFe0.05Mn1.95O4 (LFMO). This study serves as a meaningful reference for the preparation of high-performance LiMn2O4 cathode materials.

Corrigendum to “Review of spinel LiMn2O4 cathode materials under high cut-off voltage in lithium-ion batteries: Challenges and strategies” [J. Electroanal. Chem. 920 (2022) 116623

Corrigendum to “Review of spinel LiMn2O4 cathode materials under high cut-off voltage in lithium-ion batteries: Challenges and strategies” [J. Electroanal. Chem. 920 (2022) 116623

Efficient enhancement on crystallization and electrochemical performance of LiMn2O4 by recalcination treatment

Spinel LiMn2O4 cathode material was obtained by a recalcination treatment, which exhibits excellent crystallization and electrochemical performance. A series of test and analysis results revealed that the performance enhancement of as-prepared sample is related to the crystal structure, morphology and electrochemical properties. Owing to the recalcination treatment, the spinel LiMn2O4 presents a truncated-octahedral morphology with selective growth of the (110) and (100) crystal planes, which would effectively inhibit manganese dissolution. Moreover, the optimized sample exhibits a better crystallinity and electrochemical reversibility than that of pristine sample, which can provide a faster Li ion de-intercalation/intercalation kinetics. Hence, the spinel LiMn2O4 cathode material delivers a high initial discharge capacity of 112.3 mAh·g−1 with a good capacity retention of 90.3% after 500 cycles and an excellent rate performance. This study constructed a facile and meaningful method to prepare spinel LiMn2O4 cathode material, which may facilitate the development of lithium-ion batteries.

Alkaline-earth metal doping in spinel LiMn2O4 cathode materials for Li-ion batteries: Insights from first-principles calculations

Spinel LiMn2O4 is regarded as a promising cathode material candidate due to its advantages of environmental friendliness and low cost. However, its development is hindered by unstable cyclic performance and limited energy density. Herein, alkaline-earth metal Mg doping in spinel LiMn2O4 cathode material was investigated based on first-principles calculations. The results show that the substitution of Mg2+ for Mn3+ is thermodynamically favorable. At the same time, adjacent Mn3+ is oxidized to Mn4+, which weakens the Jahn-Teller distortion of the LiMn2O4 cathode. The study also found that Mg and O have strong coupling near the Fermi level, which improves cycling stability. In addition, it is found that alkaline-earth metal doping is beneficial to the enhancement of intercalation potential. These findings will provide a theoretical reference for improving the performance of LiMn2O4 cathode material and promote the development of LiMn2O4 in power batteries.

Enhanced electrochemical performance of manganese-based metal organic frameworks-derived spinel LiMn2O4 cathode materials by improving the Mn3+ content and oxygen vacancies

A series of LiMn2O4 cathodes with different Mn3+ contents are synthesized by a hydrothermally assisting method combined with a high-temperature solid phase process based on manganese-based metal organic frameworks (MOFs). The effect of NaOH addition on the morphology, structure and electrochemical properties of the LiMn2O4 cathode is investigated. The obtained samples all exhibit obvious octahedral morphology, corresponding to the cubic spinel structure with high crystallinity. Sample LMO-3 prepared with three times the molar amount of NaOH as PTA has the highest Mn3+ content, approximately 46.02%. The (100) and (110) crystal planes are exposed due to the higher Mn3+ content and the special truncated octahedral morphology, which endows LMO-3 with higher capacity and excellent rate performance. Specifically, the first specific capacity of LMO-3 is 140.6 mAh·g−1 at a rate of 1 C, and the capacity retention is 102.82% after 500 cycles. The corresponding capacity retention is 90.2% after 1000 cycles at 10 C. The spinel LiMn2O4 cathode synthesized by taking manganese-based MOFs as a precursor has great potential in practical applications.

