Commercial Electrolytic Manganese Dioxide Research Articles

Rechargeable Manganese Dioxide||Hard Carbon Lithium Batteries in an Ether Electrolyte

Earth-abundant, cost-effective electrode materials are essential for sustainable rechargeable batteries and global decarbonization. Manganese dioxide (MnO2) and hard carbon both exhibit high structural and chemical tunability, making them excellent electrode candidates for batteries. Herein, we elucidate the impact of electrolytes on the cycling performance of commercial electrolytic manganese dioxide in Li chemistry. We leverage synchrotron X-ray analysis to discern the chemical state and local structural characteristics of Mn during cycling, as well as to quantify the Mn deposition on the counter electrode. By using an ether-based electrolyte instead of conventional carbonate electrolytes, we circumvent the formation of a surface Mn(II)-layer and Mn dissolution from LixMnO2. Consequently, we achieved an impressive ∼100% capacity retention for MnO2 after 300 cycles at C/3. To create a lithium metal-lean full cell, we introduce hard carbon as the anode which is compatible with ether-based electrolytes. Commercial hard carbon delivers a specific capacity of ∼230 mAh g−1 at 0.1 A g−1 without plateau, indicating a surface-adsorption mechanism. The resulting manganese dioxide||hard carbon full cell exhibits stable cycling and high Coulombic efficiency. Our research provides a promising solution to develop cost-effective, scalable, and safe energy storage solutions using widely available manganese oxide and hard carbon materials.

Facile Electrode Additive Stabilizes Structure of Electrolytic MnO2 for Mild Aqueous Rechargeable Zinc-Ion Battery

Rechargeable aqueous zinc-ion batteries (ZIBs) have attracted much attention recently due to the high abundance, low cost, high theoretical capacity up to 820 mAh g-1 with multi-valent charge carrier, and compatibility with aqueous electrolyte of the zinc anode.[1] Especially, the introduction of neutral or mild acidic electrolyte greatly improves the reversibility of zinc anode compared to conventional alkaline ZIBs.[2] Among all the cathode candidates, MnO2 is most attractive due to its relatively high energy density, low toxicity and low cost.[3] However, MnO2 electrode suffers from capacity fading during cycling mainly due to Mn dissolution and structural change. The addition of Mn2+ into the mild acidic electrolyte is a common method to suppress Mn dissolution.[4] Other strategies like structural design and surface coatings are also developed to suppress Mn dissolution.[5, 6] Though the cycle performance still cannot meet the demand of application, as the irreversible formation of inactive ZnMn2O4 during cycles still requires to be tackled.Here, we proposed Bi2O3 as a facile electrode additive in the electrode to suppress ZnMn2O4 formation and improve the cyclability of commercial electrolytic manganese dioxide (EMD). XRD, in-situ pH measurements and ICP tests suggest that inactive ZnMn2O4 is formed upon cycling due to the interaction between MnO2 and zincate ions in the electrolyte from localized increase in pH, and Bi2O3 dissolves into the electrolyte in the presence of zincate ions and forms a complex with the zincate ions to suppress the reaction pathway. A high capacity of 269 mAh g-1 is maintained at 100 mA g-1 after 50 cycles with a capacity retention of 91.5% when EMD with 10 wt% of Bi2O3 is tested in ZnSO4 electrolyte without Mn2+ additive. Combining both Bi2O3 electrode additive and Mn2+ electrolyte additive, EMD can maintain a stable capacity of 190 mAh g-1 for 1000 cycles at 1000 mA g-1 (about 3.3C). More characterizations are underway to further understand the role of Bi2O3 and the results will be shown during the meeting.Reference:[1] B. Tang, L. Shan, S. Liang, J. Zhou, Issues and opportunities facing aqueous zinc-ion batteries, Energy & Environmental Science, 12 (2019) 3288-3304.[2] J. Hao, X. Li, X. Zeng, D. Li, J. Mao, Z. Guo, Deeply understanding the Zn anode behaviour and corresponding improvement strategies in different aqueous Zn-based batteries, Energy & Environmental Science, 13 (2020) 3917-3949.[3] N. Zhang, X. Chen, M. Yu, Z. Niu, F. Cheng, J. Chen, Materials chemistry for rechargeable zinc-ion batteries, Chemical Society Reviews, 49 (2020) 4203-4219.[4] H. Pan, Y. Shao, P. Yan, Y. Cheng, K.S. Han, Z. Nie, C. Wang, J. Yang, X. Li, P. Bhattacharya, Reversible aqueous zinc/manganese oxide energy storage from conversion reactions, Nature Energy, 1 (2016) 1-7.[5] J. Huang, Z. Wang, M. Hou, X. Dong, Y. Liu, Y. Wang, Y. Xia, Polyaniline-intercalated manganese dioxide nanolayers as a high-performance cathode material for an aqueous zinc-ion battery, Nature communications, 9 (2018) 1-8.[6] B. Wu, G. Zhang, M. Yan, T. Xiong, P. He, L. He, X. Xu, L. Mai, Graphene scroll‐coated α‐MnO2 nanowires as high‐performance cathode materials for aqueous Zn‐ion battery, Small, 14 (2018) 1703850. Figure 1

