Electrolytic Manganese Dioxide Research Articles

Enhanced electrochemical energy storage devices utilizing a one-dimensional (1D) α-MnO2 nanocomposite encased in onion-like carbon

AbstractThis work describes the fabrication of a novel one-dimensional (1D) α-MnO2 nanorods encased in onion-like carbon (or) carbon nano-onions (OLC) via microwave irradiation techniques employing electrolytic manganese dioxide (EMD), which is especially beneficial for rapid ion and electron transfer, and great structural stability. The composite of α-MnO2 and OLC demonstrates exceptional performance as an electrode across various electrochemical energy storage systems, including zinc-ion batteries (ZIB), sodium-ion batteries (SIB), and supercapacitors (SC) than the pristine α-MnO2. In SIB systems, the composite exhibits a specific capacity of 266 mAh g−1 at initial cycle with 50% capacity retention over 500 cycles, whereas the pristine electrode delivers only 39% capacity retention. The rapid yet controlled charge transfer kinetics facilitated by OLC addition in the α-MnO2 matrix outperforms as the ZIB cathode with an excellent specific capacity of 476 mAh g−1 with 100% capacity retention, while the pristine sample exhibits 77.5% capacity retention. As a SC electrode, the α-MnO2/OLC composite exhibits better electrochemical properties such as rectangular behavior, increased specific capacitance (792 F g−1), excellent capacity retention at high current densities, and others. The higher surface area that could be offered by the OLC to the α-MnO2 matrix facilitates the improved electrochemistry in the pristine sample and this kind of modification can be a viable solution to overcome the limitations of α-MnO2 for electrochemical energy storage applications. It is important to note that the performance outputs of α-MnO2/OLC composite are far better than the regular carbon (graphite, graphene) in α-MnO2 electrodes. Further, OLC provided with high surface area and ordered morphology can play the role of conductivity booster, structural stabilizer, and electrochemical active material in all the energy storage applications which may give a significant research attention in near future.

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.

Regeneration of waste Zn-MnO2 batteries: Value-added transformation to regenerate essential materials for sustainable battery manufacturing

Zn-MnO2 batteries have a 3–5 year shelf life and make up 75 % of portable batteries. Disposing of spent batteries is a global issue and demand for MnO2 cathode material is growing 9.6 % annually, causing increased resource use and potential toxic metal leaching risk. Eco-efficient practices are needed to reduce environmental impact through recycling and reusing end-of-life products. Herein, electrolytic manganese dioxide (EMD) of spent Zn-MnO2 batteries was recycled using a thermochemical process where the structure of EMD was upgraded resulting in improving its electrochemical performance. The applicability of the recycled EMD as cathode into a new battery was explored by examining the discharge behaviour of the Zn-MnO2 cell made in KOH electrolyte and the results were compared with the performance of an original battery/EMD. In the recycled EMD cell, γ-MnO2 transformed to Zn2Mn7O8.H2O upon discharge (with a capacity of 213 mAh.g−1) and no Mn3O4 was observed, whereas in the original EMD, discharge resulted in the formation of mainly ZnMn5O4 and Mn3O4 (with a capacity of 175 mAh.g−1). The reversibility of the intercalation of cations into the structure of γ-MnO2 and their rechargeability was further examined via charge-discharge cycles using LiOH electrolyte where the recycled EMD exhibited enhanced behaviour. This indicates that in the recycled EMD, ZnMnO2 was able to revert to the original γ-MnO2, whereas in the original EMD, the formed Mn3O4 seemed to be irreversible resulting in the poor rechargeability behaviour of such batteries. Conclusively, the proposed method is a more efficient solution for reducing environmental impacts in value-added manufacturing due to its fewer steps compared to conventional techniques.

