Manganese-based Oxides Research Articles

Na+ diffusion mechanism and transition metal substitution in tunnel-type manganese-based oxides for Na-ion rechargeable batteries

Structural, computational and electrochemical investigations are combined to study the intercalation properties of tunnel-type Na0.44MnO2 and Cu-substituted Na0.44MnO2.

Na+/vacancy disordered manganese-based oxide cathode with ultralow strain enabled by tuning charge distribution

Introducing electropositive Sn4+ into TMO2 layer increases the charge density around O, reduces the Na–TM and Na–Na electrostatic repulsions as well as the electron delocalization, thus disturbing the charge ordering and facilitating Na+ diffusion.

A superior catalyst for ozone decomposition: NiFe layered double hydroxide

Ground-level ozone is harmful to human beings and ecosystems, while room-temperature catalytic decomposition is the most effective technology for ozone abatement. However, solving the deactivation of existing metal oxide catalysts was caused by oxygen-containing intermediates is challenging. Here, we successfully prepared a two-dimensional NiFe layered double hydroxide (NiFe-LDH) catalyst via a facile co-precipitation method, which exhibited stable and highly efficient performance of ozone decomposition under harsh operating conditions (high space velocity and humidity). The NiFe-LDH catalyst with Ni/Fe = 3 and crystallization time over 5 hr (named Ni3Fe-5) exhibited the best catalytic performance, which was well beyond that of most existing manganese-based oxide catalysts. Specifically, under relative humidity of 65% and space velocity of 840 L/(g·hr), Ni3Fe-5 showed ozone conversion of 89% and 76% for 40 ppmV of O3 within 6 and 168 hr at room-temperature, respectively. We demonstrated that the layered structure of NiFe-LDH played a decisive role in its outstanding catalytic performance in terms of both activity and water resistance. The LDH catalysts fundamentally avoids the deactivation caused by the occupancy of oxygen vacancies by oxygen-containing species (H2O, O−, and O2−) in manganese-based oxide. This study indicated the promising application potential of LDHs than manganese-based oxide catalysts in removal of gaseous ozone.

Clarifying the Roles of Cobalt and Nickel in the Structural Evolution of Layered Cathodes for Sodium-Ion Batteries.

Layered sodium manganese-based oxides are appealing cathode candidates due to their high capacity and cost-effectiveness, yet performance degradation related with unwanted structural evolution still remains a disturbing disadvantage. Herein, atomic resolution STEM (scanning transmission electron microscopy) images of Na-extracted Na2/3NixCo1/3-xMn2/3O2 (x = 0, 1/6, 1/3) are collected and analyzed, to decipher the effect of cobalt and nickel substitution on the structural integrity of layered manganese-based oxides. Cobalt substitution is demonstrated to alleviate the lattice stress and retain the layered structure after sodium removal, and only a local P2-to-O2 phase transition could be identified. By contrast, various types of defects and phase transformation, including rarely reported P2-to-O3, are discovered in the Ni-substituted oxides. The generation of spinel and rock-salt phases is the critical evidence of cation mixing that leads to unrecoverable capacity loss. The interplay of different transition metals is complex, and compositional optimization is encouraged to minimize the effect of the concomitant phase transition.

Enhancing Electrochemical Performance of Layered Birnessite Materials with Metal Ions Intercalated Cation for Aqueous Zinc-Ion Batteries