PH-Controlled Electrolysis of Electrolytic Manganese Dioxide (EMD) for Improved Cycle Life of Rechargeable MnO2/Zn Batteries

A systematic study of the effect of acid concentration (0.5–5 M H2SO4) on the electrolysis of electrolytic manganese dioxide (EMD or γ-MnO2) has been performed. All the samples were characterized for their phase and crystallinity, their structural water, the pyrolusitic-to-ramsdellite ratio, BET surface area, pore size range; and were examined for their electrochemical performance. Concentration of the electrolysis acid affects the structural water content and the pyrolusitic-to-ramsdellite ratio of the γ-MnO2 phase as well as the surface area and pore size. The best cycling performance was achieved for the samples prepared with an electrolysis bath containing an acid concentration of about 2 M H2SO4. Electrochemical performance over 100 cycles of the EMD prepared in 2 M H2SO4 has shown higher energy efficiency and improved longer term cycling performance compared to commercial EMD products. Post-mortem analysis of the cycled EMD samples show partial loss of the EMD phase, loss of water content, and growth of irreversible manganese dioxide phases.

Electrosynthesis and characterization of nanostructured MnO2 deposited on stainless steel electrode: a comparative study with commercial EMD

The nanostructured MnO2 powder was successfully synthesized by electrodeposition on stainless steel (SS) substrate from hot 0.3 M MnSO4·H2O aqueous solution with pH value adjusted to 2. The electrochemical behavior of synthesized MnO2 was compared to that of the commercial electrolytic manganese dioxide (EMD). The investigation was conducted using a new cell which is manufactured in our laboratory. This gave us the possibility to present a new contribution and an improvement in the study of MnO2 electrochemical behavior. The analysis of the synthesized MnO2 and EMD powders by different techniques: FEG-SEM, EDS, TEM, XRD, and BET revealed the presence of electrodeposited nanostructured γ-MnO2 with high specific surface area of 139.59 m2 g−1 for the nanostructured MnO2 and 46.60 m2 g−1 for EMD. The electrochemical study of these powders conducted by linear voltammetry, electrochemical impedance spectroscopy (EIS) measurements, and Zn/MnO2 battery tests in 0.1 M NH4Cl electrolyte showed that the performance of the synthesized nanostructured MnO2 powder was higher than that of the commercial EMD powder.

