LiMn2O4 Microspheres Research Articles

The improved performance of spinel LiMn2O4 cathode with micro-nanostructured sphere-interconnected-tube morphology and surface orientation at extreme conditions for lithium-ion batteries

Recently, spinel-type LiMn2O4 (LMO) cathode has attracted great attention to mitigate manganese dissolution especially at elevated temperature. In this work, LMO with surface specific facets and different morphologies are successfully controlled synthesized via a facile solvothermal-lithiation method. It suggests that microspheres, micro-tubes and hybrid sphere-interconnected-tube microstructures with different surface lattice orientation using urea, oxalic acid and mixture of urea and oxalic acid as precipitants at solvothermal stage, respectively. Specifically, LMO microspheres (LMO-MS) display (111) facets and the micro-tubular LMO materials (LMO-MT) exhibit the high index lattice (311). It is more interesting is that hybrid sphere-interconnected-tube microstructures (LMO-MST) are clearly observed the densest (111) facets at the micro-spherical surface and a new (111) plane appearance on the surface of microtubes. LMO-MST demonstrates excellent cycling performance (84.3 % capacity retention after 1000 cycles at 10 C) and superior rate capability up to 10 C (124.2 mAh g−1 at 10 C). The electrochemical performances of LMO-MST cathodes are also investigated at elevated (55°C) and lower (-5°C) temperatures, under which LMO-MST still maintains optimal cycling stability. The superior electrochemical performance of LMO-MST cathodes can be attributed to the unique sphere-bridged-tube seamless outer structure and the preferentially exposed stable facets on the crystal surface.

Facile Controlled Synthesis of Spinel LiMn2O4 Porous Microspheres as Cathode Material for Lithium Ion Batteries.

Although the electrochemical properties of porous LiMn2O4 microspheres are usually improved compared to those of irregular LiMn2O4 particles, the effects of the different synthesis conditions on the preparation of the porous LiMn2O4 microspheres are rarely discussed in detail. In the present work, porous LiMn2O4 microspheres were successfully synthesized by using molten LiOH and porous Mn2O3 spheres as a template. Multiple factors were considered in the preparation process, including reagent concentration, pH, adding mode, heating time, etc. The morphology of the MnCO3 template was crucial for the preparation of porous LiMn2O4 microspheres and it was mainly affected by the concentration of reactants and the pH value of the solution during the precipitation process. During the lithiation of Mn2O3 microspheres, the heating temperature and the ratio between Mn2O3 and lithium salt were the most significant variables in terms of control over the morphology and purity of the LiMn2O4 microspheres. Furthermore, we demonstrated that the porous LiMn2O4 microspheres presented better rate capability and cyclability compared to commercial LiMn2O4 powder as cathode materials for lithium-ion batteries (LIBs). This study not only highlights the shape-controllable synthesis of LiMn2O4 microspheres as promising cathode materials, but also provides some useful guidance for the synthesis of porous LiMn2O4 microspheres and other LIB' electrode materials.

Porous LiMn2O4 Nano-Microspheres as Durable High Power Cathode Materials for Lithium Ion Batteries

Porous LiMn2O4 spheres was easily fabricated with MnCO3 spheres and MnO2 as precursors and characterized in terms of structure and performance as the cathode of a lithium ion battery. The presence of pores with the average size of about 50 nm throughout the whole LiMn2O4 microspheres was confirmed by scanning electron microscope (SEM) and N2 adsorption-desorption measurements. The electrochemical tests show that the synthesized product has smaller electrochemical polarization, faster Li-ion intercalation kinetics and higher electrochemical stability. It exhibits excellent rate capability and cyclic stability: delivering a reversible discharge capacity of 71 mA h g−1 at a 5 C rate and yielding a capacity retention of over 92% at a rate of 0.5 C after 100 cycles. The superior performance of the synthesized product is attributed to its special structure: porous secondary spheres particles consisting of primary single-crystalline nanoparticles. The nanoparticle reduces the path of Li-ion diffusion and increases the reaction sites for lithium insertion/extraction, the pores provide room to buffer the volume changes during charge-discharge and the single crystalline nanoparticle endows the spinel with the best stability. Taking the excellent electrochemical performance and facile synthesis into consideration, the presented porous LiMn2O4 spheres could be a competitive candidate cathode material for high-performance lithium-ion batteries.

