LiMn2O4 Cathode Research Articles

Nanostructured ZnxMn3‒xO4 thin films by pulsed laser deposition: A spectroscopic and electrochemical study towards the application in aqueous Zn-ion batteries

Aqueous Zn-ion batteries (AZIBs) represent a safe and sustainable technology amongst the post-lithium systems, though the poor understanding of the material behaviour at the cathode prevents the full development of efficient AZIBs. ZnMn2O4 (ZMO) has been considered one of the cathode candidates owing to its analogy to the well-established LiMn2O4 cathode for lithium-ion batteries, however its electrochemical mechanism in the presence of Zn ions in aqueous environment is unclear and still debated. In this work, we synthesised nanostructured ZMO thin films by Pulsed Laser Deposition (PLD) and we evaluated, through extensive characterization by microscopic, spectroscopic, and diffraction techniques, how the deposition and annealing conditions affect the film properties. The self-supported nature and the high degree of control down to the nanoscale make a thin film an ideal model system to study the electrochemistry of the material in aqueous solution and to emphasize the impact of the film properties on its electrochemical response. We highlighted the crucial role of the oxygen pressure in the modulation of the film porosity and the combined effect of deposition pressure and annealing temperature to produce a film with tailored properties in terms of morphology, crystallinity, and Zn stoichiometry. A complex redox mechanism involving multiple concurrent reactions and the formation of zinc hydroxide sulphate hydrate (ZHS) was reported, as well as the influence of the film porosity on the voltammetric behaviour of the film at higher scan rate. Our results confirm the intricate electrochemical mechanism of the ZMO material, which does not merely involve the Zn2+ insertion/extraction but also the crucial participation of Mn2+ from the electrolyte, and pave the way for the nanoscale design of engineered ZMO-based electrodes.

Understanding the key role of {100} exposed crystal facets on the electrochemistry of the spinel LiMn2O4 cathode

The exposed {111} facets truncated by a portion of {100} facets reduce the Mn2+ dissolved into the electrolyte and improve the cycling stability of the spinel LiMn2O4 cathode.

Structural and Electronic Properties of Cu2+ Doped LiMn2O4 Cathode Material for Rechargeable Lithium Ion Battery: A DFT Study

Spinel LiMn2O4 offers a potentially attractive alternative to the commercialized LiCoO2 because of its low cost, non-toxicity, good rate performance and superior safety, but experiences severe capacity fading as a result of Jahn-Teller cubic phase transition to unstable tetragonal phase especially when operated at elevated temperature (>55oC). Among the various techniques carried out to overcome these setbacks is doping with cations to raise the oxidation state of Mn thereby decreasing the amount of unstable Mn3+. This study focuses on the investigation of the structural and electronic properties of Cu2+ doped LiMn2O4 using ab-initio computational method. The structural properties of both un-doped LiMn2O4 and Cu2+ doped LiMn2O4 were collectively obtained using both generalized gradient approximation (GGA) employing pseudo-potentials, plane wave basis sets and XcryDen. From the electronic properties of undoped LiMn2O4, it was revealed that in LiMn2O4, only Mn3+ ions contribute to conduction, even though Mn3+ ions and Mn4+ ions exist together. Increasing the number of Mn3+ brings it a unique challenge of instability. Due to this instability, avoiding the Mn3+ state of manganese prevents Jahn-teller distortion, resulting in a reduced phase transition. Based on the results from the first-principles calculation of Cu2+ doped LiMn2O4, the Cu valence in doped spinel LiCu0.25Mn0.75O4 is Cu2+ at a fully lithiated state. When half of the Li ions are extracted, the Cu2+ ions oxidized to Cu3+ ions. Since Cu2+ is a di-valent element, the dopant act as electrochemically active centres for valence change, leaving two trivalent ions to only take on +4 oxidation states stably, thus increasing Mn-O bonding strength which ultimately suppressed Jahn-Teller distortions. However, previous studies show that Cu2+ substitution shrinks the lattice because the ionic radius of Cu2+ is smaller than that of the host Mn3+ ions, thereby the reversible capacity of Cu-doped spinel may be reduced as Cu ions can only provide one electron per ion.

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

Improved electrochemical performance of spinel LiMn2O4 derived from manganese-based metal–organic frameworks by organic ligands

The spinel LiMn2O4 cathode has received substantial attention from researchers owing to its high voltage plateau, eco-friendliness, and cost-effectiveness.

Enhanced high-temperature electrochemical properties of in situ carbon-coated truncated octahedral LiMn2O4 cathodes.

Truncated octahedral spinel LiMn2O4 was homogenously coated by amorphous carbon layer via chemical vapor deposition (CVD) using acetylene gas (C2H2) as carbon source to ease Mn dissolution to improve high-temperature performance, delivering a capacity retention of 92.9% after 1000 cycles at 5C at 50 °C.