PH-Controlled Electrolysis of Electrolytic Manganese Dioxide (EMD) for Improved Rechargeable MnO2/Zn Batteries

Alkaline batteries with the MnO2/Zn chemistry offer a number of advantages over other aqueous batteries (e.g., lead acid) including: a) high energy density, b) lower cost, and c) longer shelf life. The main active material used in the cathode electrode of these batteries is manganese dioxide, which has a low production cost, low toxicity, high specific capacity, low self-drain rate, and is abundant in nature. However, alkaline batteries cannot be easily recharged due to the rapid capacity loss and low energy efficiency of the MnO2 product used. An approach to improving the rechargeability of alkaline batteries may be synthesizing higher quality and/or modified manganese dioxide material. Manganese dioxide is a highly versatile substance that can grow into various crystal structures with different synthesis methods and be used in applications such as lithium-ion batteries, water oxidation electrocatalysts, etc. The preferred manganese dioxide used in alkaline batteries is electrolytic manganese dioxide (EMD) with a crystal structure which is an intergrowth of two different phases, pyrolusite and ramsdellite, which consist of arrays of MnO6 octahedra in 1 x 1 and 1 x 2 tunnels, respectively. The tunnels in the structure allow for the intercalation/deintercalation of protons during the discharge and charge processes. The EMD structure also contains protons (Ruetschi and Coleman protons) in the form of OH- complexes (also referred to as structural water) which provide a proton bridge, thus increasing the rate of proton diffusion into the lattice structure. The structural water content of EMD is an important parameter for the overall performance and has not been thoroughly reported before. Electrodeposition of EMD relies on the oxidation of Mn2+ to Mn4+ on a stable, conductive metal anode (e.g. titanium, nickel, etc.) in an acidic environment (typically H2SO4) which determines the water content. The EMD samples were electrodeposited by electrolysis of MnSO4 onto a titanium anode (4 cm × 14 cm × 2 mm) in an electrolyte solution containing 1.25 M MnSO4 and H2SO4 ranging from 0.5-5 M of H2SO4 at 95 oC using a current density of 115 A m-2. Electrosynthesis was performed for a period of 15 hours, thereafter, the deposits were chipped, grounded, washed, and filtered. The samples were then characterized using Thermogravemetric Analysis (TGA), X-Ray Diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area analysis techniques. Electrochemical properties of the EMD sample were examined with flat-plate cells using a zinc anode and a 9M KOH electrolyte solution and were cycled at a rate of C/10. Electrochemical impedance spectroscopy analysis was performed using a half-cell set-up using a nickel mesh as the counter electrode and an Hg/HgO reference electrode. The EMD samples synthesized with a manganese salt to acid ratio of 1.25:2 show a structural water content and surface area which are nearly twice that of the commercially available EMD products. Additionally, the ramsdellite fraction of the EMD samples increases by about 40%. EMD samples prepared in 2M acid solution exhibit improved cycling performance (see Figure) and energy efficiency when compared to commercial EMD products. The increase in water content is one possible explanation for the enhancement of the protonic conductivity of the in-house EMD as well as its improved physical characteristics. Synthesis and characterization of EMD samples and their electrochemical results will be presented Figure 1

Electrochemical properties of Bi-Ni and Bi-Ni-Mn composite-coated electrolytic manganese dioxide

The Bi-Ni and Bi-Ni-Mn composite is separately coated on the surface of commercial electrolytic manganese dioxide (EMD) by using a simple chemical precipitation/oxidation method. The results of X-ray diffraction show that a structure of γ-MnO2 is kept for all the coated EMD, but the intensity of their diffraction peaks is lower than uncoated one. Both the Bi0.5-Ni0.5 and Bi0.35-Ni0.35-Mn0.3 composite benefits the discharge capacity and high-power performance of the EMD electrodes. On the other hand, the results of scanning electron microscopy and energy dispersive spectroscopy confirm the more uniform distribution of the Bi0.15-Ni0.55-Mn0.3 composite on the surface of EMD than the Bi0.5-Ni0.5 one, thereby resulting in better cyclability of the electrodes. After 50 cycles at a 1C rate, the capacity retention rate of the Bi0.15-Ni0.55-Mn0.3 composite-coated electrode reaches to 80%, which is far larger than the un-coated (49%) and the Bi0.5-Ni0.5 composite-coated (63%) one.