Porous LiMn2O4 Microspheres With Different Pore Size: Preparation and Application as Cathode Materials for Lithium Ion Batteries

Three types of LiMn2O4 (LMO) microspheres with different pore size are prepared by a facile method, using porous MnCO3–MnO2 and Mn2O3 microspheres as the self-supporting template, for lithium ion batteries (LIBs) cathode material. Briefly, Mn2O3 and MnO2 microspheres are heated in air at 600 °C for 10 h to synthesize porous Mn2O3 spheres. Then the mixture of as-prepared spherical Mn2O3 and LiNO3 is calcined to obtain the LMOs. The morphology and structure of LMOs are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen adsorption/desorption analyses. The result shows that the maximum pore diameters of LMOs are 17 nm, 19 nm, and 11 nm, respectively. All LMOs microspheres are composed of similar sized nanoparticles; however, the surface of these microspheres is strewed with dense tinier pores or sparse larger pores. Generally, the nanoparticles will reduce the path of Li+ ion diffusion and increases the reaction sites for lithium insertion/extraction. Moreover, the pores can provide buffer spaces for the volume changes during charge–discharge process. The electrochemical performances of LMOs are investigated and LMO2 exhibits extremely good electrochemical behavior, especially the rate capability. The as-prepared LMO2 delivers a discharge capacity of 124.3 mAh g−1 at 0.5 C, retaining 79.6 mAh g−1 even at 5 C. The LMO2 sample also shows good capacity retention of 96.9% after 100 cycles at 0.5 C.

The enhancement of rate and cycle performance of LiMn2O4 at elevated temperatures by the synergistic roles of porous structure and dual-cation doping

Spinel LiMn2O4-based cathode material has been successfully commercialized for power lithium ion batteries for large-scale applications in pure electric vehicles. However, pure LiMn2O4 suffers from poor rate performance and fast capacity fading especially at elevated temperatures derived from Mn dissolution and structural distortion. Herein, a study on the rate and cycle performance of single/double-cation doped porous LiMn2O4 microspheres, which was prepared by an easy method using porous MnCO3 microspheres as a self-supporting template, was performed. The as-synthesized porous Li1.02Co0.05Mn1.90Li0.05O4 (LMO-S4) microspheres constructed with nanometer-sized primary particles show an obvious enhancement of cyclability over other LiMn2O4-based materials such as Li1.02Mn2O4 (LMO-S1), Li1.02Mn1.95Li0.05O4 (LMO-S2) and Li1.02Co0.05Mn1.95O4 (LMO-S3), especially at an elevated temperature (55 °C). The obtained LMO-S4/lithium half cells deliver capacities of 113.1 and 109.0 mAh g−1 at 1.0 and 5 C, respectively, with the corresponding capacity retentions of 88.9 and 90.2% for up to 1000 cycles. Meanwhile, it can deliver an initial capacity of 114.0 mAh g−1 at 5 C with a capacity retention of 80.1% after 1000 cycles at 55 °C. Furthermore, it displays superior rate performance and cycle performance at 0 °C with a specific capacity of 106 mAh g−1, and the capacity retention is 79.6% after 1000 cycles at 5 C. These results reveal that a dual-doping strategy and porous structure design play synergistic roles in the preparation of high performance LiMn2O4-based spinel cathode material. The cation co-doped strategy can maintain the crystal structural stability and provide interfacial stability while preserving fast Li+ diffusion during the long-time cycling at elevated temperatures. Furthermore, the porous structure favors fast Li+ intercalation/deintercalation kinetics by allowing electrolyte insertion through the nanoparticles during the reversible electrochemical process. Lithium and cobalt co-doped LiMn2O4 with a nominal composition of Li1.02Co0.05Mn1.90Li0.05O4 exhibits an obviously improved cycle performance at high temperature than that of single-doped LiMn2O4.

LiMn2O4 microspheres as high-performance cathode materials for Li-ion batteries

Spinel LiMn2O4 microspheres were prepared by lithiating MnCO3 solid microspheres and MnO2 hollow microspheres, respectively. Li2CO3 was used as lithium source. The spinel LiMn2O4 microspheres samples annealed at different temperatures were characterized by XRD, SEM, and galvanostatic charge/discharge profile measurement. The LiMn2O4 microspheres show an initial discharge capacity reaches 128 mAh/g at 1 C, more than 120 mAh/g of capacity is retained after 80 cycles and the best cycling stability. These results indicate that the LiMn2O4 microspheres could be a promising cathode material for lithium ion batteries.