Spinel LiMn2O4 as Electrocatalyst toward Solid-State Zinc–Air Batteries

Efficient oxygen reduction reaction (ORR) electrocatalysts are the key to advancement of solid-state alkaline zinc–air batteries (ZAB). We demonstrate an electrocatalyst, spinel lithium-manganese oxide LiMn2O4 (LMO) by a simple hydrothermal method. Scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectra indicate that the as-synthesized LiMn2O4 presents nanoscale irregular-shaped particles with the well-known spinel structure. The polarization curve, chronoamperometery curve, and linear scanning voltammograms of rotating disk electrode (RDE) results reveal that the as-synthesized LiMn2O4 possesses a higher electrocatalytic activity than that of electrolytic manganese dioxide for the ORR. A solid-state zinc–air cell with LiMn2O4 as the air electrode catalyst has a long voltage plateau of discharge and a discharge capacity of 188.4 mAh at a constant discharge current density of 10 mA·cm−2. In summary, spinel LiMn2O4 in which the JT effect enables electron hoping between Mn3+ and Mn4+ can be regarded as an effective robust oxygen reduction catalyst.

Impact of high volume E.M.D. residue on the corrosion resistance and mechanical properties of construction materials in sulfate environment

This study examines the potential use of Electrolytic Manganese Dioxide (EMD) residue as a replacement of cement (20%wt by cement weight) in construction materials to provide anticorrosion protection on reinforcing steel and improve the strength of cementitious materials under sulfate attack. To assess the corrosion parameters, the constructed building materials were immersed in a 5%wt sulfate salt (Na2SO4), while concrete samples incorporating 20%wt EMD were prepared and subjected to mechanical, porosity and thermal tests. Moreover, SEM images were obtained in order to examine the microstructure of concrete and the extent of damage caused by sulfate ions. The results demonstrate that the inclusion of EMD caused a notable rise in the corrosion of steel bars within cement mortars, as well as a decrease in the mechanical strength of the building materials. Overall, the experimental outcomes of the study suggest that the incorporation of high volume (20%wt) EMD residue leads to the degradation of all measured properties.

The effect of chaos circuits on the polymorphs of electrolytic manganese dioxide

Electrolytic manganese dioxide (EMD) is the critical component of the cathode material in modern alkaline, lithium, and sodium batteries. Aimed at the remediation of EMD crystalline structures, this research explored the effect of external power-supplying models on EMD structure regulation. The chaos electro circuit was found to impact the characteristics of EMD such as the crystalline structure, also the nanostructure morphology, and the hysteresis behavior.

Increasing the efficiency of secondary resources in the mining and metallurgical industry

An improved methodology is presented for assessing the economic feasibility and effectiveness of recycling industrial waste. The methodology is based on the break-even control mechanism, but at the same time provides for the introduction of new evaluation criteria such as the threshold of conditionality and the degree of ore substitution. Based on an improved analysis, it becomes possible to more precisely predict recycling efficiency. A more refined determination of the lower limit of concentration of recoverable metals, at which technogenic waste can be assigned the status of secondary raw materials and processed profitably, leads to a significant expansion of the secondary raw material base suitable for recycling. The potential for recycling manganese-containing dust from the production of ferrosilicomanganese, dehydrated sludge from the hydro separation of slags, and cake from the production of electrolytic manganese dioxide at the Chiatura mining enterprise is used as an example. It is shown that with a threshold of -24% Mn content, the highest recycling efficiency can be achieved by the production of low-phosphorus manganese slag and conversion to ferrosilicomanganese using the above waste to replace 40-60% grade III and IV manganese concentrates in the feed.

Synergetic control of hydrogen evolution and ion-transport kinetics enabling Zn anodes with high-areal-capacity

Intrinsic uneven Zn deposition-dissolution and hydrogen evolution reaction (HER) induce poor reversibility and limited cycle life of Zn anodes, which thus restrict the practical application of rechargeable aqueous Zn batteries. In this work, a synergistic strategy of porous indium (In) coating layer combined with a polyacrylamide (PAM) polymer layer for Zn anodes is proposed to provide large HER overpotential while facilitating fast and homogeneous Zn2+ transport at the electrode-electrolyte interface. The corrosion reaction and Zn dendrite growth are simultaneously prevented at high utilization of Zn anodes. The optimal ZnIn-PAM electrodes demonstrate outstanding cycling stability at ultra-high current density and areal capacity (10 mA cm−2, 10 mAh cm−2, Zn utilization: 57%) for over 400 h, and long-term lifespan for over 1700 h at 5 mA cm−2 and 5 mAh cm−2 (Zn utilization: 28.5%) with only ∼50 mV overpotential. Coupled with electrolytic manganese dioxide cathode, the full cell delivers ultra-long lifespan of 10000 cycles with capacity decay rate of 0.006% per cycle at 5 C. This work provides useful perspective for exploring synergetic strategies to address the limited cycling stability of Zn metal-based aqueous batteries for practical use.