Review of spinel LiMn2O4 cathode materials under high cut-off voltage in lithium-ion batteries: Challenges and strategies

• We explore the limitations of LiMn 2 O 4 cathode material at high cut-off voltage. • Presents the key strategies to improve the performance under high cut-off voltage. • The developments of electrolyte for high voltage are also particularly reviewed. The growing demand for high energy and power density in lithium-ion batteries mandates the utilization of cathode material with improved capacity and output voltage. Among various cathode materials, spinel structured lithium manganese oxide stands out for its acceptable energy density, high working voltage, excellent safety, and cost-effectiveness. Extending the upper cut-off voltage of cathode materials is realized to be a convenient way of increasing the energy density of lithium-ion batteries. Nevertheless, as charging to a higher voltage (>4.3 V vs Li/Li + ), several derogatory issues such as surface distortions, the interfacial reaction between cathode and electrolyte, and stress-induced cracking could emerge, leading to a rapid decline in capacity and cycle life. This review summarizes the failure mechanism of LiMn 2 O 4 , focusing on high voltage stability. Additionally, various modification strategies, such as doping and surface coating, are proposed to acquire high-voltage LiMn 2 O 4 . We also discuss prominent modification approaches for structural or electrolytes, such as concentration-gradient design, electrolyte additives, and solid-state electrolytes.

Improved long cycle performance of LiMn2O4 cathode material by Ni-B co-doping combined with truncated octahedron morphology

The rapid capacity fading of spinel LiMn2O4 cathode materials still suffers from Jahn-Teller effect and Mn dissolution. Herein, various spinel LiMn1.90-xNi0.10BxO4 cathode materials with truncated octahedron morphology are obtained by a solid-state combustion method. Owing to the substitution of Ni-B dual-doping for Mn, the MnO6 octahedron in the LiMn2O4 generates a contraction that leads to the increased average Mn oxidation state and the suppressed Jahn-Teller effect. Simultaneously, the expansive LiO4 tetrahedron is conducive to boosting the fast Li+ diffusion. Moreover, the growth of {110} crystal planes in the LiMn1.90-xNi0.10BxO4 (x = 0.02–0.15) is also restrained by the Ni-B co-doping, hence alleviating the Mn dissolution. So the Ni-B co-doping accompanied with truncated octahedron morphology presents the preferential growth of {111} and {100} planes. Among the various counterparts of Ni-B co-doping, the optimized LiMn1.84Ni0.10B0.06O4 exhibits the optimal rate performance and cycle life. At 5 C, a capacity retention of 73.5% with an initial discharge capacity of 101.8 mAh g−1 is achieved after ultra-long 2000 cycles. Even at 10 C, the capacity retention of 62.2% is also maintained after 2000 cycles. This combination of element doping and morphology regulation will provide a feasible strategy to synthesize high-performance spinel LiMn2O4 cathode materials for lithium-ion batteries.

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). Microwave irradiation improves the specific capacity by about 21% and capacity retention (0.022% capacity loss per cycle for the LMO-m, ∼ 0.036% capacity loss per cycle for LMO-p for 100 cycles). 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.

Regulation of morphology evolution and Mn dissolution for ultra-long cycled spinel LiMn2O4 cathode materials by B-doping

Electrochemical properties of spinel LiMn2O4 cathode material have been always suffered from Mn dissolution and Jahn-Teller distortion. Herein, various Ni/B dual-doped LiNi0.08BxMn1.92-xO4 (x = 0–0.15) with a truncated octahedral morphology are synthesized via a facile solid-state combustion. The effects of Ni/B co-doping on the morphology, crystal structure, Mn dissolution, Li+ diffusion coefficient and activation energy are investigated. Due to the relatively high Ni–O and B–O bond energy than that of Mn–O bond, the structure stability of the LiMn2O4 is enhanced, whilst restraining the Jahn-Teller distortion. The LiNi0.08Mn1.92O4 shows (111), (110) and (100) facets. In comparison, the B-doping endows the LiNi0.08BxMn1.92-xO4 (x ≥ 0.02) with (111) and (100) facets. This morphology evolution without (110) facets effectively inhibits the Mn dissolution. Owing to the synergistic merits of Ni/B dual-doping and unique truncated octahedron, the optimized LiNi0.08B0.06Mn1.86O4 delivers an initial discharge capacity of 113.9 mAh∙g−1 at 1C and maintains a durable cycling life up to 2000 cycles at 5C. Even at 20C, a capacity retention of 86.3% is still obtained after 2000 cycles. Furthermore, a capacity retention of 70.6% can be retained after 500 cycles at 5C and 55 °C. The truncated octahedral LiNi0.08BxMn1.92-xO4 with excellent electrochemical performance will be a good candidate for developing long-life lithium-ion batteries.