Recently, rechargeable aqueous-based batteries become promising candidates owing to their cost-effectiveness, environmental friendliness, and high safety. Furthermore, aqueous electrolytes provide high ionic conductivity and also provide facile manufacturing processes. Among all rechargeable aqueous-based batteries, aqueous Zn-based batteries (AZBs) exhibit low redox potential (-0.76 V vs standard hydrogen electrode (SHE)) and high theoretical capacity of the Zn metal anode (840 mAh g-1), leading to superior energy density as compared to other low-cost batteries. However, there are many challenges remaining for AZBs including the cathode dissolution limiting their practical applications. Manganese-based oxides are promising cathode materials for AZBs due to their low cost and low toxicity. Moreover, there are various valence states of manganese (Mn2+, Mn3+, Mn4+, and Mn7+) and different crystallographic structures, including ɑ-, β-, γ-, δ-, and λ-MnO2. According to promising manganese-based oxides, δ-MnO2 is one of the most interesting materials because it exhibits a high theoretical capacity of about 616 mAh g-1. Also, the δ-MnO2 or layered structure provides a facile Zn2+ insertion, leading to high-rate capability. However, this structure is facing collapse issue during cycling, resulting in poor stability. In this work, we demonstrate the facile synthesis method of δ-MnO2 and investigate the effect of intercalated cations on its electrochemical performance towards AZBs. The as-fabricated Zn-MnO2 battery achieves 200 mAh g-1 at 0.1 A g-1 and high stability up to 68% after 200 cycles at 1 A g-1.

Manganese-based oxide layer with oxygen vacancies to enable fast ion/charge mobility for durable LiNi0.8Co0.1Mn0.1O2 cathode

Manganese-based oxide layer with oxygen vacancies to enable fast ion/charge mobility for durable LiNi0.8Co0.1Mn0.1O2 cathode

Ultralow-strain Ti substituted Mn-vacancy layered oxides with enhanced stability for sodium-ion batteries

Anionic redox reaction (ARR) in layered manganese-based oxide cathodes has been considered as an effective strategy to improve the energy density of sodium-ion batteries. Mn-vacancy layered oxides deliver a high ARR-related capacity with small voltage hysteresis, however, they are limited by rapid capacity degradation and poor rate capability, which arise from inferior structure changes due to repeated redox of lattice oxygen. Herein, redox-inactive Ti4+ is introduced to substitute partial Mn4+ to form Na2Ti0.5Mn2.5O7 (Na4/7[□1/7Ti1/7Mn5/7]O2, □ for Mn vacancies), which can effectively restrain unfavorable interlayer gliding of Na2Mn3O7 at high charge voltages, as reflected by an ultralow-strain volume variation of 0.11%. There is no irreversible O2 evolution observed in Na2Ti0.5Mn2.5O7 upon charging, which stabilizes the lattice oxygen and ensures the overall structural stability. It exhibits increased capacity retention of 79.1% after 60 cycles in Na2Ti0.5Mn2.5O7 (17.1% in Na2Mn3O7) and good rate capability (92.1 mAh g−1 at 0.5 A g−1). This investigation provides new insights into designing high-performance cathode materials with reversible ARR and structural stability for SIBs.

Urea-assisted mixed gas treatment on Li-Rich layered oxide with enhanced electrochemical performance

Lithium-rich manganese-based oxides (LRMOs) have been considered as one of the most promising cathode materials owing to their superior specific capacity and high operating voltage. However, their large-scale commercial applications are limited due to problems such as structural instability, voltage decay, and poor cycle stability. Herein, pre-generated oxygen vacancies and oxygen-deficient phase were introduced to Li1.2Mn0.6Ni0.2O2 (LMNO) using a facile urea-assisted mixed gas treatment (UMGT) method for facilitating electronic and ionic conductivity, reducing the surface oxygen partial pressure, and suppressing the release of lattice oxygen. Compared with the pristine LMNO material, the UMGT sample modified at 200 °C exhibited enhanced discharge capacity, capacity retention, and rate capability. In addition, the Li+ diffusion coefficient significantly improved by 50% than that of the reference LMNO. More importantly, the voltage decay was effectively suppressed, with average potential decreasing from 0.53 V (LMNO) to 0.39 V (UMGT-200) after 200 cycles at 1 C. The proposed UMGT method provides an effective strategy to alleviate the phase transition and improve the electrochemical performance for lithium-rich materials, and identifies a promising research direction to inhibit the voltage decay of layered anion redox cathode materials.