A novel coral-like LiMn2O4 nanostructure as Li-ion battery cathode displaying stable energy-storage performance

Lithium-ion battery has been widely used in many fields; however, a good energy–density along with a high working voltage cathode is highly required. Here, a three-dimensional coral-like LiMn2O4 nanostructure is developed by annealing a precursor synthesized through a hydrothermal approach, which displays a stable electrochemical performance as Li-ion battery cathode. The coral-like LiMn2O4 cathode exhibits a capacity exceeds 118 mAh/g when cycling at 0.2C, and a Coulombic efficiency of 98.3%. When cycling at a relatively high rate of 0.5C, the electrochemical performance remains stable after 150 cycles. Moreover, good performances are achieved when cycling at different charge/discharge rates, which are ascribed to the biomimetic coral-like structure facilitates the transport of electrons and ions. The general preparation approach and the stable performance of the coral-like cathode would find broad applications for developing many other emerging energy-storage materials.

Electrochemical Performance and Conductivity of N-Doped Carbon Nanotubes Annealed under Various Temperatures as Cathode for Lithium-Ion Batteries

Nitrogen-doped carbon nanotubes (NCNTs) are obtained using a post-treatment method under different sintering temperatures. The catalysts can be removed from the Carbon Nanotubes (CNTs) within an acid treatment process. Then, the purified CNTs can be employed as a nitrogen doping basis. This research adds melamine as a nitrogen source during the sintering procedure under different temperatures to achieve NCNTs, which are applied to the cathodes. LiMn2O4 (LMO) cathode slurries are prepared using pristine CNTs and NCNTs samples as conductive additives. Coin cell lithium-ion batteries (LIBs) are fabricated using slurry samples. X-ray photoelectron spectroscopical analysis shows the nitrogen doping degree is up to 5 atom%, and graphitic-N nitrogen groups are the dominating species present on the NCNT’s surface while being treated at 800 °C. Graphitic-N nitrogen groups improve the conductivity and surface area of the NCNTs, which increases the rate capacity (106.8 mA h g−1 at 5 C) and cyclic retention (92.45% of initial capacity after 200 cycles at 5 C) of the lithium-ion batteries. The morphology of the NCNTs, the concentration of NCNTs elements, and the electrochemical performances of coin cell batteries are extensively discussed.

Enhanced high-rate cycling performance of LiMn2O4 cathode materials by coating nano-TiO2

Abstract LiMn2O4 has the advantages of low cost and no pollution, and is widely regarded as a large-scale lithium battery cathode material. However, the capacity decays rapidly, which seriously affects the application of LiMn2O4 cathode materials. Therefore, improving the cycling performance of LiMn2O4 is the focus of current research. LiMn2O4 precursors were prepared by chemical precipitation and the precursors were coated to prepare LiMn2O4/TiO2 composites. X-ray diffraction and scanning electron microscopy showed that LiMn2O4 had been successfully combined with TiO2. Electrode charge–discharge and electrochemical impedance tests showed that LiMn2O4/TiO2 had the best cycle performance at high rates. The initial discharge capacities of LiMn2O4/TiO2 reached 106.4 mAh·g−1 at 0.2 C. After 100 cycles, the 2 C capacity retention rates was 76.3 %, compared to only 66.5 % for pristine LiMn2O4. The improved electrochemical performance was attributed to the nanoscale oxides hindering the reaction between the electrolyte and the electrode, which effectively improved the stability of the material during high current charge and discharge.

Surface modification of Li3InCl6 provides superior electrochemical performance for LiMn2O4 cathode materials

LiMn2O4 (LMO) is the substance of choice for small and medium-sized energy storage materials in daily life. In this work, Li3InCl6 (LIC) is prepared on the surface of LiMn2O4 by hydrothermal method using InCl3 and LiCl as raw materials. This method stabilizes the LMO crystal structure by uniformly coating the LIC on the LMO surface and effectively maintains the morphology of LMO crystals during the cycling process. SEM and EDS analysis confirm the morphology and homogeneity of the synthesized material LIC on the LMO surface. The prepared material is put into a battery, and the charge-discharge test is carried out at 0.5 C and 1 C. The results show that the LIC surface-modified samples exhibit more than 6% higher cycling performance than the unmodified samples after long cycling.

Preparation and performance of Mg-doped spinel-structured LiMn2O4 cathode materials

The main work of this paper is to use the traditional high-temperature solid-state synthesis method to synthesize lithium manganese spinel cathode material and modify it by doping under optimized process parameters to improve its cycle performance. The doping of Mg2+ reduces the content of Mn3+ in the material. The material with Mg doping has higher structural stability and inhibits the Jahn-Teller and reduces the dissolution of Mn. LiMgxMn2−xO4 (x = 0, 0.02, 0.04, 0.06, 0.08) was synthesized by the traditional high-temperature solid-state method. The crystal structure and morphology of the synthesized powders were characterized by XRD, SEM, and FT-IR, respectively. The electrochemical performance of the battery was tested by CV, EIS, and long-term cycling. Among them, LiMg0.04Mn1.96O4 had the best cycling performance, the first discharge capacity of the material was 113.5 mAh·g−1. When it was cycled to 500 cycles at 0.1 C, still had the capacity of 92 mAh·g−1 with a capacity retention rate of 81.05%.