The Effects of the Carbon Materials and the Electrolyte Content on the Second-Electron Reaction of Electrolytic MnO2 in Alkaline Systems

A low-cost battery with high energy density, high safety, and made with low scarcity material is needed for stationary storage applications. Electrolytic manganese dioxide (EMD), which is non-toxic, abundant, and low cost, is suitable for such applications. EMD has a high theoretical energy density (617 mAh g-1) for its two-electron reaction. However, most previous works focused on the first-electron reaction of EMD, which only provides an energy density of 308 mAh g-1. The dissolution-precipitation process during the second electron reaction of MnO2 based cathode was regarded as the main reason for the formation of Mn3O4 and will greatly affect the cycling stability of the electrode.1Recent works found that additives like Bi2O3 and Cu could help form a stable birnessite phase and suppress the dissolution of manganese during cycling, resulting in a very stable cycling performance.2However, the mass loading of the active material in these studies was still low and required additives like carbon nanotubes, which are not commercially favorable.In our work, we investigated the EMD second-electron reaction in an electrolyte-lean T-cell system, with very little excess electrolyte. We compared EMD performance in the T-cell with its performance in the electrolyte-flooded beaker cell system at different cycling rates in both KOH and NaOH electrolytes. We found a huge improvement in the stability of EMD when cycled in the electrolyte-lean T-cells especially with NaOH electrolyte (Fig. 1a). We also explored the influence of different carbon materials, including multi-walled carbon nanotube (MWCNT), graphite and Super P carbon blacks in the electrolyte-lean system (Fig. 1b). Different carbon materials were found to have a great impact on both capacity and cycling stability performance of the EMD cathode, possibly due to differences in the specific surface area and the pore sizes of the carbon materials. Electrodes with higher EMD loading and chemically synthesized Bi-doped birnessite material were also tested in the T-cell system to find a more economically favorable electrode composition. Scanning electron microscopy, X-ray diffractions, and other techniques were used to evaluate the phase change and morphology difference during the cycling process.Figure 1. (a) Comparison between T-cells with 37 wt.% KOH with 21 wt.% NaOH as electrolyte with a normal beaker cell with 37 wt.% KOH electrolytes. The electrodes composed of 60 wt.% EMD, 12 wt.% Bi2O3, 14 wt.% Cu, 10 wt.% MWCNT and 4 wt.% PTFE, NiOOH were used as anodes. The C-rate of all tests is C/3. (b) Comparison between different carbon material materials that used in the electrode in T-cells. The electrodes composed of 60 wt.% EMD, 12 wt.% Bi2O3, 14 wt.% Cu, 10 wt.% carbon material and 4 wt.% PTFE, NiOOH were used as anodes and 30 wt.% NaOH was used as electrolyte. The C-rate of all tests is C/3. G. S. Bell and R. Huber, Electrochim. Acta, 10, 509–512 (1965).G. G. Yadav, J. W. Gallaway, D. E. Turney, M. Nyce, J. Huang, X. Wei, and S. Banerjee, Nat. Commun., 8, 1–9 (2017). Figure 1

Statistical Approach to Design Zn Particle Size, Shape, and Crystallinity for Alkaline Batteries