Tuning oxygen redox chemistry of P2-type manganese-based oxide cathode via dual Cu and Co substitution for sodium-ion batteries

High-voltage layered Mn-based oxide is promising high-capacity cathode via exploiting the oxygen redox chemistry. But such redox often suffer from irreversible oxygen loss, leading to severe voltage hysteresis, particle cracking and capacity decay. Hence, the complementary strategy of dual Cu and Co substitution is revealed to stabilizing the anion redox chemistry of P2-Na2/3(Mn-Ni-Cu-Co)O2 cathode under upper cut-off voltage. Dual substitution with Cu for Mn and Co for Ni forms stable Cu-O and Co-O octahedrons, which modulate the lattice structure with the shrinkage of TMO2 sheets and expansion of Na layer spacing to enhance the Na+ diffusion kinetics. Co substitution can raise high voltage region to tune the cut-off voltage up to 4.3 V and activate oxygen redox to weaken irreversible O2 loss. And Cu substitution can inhibit the O2 loss and suppress the voltage decay via the interaction between Cu 3d and O 2p orbitals. The P2-type Na0.67Mn0.6Ni0.2Cu0.1Co0.1O2 cathode induced by the complementary effect can boost long cycling life (82.07% capacity retention after 500 cycles) and remarkable rate capability under high upper cut-off voltage in half-cell. Furthermore, the full cells also exhibit outstanding rate capability with a high discharge capacity of 62.6 mAh g–1 at 20 C.

Surface modification of manganese monoxide through chemical vapor deposition to attain high energy storage performance for aqueous zinc–ion batteries

Surface modification of the manganese-based oxide electrode is considered to be a viable strategy to improve electrochemical property in aqueous zinc-ion batteries (ZIBs). However, the modification method through traditional wet-chemical technology can hardly to satisfy high rate capability for aqueous ZIBs due to unhomogeneous and nonconformal coating originates from surface energy mismatch. Herein, a surface modification strategy based on chemical vapor deposition is developed to enhance the electrochemical property of the inactive MnO in aqueous ZIBs. The constructed carbon coating modified MnO electrode shows excellent reversible capacity and superior rate capability with remarkable energy density of 351 Wh kg−1 at 625 W kg−1. The energy storage mechanism of the electrode during the charge and discharge processes is elucidated according to the ex-situ measurements of X-ray diffraction and photoelectron spectroscopy, Fourier transform infrared spectra, and galvanostatic intermittent titration techniques. Moreover, soft-packaged batteries are fabricated with the carbon coating modified MnO, which shows great promises for the practical application of the material. The work paves the way for the exploitation of high performance surface-modified electrode through chemical vapor deposition for aqueous ZIBs.

MnCo2S4 – MXene: A novel hybrid electrode material for high performance long-life asymmetric supercapattery

The supercapattery, an ideal electrochemical energy storage device, which can deliver high energy like battery and high power like supercapacitor. Transition metal sulphides’ energy storage capabilities have unfurled beyond the realm of ruthenium and manganese-based oxides by the versatile affordable sulphospinel transition metal sulphides such as MnCo2S4 (MCS). The advancement of synergistic nano-architectures of these transition metal sulphides with two-dimensional MXene material adulated the conductivity and highly reversible redox nature. The hybrid MCS-MXene was synthesised through facile cost effective hydrothermal method and the material were characterised using basic X-Ray Diffraction (XRD) to advanced tools as like electron energy loss spectroscopy (EELS). The electrochemical results depict that the supercapattery electrode of 2D synergistic MCS-MXene hybrid architectures shows highly improved specific capacitance of 600 C/g at 1 A/g current density than pristine MXene and MCS. The fabricated asymmetric supercapattery using hybrid MCS-MXene and bio-derived activated carbon (AC) shows a high specific energy and power density of 25.6 Wh/kg and 6400 W/kg, respectively with excellent cycling stability of 100% capacitance retention after 12,000 cycles.