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.

Cost-effective recycling of spent LiMn2O4 cathode via a chemical lithiation strategy

The global lithium-ion battery recycling market is witnessing rapid growth considering the limited mineral resources and environmental sustainability. However, the conventional destructive recycling technology, mainly referred as pyrometallurgy and hydrometallurgy, cannot show obvious advantages in the recovering of low-value cathode (i.e. LiMn2O4, abbreviated as LMO), either judged from the perspective of environment or economy. Herein, we develop a facile and cost-effective chemical lithiation strategy to direct regenerate spent LMO cathode, and further investigate the efficacy of our technology for industrial-scale applications. Pyrene-Li compound, a highly reductive reagent capable of donating both e− and Li+, is adopted as the chemical lithiation agent to heal the Li deficiency in the degraded LMO cathode. Both the Li-deficient LMO model compounds prepared from acid delithiation method and the real degraded LMO harvested from commercial cells can be restored as original with comparable long-term stability as the pristine LMO cathode and even superior rate capability. Life-cycle analysis demonstrates that our approach is superior to conventional metallurgies because of its high economic profitability (2.78 $/kg cell) and minimal environmental impact (527 g GHG /kg cell), thus providing a brand new perspective for the recycling of low-value cathodes.

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.

First-principles Study and Experimental Preparation of LiMn2O4 Cathode Material Based on Spinel Structure

First-principles Study and Experimental Preparation of LiMn2O4 Cathode Material Based on Spinel Structure

New strategy for enhancing the electrochemical performance of LiMn2O4 cathode material

Despite spinel-structured LiMn2O4 (LMO) cathode material has been successfully commercialized for large scale energy storage, its cycling stability in practical applications still awaits for further improvement. Herein, we provided an effective strategy by adding phosphate in the preparation process, and this modification play a dual effect on LMO materials. Impressively, HRTEM indicated that Li3PO4 generated on the particle surface protects the LMO particles from electrolyte corrosions, while the fast ion conductor can effectively improve the lithium ion diffusion coefficient from 4.506 × 10−12 cm2 s−1 to 1.570 × 10−11 cm2 s−1. Meanwhile, the tetrahedral ion doped into the octahedrally transition metal oxide units, enhances the p-type carrier effect, resulting in the carrier density and Hall mobility are improved by a factor of ∼5 and ∼10, respectively. Electrochemical performance among the LMOP0.50 cathode with a high initial discharge capacity of ∼140 mA h g−1 at 0.1 C, and a capacity retention of 95.5 % after 500 cycles at 1 C. Consequently, the introduction of phosphate provides a new strategy for modifying LMO cathode material.

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.

Molecular Beam Epitaxy (MBE) Growth of Model Cathodes to Study Interfacial Ion Diffusion

AbstractLithium‐ion batteries (LIBs) have been the focus of research for decades owing to their superior energy storage potential and wide range of applications. However, long‐term stability issues still persist in LIB cathodes as the result of the formation of a solid electrolyte interface (SEI), structural transformations, or the loss of active cathode materials. In nanoscale cathodes, it is often impossible to isolate, let alone mitigate the causes of the observed capacity loss. Herein, a novel approach is presented to synthesizing LIB cathode model systems using thin‐film molecular beam epitaxy (MBE). Specifically, 100 nm thick LiMn2O4 (LMO) thin‐film cathodes are grown on SrRuO3/SrTiO3 (100) single‐crystal substrates and characterized in their pristine and cycled states. The pristine thin films exhibit the electro‐chemical cycling behavior and structural evolution previously seen in bulk LMO cathodes. The formation of surface‐layer rocksalt MnO and spinel Mn3O4 along with the mass‐loss associated with the corrosion of active Mn ions is also reported. It is, therefore, demonstrated that these MBE‐grown model systems can be used for detailed studies of their surface structures and the electrode/electrolyte interfacial evolution in LIB cathodes, leading to the development of materials for rechargeable batteries with higher capacity and better stability.

Self-Assembled Epitaxial Cathode-Electrolyte Nanocomposites for 3D Microbatteries.

The downscaling of electronic devices requires rechargeable microbatteries with enhanced energy and power densities. Here, we evaluate self-assembled vertically aligned nanocomposite (VAN) thin films as a platform to create high-performance three-dimensional (3D) microelectrodes. This study focuses on controlling the VAN formation to enable interface engineering between the LiMn2O4 cathode and the (Li,La)TiO3 solid electrolyte. Electrochemical analysis in a half cell against lithium metal showed the absence of sharp redox peaks due to the confinement in the electrode pillars at the nanoscale. The (100)-oriented VAN thin films showed better rate capability and stability during extensive cycling due to the better alignment to the Li-diffusion channels. However, an enhanced pseudocapacitive contribution was observed for the increased total surface area within the (110)-oriented VAN thin films. These results demonstrate for the first time the electrochemical behavior of cathode–electrolyte VANs for lithium-ion 3D microbatteries while pointing out the importance of control over the vertical interfaces.

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.