Manganese oxide/graphene oxide composites for high-energy aqueous asymmetric electrochemical capacitors

A high-energy aqueous asymmetric electrochemical capacitor was developed using manganese dioxide (α-MnO2)/graphene oxide (GO) nanocomposites. The nanostructured α-MnO2 was prepared from micron-sized commercial electrolytic manganese dioxide (EMD) via a hydrothermal reaction in the presence and absence of sodium dodecylsulphate (SDS), α-MnO2(SDS) and α-MnO2, respectively. Unlike the as-prepared α-MnO2, the presence of SDS during the hydrothermal reaction conferred different morphologies on the intermediate precursors for the α-MnO2(SDS). Also, the XRD patterns showed that the α-MnO2(SDS) are more crystalline than the as-prepared α-MnO2. The superior electrochemical performance of the α-MnO2(SDS)/GO composite (280Fg−1, 35Whkg−1, and 7.5kWkg−1 at 0.5Ag−1) coupled with excellent long cycle life clearly indicates that this electrode system has the potential of being developed as an efficient aqueous asymmetric electrochemical capacitor. The high performance of the α-MnO2(SDS)/GO composite was interpreted in terms of the enhanced crystallinity of the α-MnO2(SDS). Interestingly, the electrochemical performance is comparable to or even better than those reported for the more conductive graphene/MnO2 composites.

Tuning Electrolytic Manganese Dioxide for a High-Voltage Aqueous Asymmetric Electrochemical Capacitor

An aqueous asymmetric electrochemical capacitor was developed using manganese dioxide / multiwalled carbon nanotubes (MnO2/MWMWCNT) nanocomposites. The nanostructured MnO2 was generated from micron-sized commercial electrolytic manganese dioxide (EMD) via a hydrothermal reaction, with the addition of the surfactant sodium dodecylsulphate (SDS), and acid treatment. The capacitance of the nano-sized MnO2 was improved. The MnO2/MWCNT hybrid exhibited excellent specific capacitance (170 F g-1), energy density (18 Wh kg-1), power density (4 kW kg-1), satisfactory cycle life, and short response time.

Controllable syntheses of α- and δ-MnO2 as cathode catalysts for zinc-air battery

Four MnO2 samples were synthesized through a simple reaction of KMnO4 with high-purity graphite in different concentrations of sulfuric acid at low temperature. Their morphology, crystal structure and performance as cathode catalysts of zinc-air battery were investigated with X-ray diffraction (XRD), Fourier transformation infrared spectrometer (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) and electrochemical tests. It is found that the crystal structure and the morphology of the synthesized samples depend on the sulfuric acid concentration. The synthesized samples have large specific surface area and exhibit excellent performance compared to the commercial electrolytic manganese dioxide (γ-MnO2). Two varieties of manganese dioxides, δ-MnO2 (the as-prepared samples a and b) and α-MnO2 (the as-prepared sample c and d), were obtained when using low and high sulfuric acid concentration, respectively. Higher sulfuric acid concentration favors the agglomeration of the particles. The specific surface area of samples a, b, c, d, and γ-MnO2 is 83.2, 81.1, 88.5, 86.8, and 43.5m2g−1, corresponding to discharge capacity of zinc-air batteries is 169.5, 160.3, 175.2, 171.5, and 112.2mAh, respectively.

The relation between structural features and electrochemical activity of MnO2 nanoparticles synthesized from a polyol-made Mn3O4 precursor

A simple hybrid synthesis processing method was developed to synthesize γ-MnO2 nanocrystalline particles. The polyol method was modified by the addition of nitric acid in order to allow the synthesizing of single-phase Mn3O4 in a large scale. In the sequence, the acid digestion technique was used to transform Mn3O4 into γ-MnO2. Structural and morphological characterization was carried out by X-ray diffractometry, Infrared and Raman spectroscopy, thermogravimetric analysis, nitrogen adsorption isotherm, scanning electron microscopy, and transmission electron microscopy. The electrochemical properties were investigated by cyclic voltammetry and galvanostatic charge–discharge measurements. The synthesized material exhibits a specific capacitance of 125.1 F g−1 at a mass loading of 0.98 mg cm−2. The relation between structural features and electrochemical activity is discussed by comparing the synthesized material with commercial electrolytic manganese dioxide.