Insight of K-deficient layered KxMnO2 cathode for potassium-ions batteries

Potassium-ions batteries (PIBs) are attracting increasing attention as up-and-coming youngster in large-scale grid-level energy storage benefiting from its low-cost and high energy density. Nevertheless, enough researches regarding indispensable cathode materials for PIBs are badly absent. Herein, we synthesize K-deficient layered manganese-based oxides (P2-K0.21MnO2 and P3-K0.23MnO2) and investigate them as cathode of PIBs for the first time. As the newcomer of potassium-containing layered manganese-based oxides (KxMnO2) group, P2-K0.21MnO2 delivers high discharge capacity of 99.3 mAh g−1 and P3-K0.23MnO2 exhibits remarkable capacity retention rate of 75.5%. Besides, in-situ XRD and ex-situ XRD measurements reveal the reversible phase transition of P2-K0.21MnO2 and P3-K0.23MnO2 with the potassium-ions extraction and reinsertion, respectively. This work contributes to a better understanding for the potassium storage in K-deficient layered KxMnO2 (x ≤ 0.23), possessing an important basic scientific significance for the exploitation and application of layered KxMnO2 in PIBs.

Manganese oxides hierarchical microspheres as cathode material for high-performance aqueous zinc-ion batteries

For manganese-based oxides to be used as one of the most promising aqueous zinc-ion batteries (ZIBs) cathode materials, improvements in cycling stability are required. In this work, manganese oxides (MnOx) hierarchical microspheres, including MnO, γ-MnO2 (MnO2), Mn2O3 and Mn3O4, are prepared and their electrochemical performances are systematically investigated as cathode materials for aqueous ZIBs. The MnOx hierarchical structures can effectively shorten the diffusion pathway of Zn2+, tolerate the structural stress caused by Zn2+ insertion/extraction and restrain the self-aggregation of nanomaterials. Among MnOx, MnO hierarchical microspheres displays a high reversible capacity of 376.7 mAh g−1, good rate capability and excellent cycling stability with capacity retention of 99.37% over 1000 cycles. Finally, the zinc ion storage mechanism of MnO cathode is revealed. The results show that the remarkable electrochemical performance of MnO cathode is attributed to layered-type MnO2 structure formed during the initial few cycles, which is conducive to the insertion/extraction of zinc ions. This work is expected to deepen the understanding of the energy storage mechanism of MnO and helped to choose the ideal manganese-based cathode materials for aqueous ZIBs.

Recent Progress of Thermocatalytic and Photo/Thermocatalytic Oxidation for VOCs Purification over Manganese-based Oxide Catalysts.

Volatile organic compounds (VOCs) are one of the main sources of air pollution, which are of wide concern because of their toxicity and serious threat to the environment and human health. Catalytic oxidation has been proven to be a promising and effective technology for VOCs abatement in the presence of heat or light. As environmentally friendly and low-cost materials, manganese-based oxides are the most competitive and promising candidates for the catalytic degradation of VOCs in thermocatalysis or photo/thermocatalysis. This article summarizes the research and development on various manganese-based oxide catalysts, with emphasis on their thermocatalytic and photo/thermocatalytic purification of VOCs in recent years in detail. Single manganese oxides, manganese-based oxide composites, as well as improving strategies such as morphology regulation, heterojunction engineering, and surface decoration by metal doping or universal acid treatment are reviewed. Besides, manganese-based monoliths for practical VOCs abatementare also discussed. Meanwhile, relevant catalytic mechanisms are also summarized. Finally, the existing problems and prospect of manganese-based oxide catalysts for catalyzing combustion of VOCs are proposed.

Recent Development of Mn-based Oxides as Zinc-Ion Battery Cathode.