High capacitance LiMn2O4 microspheres with different microstructures as cathode material for aqueous asymmetric supercapacitors

Asymmetric supercapacitors (ASCS) with a battery-type electrode and a capacitor-type electrode have been regarded as the most promising energy-storage devices with high-energy and high-power densities. In this paper, the porous and hollow LiMn2O4 microspheres were prepared using MnCO3 microspheres as template and subsequently an ASCS with the as-prepared LiMn2O4 as cathode and activated carbon (AC) as anode in Li2SO4 aqueous electrolyte (designated by AC//LiMn2O4 ASCS) was assembled and investigated electrochemically. The results indicate that the porous LiMn2O4 exhibits a higher reversible capacity and rate capability compared to hollow LiMn2O4 microspheres, and delivers a specific capacitance of 536 F g−1 at 1 mV s−1. The assembled AC//porous LiMn2O4 ASCS presents a high energy density of 33.12 Wh kg−1 at the power density of 90 W kg−1. All these might be attributed to the unique microstructure of the as-prepared porous LiMn2O4 microspheres.

Microemulsion Concentration in Preparation of LiMn2O4 Submicron Spherical Particles as Cathode Materials for Highly Reversible Lithium‐Ion Batteries

AbstractSpinel LiMn2O4 is one of the most important cathode materials but it still suffers from rapid capacity degradation during electrochemical cycling. Beside surface coating to improve the electrochemical performances, controlling the bulk morphology of LiMn2O4 (LMO) is another effective strategy. In this work, porous LiMn2O4 microspheres composed of numerous primary nanoparticles are synthesized by micro‐emulsion and co‐precipitation methods. The porous structure and the primary nanoparticles size of LiMn2O4 are effected by the concentration of micro‐emulsion and the precursor of Mn2+. The well‐established porous LiMn2O4 microspheres with abundant ionic channels and good contact with electrolyte endow the spinel a remarkable electrochemical performance. After 300 cycles, 0.50 M‐LMO sample presents excellent reversible capacity of 112.8 mAh g−1 at 0.5 C rate. After 1000 cycles, 0.50 M‐LMO sample presents the highest capacity of 97.9 mAh g−1 and remains 54.2 mAh g−1 at the current rate of 10 C. The porous spherical structure of cathode materials is essential to improve the rate performance due to the good contact between the active material and electrolyte.

Controllable preparation and superior rate performance of spinel LiMn2O4 hollow microspheres as cathode material for lithium-ion batteries

Spinel LiMn2O4 microspheres and hollow microspheres with adjustable wall thickness have been prepared using controllable oxidation of MnCO3 microspheres precursors and following solid reactions with lithium salts. Scanning electron microscopy (SEM) investigations demonstrate that the microsphere morphology and hollow structure of precursors are inherited. The effect of hollow structure properties of as-prepared LiMn2O4 on their performance as cathode materials for lithium-ion batteries has been studied. Electrochemical performance tests show that LiMn2O4 hollow microspheres with small wall thickness exhibit both superior rate capability and better cycle performance than LiMn2O4 solid microspheres and LiMn2O4 hollow microspheres with thick wall. The LiMn2O4 hollow microspheres with thin wall have discharge capacity of 132.7 mA·h·g-1 at C/10 (14.8 mA·g-1) in the first cycle, 94.1% capacity retention at C/10 after 40 cycles and discharge capacity of 116.5 mAh·g-1 at a high rate of 5C. The apparent lithium-ion diffusion coefficient (Dapp) of as-prepared LiMn2O4 determined by capacity intermittent titration technique (CITT) varies from 10-11 to 10-8.5 cm2·s-1 showing a regular “W” shape curve plotted with test voltages. The Dapp of LiMn2O4 hollow microspheres with thin wall has the largest value among all the prepared samples. Both the superior rate capability and cycle stability of LiMn2O4 hollow microspheres with thin wall can be ascribed to the facile ion diffusion in the hollow structures and the robust of hollow structures during repeated cycling.