Facile synthesis of α-MnO 2 nanorods for high-performance alkaline batteries

Single-crystalline α-MnO 2 nanorods have been successfully synthesized by a novel hydrothermal method based on the redox reactions between the permanganate anion MnO 4 – and H 2O in mixture containing KMnO 4 and HNO 3. The products have been characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectrum (FT-IR) and Brunauer–Emmett–Teller (BET). The results prove that the grain size of α-MnO 2 nanorods with the surface area ∼95.2 m 2 g −1 is homogeneous with diameters ranging from 10 to 20 nm. The electrochemical property of the material shows that compared with the commercial electrolytic manganese dioxide (EMD), the discharge capacity of the as-prepared α-MnO 2 nanorods is increased by 70.4%, 104.1% and 135.7% at different constant currents of 50, 250 and 500 mA g −1, respectively.

Synthesis and electrochemical properties of two types of highly ordered mesoporous MnO 2

Mesoporous MnO 2 with uniform nanorod morphology and mesoporous β-MnO 2 were prepared using SBA-15 and KIT-6 as the templates, respectively. XRD, nitrogen adsorption analysis, SEM, TEM and EDX techniques were used for the structural characterization. The electrochemical properties of the MnO 2 samples were studied using alkaline Zn/MnO 2 batteries in a 9 M KOH electrolyte solution. Compared to the commercial electrolytic manganese dioxide (EMD), the discharge capacity of the mesoporous MnO 2 nanorods increased by 74.98%, 119.74% and 146.19% at constant currents of 50, 250 and 500 mA g −1, respectively, while the discharge capacity of the mesoporous β-MnO 2 increased by 63.58%, 95.14% and 100.23%.

Carbon-supported manganese oxide nanocatalysts for rechargeable lithium–air batteries

Manganese oxide based catalysts were synthesised in the form of nano-particles using a redox reaction of MnSO 4 and KMnO 4, housed into the pores of a carbon matrix and followed by a thermal treatment. Particle sizes of the manganese oxide nanocatalysts were around 50 nm, based on the tunnelling electron microscope measurement. They were uniformly distributed in the carbon matrix, which contributed to an improved electrical connection among the catalyst and current collectors. The charge/discharge tests using this material as the cathode material in a rechargeable lithium–air battery showed high discharge capacities up to 4750 mAh (g carbon) −1. The cycle ability of the composite electrode was superior to those of the commercial electrolytic manganese dioxide electrodes.

Discharge rate capabilities of alkaline AgCuO 2 electrode

A series of AgCuO 2 samples are prepared and tested as alkaline cathode materials for primary batteries. AgCuO 2 discharges via four equivalent-charge reduction processes, the rate capabilities of which are determined. At ambient temperature AgCuO 2 displays superior rate capabilities for the two highest voltage processes. For all samples, the rate capability of the two lower voltage processes is always superior to those at higher voltage. This is due to the electrode intrinsically doping itself with elemental silver during discharge as part of the second reduction process. The electrode compares favourably with commercial electrolytic manganese dioxide but is prone to self-discharge, the kinetics of which are also discussed.

Preparation and characterisation of chemical manganese dioxide: Effect of the operating conditions