Manganese-based oxide is arguably one of the most well-studied cathode materials for zinc-ion battery (ZIB) due to its wide oxidation states, cost-effectiveness, and matured synthesis process. As a result, there are numerous reports that show significant strides in the progress of Mn-based oxides as ZIB cathode. However, ironically, due to the sheer number of Mn-based oxides that have been published in recent years, there remain certain contemplations with regards to the electrochemical performance of each type of Mn-based oxides and their performance comparison among various Mn polymorphs and oxidation states. Thus, to provide a clearer indication of the development of Mn-based oxides, the recent progress in Mn-based oxides as ZIB cathode was summarized systematically in this Review. More specifically, (1) the classification of Mn-based oxides based on the oxidation states (i. e., MnO2 , Mn3 O4 , Mn2 O3 , and MnO), (2) their respective polymorphs (i. e., α-MnO2 and δ-MnO2 ) as ZIB cathode, (3) the modification strategies commonly employed to enhance the performance, and (4) the effects of these modification strategies on the performance enhancement were reviewed. Lastly, perspectives and outlook of Mn-based oxides as ZIB cathode were discussed at the end of this Review.

Utilization of Promising Calcium Manganite Oxygen Carriers for Potential Thermochemical Energy Storage Application

In this study, oxygen release/consumption behavior of calcium manganese-based oxides (CaMn1–xBxO3, where B: Cu, Fe, Mg and x = 0.1 or 0.2) used in a chemical looping oxygen uncoupling (CLOU) application was investigated. The effect of B-site dopants such as Fe, Mg, and Cu on the oxygen release behavior was also investigated with the aim to use these materials in thermal energy storage (TES). Previous literature studies about CLOU performance of doped calcium manganites were taken into consideration for dopants selection. Calcium manganite-based oxides have been used in chemical looping oxygen uncoupling (CLOU) applications owing to their oxygen release behavior to the gas phase. Studies have revealed that calcium manganite-based oxides show a promising nonstoichiometry over a range of temperatures and oxygen partial pressures, which makes them useful for thermochemical energy storage applications. However, the related literature studies have been mainly focused on their nonstoichiometric characteristics related to temperature and oxygen partial pressure and thermodynamic properties. In this work, thermal analysis and fluidized bed tests were carried out as complementary techniques. CaMn0.8Cu0.2O3 showed the highest oxygen release performance in fluidized bed tests, while CaMn0.9Mg0.1O3 had the best cyclic stability overall among the samples used in the study.

Mitigation of Jahn-Teller distortion and Na+/vacancy ordering in a distorted manganese oxide cathode material by Li substitution.

Layered manganese-based oxides are promising candidates as cathode materials for sodium-ion batteries (SIBs) due to their low cost and high specific capacity. However, the Jahn–Teller distortion from high-spin Mn3+ induces detrimental lattice strain and severe structural degradation during sodiation and desodiation. Herein, lithium is introduced to partially substitute manganese ions to form distorted P′2-Na0.67Li0.05Mn0.95O2, which leads to restrained anisotropic change of Mn–O bond lengths and reinforced bond strength in the [MnO6] octahedra by mitigation of Jahn–Teller distortion and contraction of MnO2 layers. This ensures the structural stability during charge and discharge of P′2-Na0.67Li0.05Mn0.95O2 and Na+/vacancy disordering for facile Na+ diffusion in the Na layers with a low activation energy barrier of ∼0.53 eV. It exhibits a high specific capacity of 192.2 mA h g−1, good cycling stability (90.3% capacity retention after 100 cycles) and superior rate capability (118.5 mA h g−1 at 1.0 A g−1), as well as smooth charge/discharge profiles. This strategy is effective to tune the crystal structure of layered oxide cathodes for SIBs with high performance.

Improving the capacity of zinc-ion batteries through composite defect engineering.

Aqueous zinc-ion batteries (ZIB) are favored because of their low cost and high safety. However, as the most widely used cathodes, the rate performance and long-term cycle performance of manganese-based oxides are very worrying, which greatly affects their commercialization. Here, MnO2 with composite defects of cation doping and oxygen vacancies was synthesized for the first time. Cation doping promoted the diffusion and transport of H+ and oxygen vacancies weakened the zinc–oxygen bond, allowing more electrons to be added to the charge and discharge process. The combination of these makes α-MnO2 obtain a specific capacity of up to 346 mA h g−1. This inspired us to use different combinations of defect engineering strategies on the materials which can be implemented as a potential method to improve performance for the modification of ZIB cathode materials, such as cation vacancies and anion doping.