Study of Aqueous Lithium Ion Batteries Utilizing Spinel Compound Anodes

1. Introduction – Secondary Li ion batteries, regarded as the current benchmark for new battery technologies, are under extensive development throughout the world [1]. However, their requirement that organic electrolytes be used limits the rate capacity and specific power the cell can achieve and present several safety hazards and cost limitations that limit their application in large-scale storage systems [1, 2]. Here, aqueous Li ion cells utilizing LiMn2O4 spinel compound anodes is investigated, due to its ample capacity, cycling stability and high rate capability [3].2. Fabrication procedures – LiMn2O4 (LMO) anode is fabricated by solid state reaction of 5 mmol Li2CO3 and 10 mmol Mn2O3 at 750 °C for 20 hrs. Li2Mn4O9 cathode is fabricated by solid state reaction of 10 mmol LiOH·H2O and 20 mmol MnCO3 at 380 °C for 24 hrs. LiMn2O4 solid microspheres were prepared by calcination of LiOH·H2O and MnCO3 microspheres at 650 °C for 3 hrs in air. MnCO3 solid microspheres were prepared as follows: 1 mmol MnSO4·H2O and 1 mmol NaHCO3 were dissolved separately in 70 ml of distilled water. 7 ml of ethanol was added to the MnSO4 solution under stirring. Direct mixing of the NaHCO3 and MnSO4 solutions is done, and precipitate is allowed to form overnight. MnCO3 microspheres were obtained from multiple centrifugation and washing cycles. Obtained product was allowed to dry overnight at 100 °C in air. Activated carbon (AC, Kureha BAC) is utilized as received.3. Experimental setup and results – XRD spectra of the solid state LiMn2O4 anode (LMO¬_SS) and LiMn2O4 solid microspheres (LMO_Sμ) are shown in Figure 1(a). SEM image of the LMO solid microspheres is shown in Figure 1(b). Cycling performance of LMO_SS vs. Li2Mn4O9 in 6M LiCl (pH 12, 0.01 M LiOH) is shown in Figure 2. 1st discharge capacities and charge voltage plateaus of cells utilizing LMO_SS vs. AC in 6M LiCl with varying pH is shown in Figure 3. Charge currents of 1.5 mA cm-2 and discharge currents of 0.25 mA cm-2 are used for all cell tests. 4. Conclusions – An initial decrease in discharge capacity of the LiMn2O4 and Li2Mn4O9 cell is observed from the 1st to 20th discharge cycle. The discharge capacity of the cell is observed to asymptotically approach 60 mAh/g by the 100th cycle. Discharge voltage and capacity of the LMO and AC cell is observed to be greatly dependent on electrolyte pH. A voltage plateau during is observed during charging that did not contribute to cell discharge capacity. Future work aims to investigate the processes occurring at the anode during the observed charge voltage plateau as well as the change in charge transfer kinetics and cell capacity when employing both solid and hollow LiMn2O4 microspheres as the active anode. Due to the dissolution tendencies of Mn in aqueous electrolyte, methods of increasing cell cycling stability are also of interest.5. References – [1] G.X. Wang, S. Zhong, D.H. Bradhurst, S.X. Dou, H.K. Liu, Journal of Power Sources, 74 (1998) 198-201.[2] X. Zeng, Q. Liu, M. Chen, L. Leng, T. Shu, L. Du, H. Song, S. Liao, Electrochimica Acta, 177 (2015) 277-282.[3] W. Tang, S. Tian, L.L. Liu, L. Li, H.P. Zhang, Y.B. Yue, Y. Bai, Y.P. Wu, K. Zhu, Electrochemistry Communications, 13 (2011) 205-208. Figure 1

Template synthesis and lithium storage performances of hollow spherical LiMn2O4 cathode materials

Hollow-structured LiMn2O4 microspheres were successfully prepared via a template strategy, in which xMnCO3·yCaCO3 spheres, obtained by a co-precipitation method, served as hard templates for synthesizing hollow spherical LiMn2O4 cathode materials. The effects of Ca2+/Mn2+ ratio of raw materials on the morphology and electrochemical performances of the resultant LiMn2O4 were investigated. SEM results indicated that the LiMn2O4 sample prepared at a Ca2+/Mn2+ ratio of 3:2 exhibited a well formed hollow spherical morphology with minor collapse in the structure, thus enabling larger capacity (125mAhg−1 at 1C), higher rate capability (94.4mAhg−1 at 5C), and better cycling stability (90% capacity retention after 100 cycles) compared to other LiMn2O4 samples. This template method provides a viable and inexpensive route to mass production of LiMn2O4-based cathode materials for lithium-ion batteries.