In this study MnO 2 preparation by chemical methods is investigated for possible applications in dry cell batteries of chemical manganese dioxide (CMD) instead of electrolytic manganese dioxide (EMD). Three preparation procedures were tested: precipitation–oxidation by air plus acid activation (two-step-air), precipitation–oxidation by H 2O 2 plus acid activation (two-step-H 2O 2), precipitation–oxidation by KClO 3 (single-step-ClO 3). Replicated factorial designs and related statistical analysis of experimental data by analysis of variance were performed in order both to obtain a preliminary optimization of the operating conditions and to take into account the intrinsic sample heterogeneity associated to each specific procedure. Comparisons among three different preparations denoted that in the investigated conditions two-step preparations give larger yields of activated solid in comparison with single-step preparation. Preliminary optimized conditions denoted final solid yields (80–86%) for both two-step procedures. The effect of operating conditions on the chemical, structural and electrochemical properties of CMDs produced in preliminary optimised conditions was investigated and compared with those of a commercial EMD sample by acid and acid-reducing leaching for Mn speciation in solid phase, potentiometric titrations, X-ray and IR spectra and cyclic voltammetry. These characterisation tests denoted the significant effect of acid activation in both preparation procedures to obtain CMD samples with high % of Mn(IV)oxides. Potentiometric titrations of solid samples obtained by first and second steps denoted that both procedures gives two CMD samples with the same acid–base properties, which in comparison with commercial EMD present a residual dissociation in the basic pH range (similar structure and proton insertion properties for CMDs and EMD, but different structural defects). X-ray and IR spectra of solid samples by first and second steps denoted highly disordered systems and the presence of Mn 2O 3 in first step products and of γ-MnO 2 in second step product. Voltammetric cycles denoted that CMD samples obtained after acid digestion present similar peaks than commercial EMD but with higher current intensity.

Kinetics of Heavy Metal Ion Adsorption on to, and Proton Release from, Electrolytic Manganese Dioxide

The kinetics of adsorption of lead(II), as well as of copper (II), zinc(II) and thallium(I), on commercial electrolytic manganese dioxide (EMD) powder of different size fractions has been followed by a pH-stat method involving the computer-controlled neutralisation of released protons from the EMD at a fixed pH with hydroxide ion. Base uptake versus time profiles in all cases indicated a rapid initial change followed by a slower process. These can be interpreted in terms of either a solution kinetic model or an adsorption kinetic model. In the former analysis, the adsorption-time profile can be interpreted in terms of two, or at most three, exponentials. The contribution of the first fast step increases with decreasing average particle size (or increasing surface area), consistent with its interpretation as being associated with the replacement of accessible protons on the exposed surface of the EMD by metal ions. The slower rate processes can be considered to be associated with adsorption in less accessible clefts or pores in the structure. In the diffusion model, the experimental data were fitted to the equation of diffusion in a sphere, fitting again requiring a first initial step followed by a slower step, with one diffusion coefficient having typically an upper limit of 10-9 and the other a lower limit of 10-11 cm2/s. For the complete reaction, the moles of protons released per mole of metal ion adsorbed were also measured and found to be relatively insensitive with respect to pH, metal ion concentration, electrolyte concentration and EMD size fraction. At pH 4, the H+: Mn+ ratio ranged from 1.4 to 2.1 (±0.1) for divalent transition metal ions, consistent with dominant chelation of the divalent metal ion to two adjacent oxygen sites on the surface; for thallium(I), a low ratio (0.5) indicated a different mode of surface attachment.

オゾン酸化によって酸性硫酸マンガン溶液から析出した二酸化マンガン粒子

Manganese dioxide was precipitated from slightly and strongly acidic solution of manganese sulfate by ozone oxidation at temperatures up to 80°C. The particles were characterized by SEM observation and X-ray diffraction.Ozone was found to be very effective to produce manganese dioxide even at acid concentration as high as 5.0mol/l.The size and surface morphology of the particle were strongly affected by acidity and temperature. At pH 2 or 3, the particles were as small as about 0.2μm and had rugged surface. Particles consisted of nearly spherical grains of a size of 1-2μm with smooth surface at 1 or 2mol/l H2SO4. The particle surface turned rougher and finally was covered almost uniformly with thin needle-like crystals as the acid concentration increased up to 5.0mol/l. It was observed that the particle had rougher surface as the reaction temperature was raised.X-ray diffraction analysis showed that γ-MnO2 was a main reaction product under the conditions excluding pH 3.0 and 5.0mol/l H2SO4 at 80°C where α-MnO2 was detected.Also, use of ozone was proved to enable us to produce very fine particles of manganese dioxide with discharge behavior comparable to commercial electrolytic manganese dioxide for a battery-active material.