Stability Design Principles of Mn-Based Oxides for Acidic Electrolytes

Manganese-based oxides are promising, earth-abundant candidate materials in many electrochemical energy applications in aqueous environments, including supercapacitors,1 electrocatalysis2 and solar fuels.3 The use of these oxides in acidic systems, such as proton-exchange membrane fuel cells and electrolyzers,4,5 is, however, severely limited by the bulk instability of Mn oxide phases according to their Pourbaix diagrams.2 Designing active and stable Mn-based oxide catalysts in acidic electrolytes therefore requires fundamental understanding towards their aqueous stability and dissolution mechanism in acid.In this study, we systematically examined the aqueous stability of Mn-based oxides with a diverse range of chemistry, structures and oxidation states in acidic electrolytes. Decreasing the metal-oxygen covalency, e.g. by having Mn ions with lower nominal oxidation states, was found to weaken the manganese-oxygen bonds, reduce the energy penalty for the formation of Mn vacancies and subsequent ion solvation, rendering poorer stability in acidic solutions. Moreover, we identified the critical role of oxide acid-base chemistry6 in dictating the stability of Mn-based oxides, where lifting up the Fermi levels on the absolute energy scale by decreasing covalency can lead to greater thermodynamic driving force for the surface protonation of these metal oxides, which further weakens the surface metal-oxygen bonds and contributes to the instability of Mn-based oxides in acidic electrolytes. This work highlights the importance of understanding the physical origin of the aqueous stability trends for metal oxides with electronic and/or energetic descriptors, and provides guiding principles for designing oxide catalysts with enhanced stability in acidic systems.

Rechargeable Aqueous Lithium-Ion Batteries with Molybdenum-Based Oxides As Negative Electrode Materials

Organic electrolytes used for commercial lithium-ion batteries, like EC or DMC, are flammable, often resulting in causes of fire accidents. In 1994, an aqueous lithium-ion battery using nonflammable water as electrolyte was reported for the first time, and attention has been paid for the improved safety.1 However, the conventional aqueous electrolyte solution has a narrow electrochemical window, and improvement in energy density was, therefore, needed. In recent years, highly concentrated LiTFSA (TFSA; bis(trifluoromethyl-sulfonyl)amide) aqueous solution has been proposed as aqueous electrolyte solutions with a wider electrochemical window.2,3 In this study, we report electrochemical properties of Mo-based oxides as negative electrode materials for aqueous batteries with the concentrated aqueous electrolyte, and 21 mol kg-1 LiTFSA aqueous solution was used as electrolyte. The Mo-based oxide, Li y Nb2/7Mo3/7O2, 4 is used as a negative electrode for aqueous lithium-ion batteries with spinel-type manganese-based oxide, Li1.05Mn1.95O4, as a positive electrode. Charge/discharge curves of full cells, consisting of Li1.05Mn1.95O4 and Li y Nb2/7Mo3/7O2, are shown in Figure 1. For comparison 1 M LiPF6/EC:DMC = 3/7 by volume and 21 mol g-1 LiTFSA/H2O are used as electrolyte solutions. Both cells show good cyclability at a rate of 1000 mA g-1 and are operable as 2 V-class full cells as shown in Figure 1. Capacity retention of both cells for 1000 cycle test is also shown in Figure 2, and the full cell with the concentrated aqueous electrolyte shows comparable reversibility with aprotic electrolyte solution with similar Coulombic efficiently. From these results, we will further discuss the possibility of Mo-based oxide as potential negative electrode materials for aqueous lithium-ion batteries.References(1)Wu Li, J. R. Dahn, D. S. Wainwright, Science, 264, 1115 (1994).(2)Suo, L. et al., Science 350, 938 (2015).(3)Yamada. et al., Nat. Energy, 1, 16129 (2016).(4)Hoshino et al., and N. Yabuuchi, ACS Energy Lett., 2, 733 (2017). Figure 1