LiMn2O4/graphene composites as cathodes with enhanced electrochemical performance for lithium-ion capacitors

The LiMn2O4microspheres (LMO-MSs)/graphene nanosheets (GNSs) composites have been synthesized using γ-MnO2microspheres as precursor.

Facile fabrication of LiMn2O4 microspheres from multi-shell MnO2 for high-performance lithium-ion batteries

A facile and convenient method is proposed to fabricate the LiMn2O4 microspheres from multi-shell MnO2. Comparing to the LiMn2O4 synthesized from commercial electrolytic MnO2 (EMD), the LiMn2O4 microspheres synthesized in this work exhibit a close-to-theory specific capacity of 145.9mAh/g at 0.2C, while the LiMn2O4 from commercial MnO2 only shows a value of 105.3mAh/g under the same testing conditions. LiMn2O4 microspheres also exhibit an excellent rate performance: 131.8 and 113.3mAh/g at 5 and 10C, respectively. This facile and convenient method to prepare LiMn2O4 microspheres provides a new way to fabricate lithium manganate cathode materials with high specific capacity and rate performance.

Synergistic effect for the preparation of LiMn2O4microspheres with high electrochemical performance

Under the synergistic promotion of chemical reactions, MnO2 microspheres are successfully prepared using MnCO3 precursor as self-template, with maximum use of the raw materials, and are then converted into spinel LiMn2O4 microspheres via a solid-state reaction. When applied as cathode materials for rechargeable lithium-ion batteries, the LiMn2O4 microspheres deliver a discharge capacity of 133.2 mA h g−1 and 109.8 mA h g−1 at 0.1 C and 10 C rates, respectively. More than 91.3% of the initial storage capacity is maintained after 1000 cycles at a 1 C charge and 10 C discharge rate. Furthermore, even when cycled at elevated temperature (55 °C) at a 1 C charge and 10 C discharge rate, this material showes 86.2% capacity retention after 100 cycles, which reveals a high reversible capacity, superior rate capability and excellent cycling stability under high rates both at room temperature and high temperature. The performance is comparable to the best results shown in the literature so far. This structured LiMn2O4 microspheres in the present work are very promising for large-scale commercialization of high-power lithium ion batteries.

Hierarchical LiMn2O4 microspheres for high rate lithium ion batteries, and direct electrochemistry and electrocatalysis

Hierarchical LiMn2O4 microspheres were prepared using urchin-like α-MnO2 as a self-sacrificial template. As the cathode material for lithium ion batteries, the electrochemical properties were characterized by cyclic voltammetry and charge/discharge experiments. The results indicated that the LiMn2O4 microspheres had high discharge capacity and excellent cycle stability. Furthermore, a new electrochemical biosensor was constructed by immobilization of bovine myoglobin (Mb) and LiMn2O4 in a thin film of chitosan (CTS) on the surface of carbon ionic liquid electrode (CILE). Electrochemical behaviors of Mb entrapped in the film were investigated by cyclic voltammetry. A pair of well-defined redox peaks appears, which indicates a fast electron transfer rate of Mb with the underlying CILE. The electron transfer coefficient and electron transfer rate constant of Mb were calculated to be 0.47 and 1.04s−1, respectively. The Mb modified electrode showed good electrocatalytic ability toward the reduction of trichloroacetic acid (TCA) with a detection limit of 0.16mmolL−1 (3σ).

Porous LiMn2O4 microspheres as durable high power cathode materials for lithium ion batteries

Porous LiMn2O4 microspheres, which are constructed with nanometer-sized primary particles, have been synthesized by a facile method using porous MnCO3 microspheres as a self-supporting template. The LiMn2O4 microspheres were characterized by XRD, SEM and HR-TEM. The as-synthesized porous LiMn2O4 microspheres exhibit high rate capability and long-term cyclability as cathode materials for lithium ion batteries, with the specific discharge capacity of 119, 107 and 98 mA h g−1 and the corresponding capacity retention of 82, 91 and 80% for up to 500 cycles at 2, 10 and 20 C, respectively. The high rate performance and good cyclability are believed to result from the porous structure, reasonable primary particle size and high crystallinity of the obtained material, which favor fast Li intercalation/deintercalation kinetics by allowing electrolyte insertion through the nanoparticles and high structural stability during the reversible electrochemical process. The high level of Mn4+ concentration on the surface of the sample can alleviate the Jahn–Teller transition, which was triggered normally by the equal amounts of Mn4+/Mn3+ concentration on the surface of the LiMn2O4 cathode material. This good example offering extended cycle life at 20 C rate for the LiMn2O4 microspheres indicates their promising application as cathode materials for high performance LIBs.