Preparation of spinel LiMn2O4 cathode material from used zinc-carbon and lithium-ion batteries

Due to the progressive shortage of primary resources and growing environmental concerns over industrial and household residues, proper management of electronic wastes is of great importance in addressing sustainability issues. Spent batteries are considered as important secondary sources of their constituting components. In this study, the co-recycling of used zinc-carbon and lithium-ion batteries was performed aiming at the recovery of their manganese and lithium contents as compounds which can be used as precursors for the synthesis of spinel LiMn2O4. Manganese was recovered in the form of amorphous, submicron, spherical nodules of MnO2 after acid leaching of zinc-carbon battery pastes. Lithium was obtained from nickel-manganese-cobalt (NMC) batteries as its monohydrate oxalate (C2HLiO4.H2O) through selective leaching in oxalic acid followed by crystallization. Lithium carbonate was also prepared by subsequent calcination of the oxalate. The synthesis of LiMn2O4 spinel cathode was investigated using the reclaimed Li- and Mn-containing compounds via solid-state synthesis method. The effect of such parameters as type of precursors (C2HLiO4.H2O/Li2CO3 with Mn2O3/MnO2), temperature (750, 800, and 850 °C), and time (8 and 10 h) on the synthesis of LiMn2O4 was investigated. The products were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The crystallographic parameters from XRD analysis were used to predict the electrochemical behavior of the synthesized cathode materials. Based on these, the spinel powder synthesized at 850°C−10h from Li2CO3−Mn2O3 starting mixture was determined as the cathode material with the best electrochemical properties among the synthesized samples. The galvanostatic charge/discharge evaluation within the voltage range of 2.5–4.3 V showed the specific capacity of the 850°C-10 h sample to be 127.87 mAhg−1.

Effects of Lithium Salt Addition Methods on the High-Temperature Electrochemical Performance of LiMn2O4

The poor high-temperature stability of spinel LiMn2O4 cathode material has become a bottleneck hindering its large-scale application. To enhance its high-temperature electrochemical performance, the effects of two different methods of lithium salt addition on its high-temperature electrochemical performance were studied. Two methods, Li+ infiltration and solid phase mixing, were used to prepare spinel LiMn2O4 cathode material by the same high-temperature solid phase method, respectively. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, Raman, and particle size analysis. Electrochemical performance tests were carried out on the electrochemical equipment by assembling into a half-battery. The results show that the material obtained by the lithium salt solid phase mixing method presents a loose structure composed of small primary particles to form a spherical secondary particle. However, the material obtained by the Li+ infiltration method presents an octahedral crystal structure, showing a trend toward single crystal. At the same time, its calcination time is greatly shortened (from 26 to 6 h) at the same calcination temperature. The electrochemical performance test results at 55 °C show that the LiMn2O4 prepared by Li+ infiltration has a better high-temperature electrochemical performance.

High electrochemical stability of Al-doped spinel LiMn2O4 cathode material for aqueous lithium-ion batteries

High electrochemical stability of Al-doped spinel LiMn2O4 cathode material for aqueous lithium-ion batteries

Facile combustion synthesis of amorphous Al2O3-coated LiMn2O4 cathode materials for high-performance Li-ion batteries

The unique Al2O3-coating layer can suppress the Mn dissolution and resist HF corrosion, hence stabilizing the crystal structure of spinel LiMn2O4 cathode materials.

Synthesis, Characterization and Electrochemical Properties of a Fluoride-Substituted Spinel LiMn2O4 Cathode Material

Conventional high-temperature (800 °C) synthesis of fluoride-substituted samples from LiF has been found to encounter the volatilization of fluorine and to limit the fluorine content, as reported in our earlier paper. In the present study, a fluoride-substituted spinel LiMn2O4 material was synthesized by using a solid-state reaction method with (NH4)HF2 as the fluorine source. The structure and the electrochemical properties of the synthesized samples were characterized by using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area analysis, Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and charge-discharge tests. As indicated by XRD, all samples showed a spinel cubic structure with space group Fd3m. In comparison with the pure LiMn2O4, fluoride substitution leads to an increase in the lattice parameter, as well as the crystal size, and a decrease in the oxidation state of manganese. From N2-sorption, LiMn2O3.85F0.15 was found to have the smallest specific surface area and the largest pore diameter compared to the LiMn2O4 and the LiMn2O3.95F0.05 samples. Additionally, the majority of the pores in all samples were found to be located in the region of mesopores. The results of the electrochemical study showed that a fluoride substitution into LiMn2O4 improved the initial discharge capacity of the materials. Among the synthesized samples, LiMn2O3.85F0.15 can be used as a starting material for producing better performing spinel-type cathode materials.