Designed synthesis of LiMn2O4microspheres with adjustable hollow structures for lithium-ion battery applications

Two types of LiMn2O4 microspheres with similar sizes but adjustable hollow structures have been synthesized using a new and simple approach. Their performance as cathode materials for lithium ion battery applications has been studied and correlated with the hollow structural parameters. Through a solid state reaction between LiOH and mesoporous MnO2 obtained by the complete decomposition of MnCO3, LiMn2O4 hollow spheres with a robust wall and small cavity size are prepared (LiMn2O4-A). The fusion of the mesopores and the Kirkendall effect during the lithiation process are responsible for the hollow interior formation. In another approach through partial decomposition and selective etching, LiMn2O4 hollow spheres with thin walls are prepared (LiMn2O4-B). It is demonstrated that LiMn2O4-A shows larger capacity, superior rate capability, and better cycling stability compared to LiMn2O4-B. The former exhibits an initial discharge capacity of ∼120 mA h g−1, maintains 96.6% of the initial capacity after 105 cycles at 1 C and ∼90% of the capacity at 0.1 C when discharged at 5 C.

Facile synthesis of porous LiMn2O4 spheres as cathode materials for high-power lithium ion batteries

A facile topochemical route has been developed to synthesize porous LiMn2O4 spheres by using molten LiOH and porous Mn2O3 spheres as a template. The presence of pores with the average size of about 45 nm throughout the whole LiMn2O4 microspheres was confirmed by transmission electron microscope (TEM) and N2 adsorption–desorption measurements. When applied as cathode materials for rechargeable lithium-ion batteries, the porous sphere LiMn2O4 revealed stable high-rate capability. The discharge capacity is 83 mAh g−1 at 20 C rate, and it shows a good capacity retention after cycling at constantly changing discharge rate. Taking the excellent electrochemical performance and facile synthesis into consideration, the presented porous LiMn2O4 spheres could be a competitive candidate cathode material for high-performance lithium-ion batteries.

Synthesis of spinel LiMn2O4 microspheres with durable high rate capability

Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates, combined with the calcinations of LiNO3 at 700 °C for 8 h. The spherical MnCO3 precursors were obtained from the control of the crystallizing process of Mn2+ ions and NH4HCO3 in aqueous solution. The effects of the mole ratio of the raw materials, reaction time, and reaction temperature on the morphology and yield of the MnCO3 were investigated. The as-synthesized MnCO3 and LiMn2O4 microspheres were characterized by powder X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Galvanostatic charge/discharge tests indicate that the spinel LiMn2O4 microspheres deliver a discharge capacity of 90 mA·h/g at 10C rate show good capacity retention capability (75% of their initial capacity after 800 cycles at 10C rate). The durable high rate capability suggests that the as-synthesized LiMn2O4 microspheres are promising cathode materials for high power lithium ion batteries.

Synthesis and electrochemical properties of LiMn2O4 and LiCoO2-coated LiMn2O4 cathode materials

The synthesis of spinel LiMn2O4 material by a spherical MnO2 precursor route is reported in this paper. Hydrothermal and solid-state reactions were adopted to investigate the effects of synthetic methods on the morphologies and electrochemical characteristics of the LiMn2O4 products, respectively. LiCoO2-coated LiMn2O4 microspheres were also prepared by a sol–gel route based on the as-prepared LiMn2O4 microspheres. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrum (EDX), and inductively-coupled plasma emission spectrograph (ICP-ES). The results show that LiMn2O4 octahedrons can be obtained under hydrothermal conditions while LiMn2O4 microspheres can be prepared by the solid-state reaction. Electrochemical characterization reveals that the resulting LiMn2O4 microspheres and LiCoO2-coated LiMn2O4 microspheres display much better cycling properties than those of LiMn2O4 octahedrons.