The modern alkaline primary battery is composed of a highly alkaline, gelled electrolyte-zinc powder anode dispersion (slurry), a cellulose-based separator, and an electrolytic manganese dioxide (EMD) cathode pellet – typically arranged in a cylindrical cell geometry. This battery system has its origins in the 1950s and thus has had decades to be researched and matured and it is known that the limiting performance of this battery system is concentrated at the slurried zinc anode. This had led many researchers to focus on the anode for improvement with most previous engineering efforts targeting enhanced performance, capacity, and stability of this material. Due to the various material fabrication processes involved with manufacturing industrial zinc powder, there exists an array of unique zinc particle size, shape, and crystallinity combinations that distinguish industrial zinc powders from one another. These industrial zinc powders are typically produced through trial-and-error processes using existing “rules of thumb”. Consequentially, it is possible that something has been missed and a data-driven approach could elucidate the optimum combination of zinc particle properties.In this study, we investigate the effect of Zn particle size, shape, and degree of crystallinity on the achievable capacity and corrosion current. Various types of zinc powders were sieved into size fraction ranges and chemically and thermo-chemically treated to control their crystallinity. The procedure for producing zinc powders of various sizes, shapes, and crystallinities led to a 64-powder Zn matrix that was then electrochemically analyzed by linear sweep voltammetry to determine the corrosion current and galvanostatically discharged to determine the achievable capacity. These experiments were done in a newly-designed, custom-built electroanalytical cell that will be described in the talk. Following the data collection, a 4k factorial statistical analysis was performed. This analysis identified which of the controlling variables have a statistically significant influence on the achievable capacity and corrosion. The statistical model was also able to provide guidance regarding the preferred particle shape. This information can be used to develop actionable procedures for battery manufacturers to create cells that are more stable, longer lasting, and have higher energy densities.

An Investigation on the Factors Affecting Self-Discharge in Li/CFx-MnO2 Hybrid Primary Batteries

Lithium/Carbon fluoride (Li/CFx) primary batteries have been used in commercial applications, for example implantable cardiac pacemakers, due to their high energy density, long shelf life, and wide operation temperature range (-40oC to 85oC). However, the low electrical conductivity of CFx leads to a serious initial voltage delay at the beginning of discharge and the low rate capability of Li/CFx primary batteries. To overcome these issues, CFx materials are mixed with manganese dioxide (MnO2) to form hybrid cathodes due to a good rate capability of MnO2. Generally, the electrolytic manganese dioxide (EMD) used as cathode materials in Li/MnO2 primary batteries contains about 5% of water before heat treatment. The pristine EMD materials were heat-treated to reduce the water contents. However, water can be reabsorbed by cathode materials during processing and cathode formation. In this study, we investigated the effects of residual water contents in the pristine heat-treated EMD materials and as-fabricated CFx-MnO2 cathode electrodes on the self-discharge characteristics in Li/CFx-MnO2 primary batteries. Moreover, we investigated the effect of protective film on Li anode surface on the self-discharge characteristics in Li/CFx-MnO2 primary batteries. A protective film on Li anode surface was formed by immersing it in the electrolyte or carbon dioxide treatment. We believe that this study will provide useful guidance in the enhanced electrochemical properties and fabrication process of Li/CFx-MnO2 primary batteries.

Surfactant-mediated electrodeposition of a pseudocapacitive manganese dioxide a twofer

Electrochemical energy storage is one of the most promising ways of storing energy from intermittent, renewable sources. To meet the needs, the development of scalable, earth-abundant, chemically stable, and environmentally friendly electrode materials is crucial. This work presents four cationic surfactant-mediated manganese sulfate electrolytic solutions used for the synthesis of electrolytic manganese dioxide (EMD) to produce scalable material that satisfies the pre-requisites desired for supercapacitor applications. The influence of the surfactant molecular structure, its concentration, and its interaction in the electrolytic sulfate bath was studied, which opens up new possibilities for the fabrication of the supercapacitor electrode. The performance of three surfactants (Tetradecyltrimethylammonium bromide, Didodecyldimethylammonium bromide, Benzyldodecyldimethylammonium bromide) was benchmarked against the widely used Cetyltrimethylammonium bromide under identical conditions. The surfactants were chosen based on their different head groups and hydrocarbon chains. Benzyldodecyldimethylammonium bromide-assisted EMD (EMD/B-AB) in a single-electrode device showed improved capacitance of 602 F g−1 (at 1 mA cm−2) over the other surfactant-mediated samples. The molecular dynamics simulations indicated that the electrodeposition of manganese dioxide is highly influenced by B-AB, as it adsorbs with the aryl group planar to the Pb surface. The appropriate concentration of B-AB surfactant in the bulk solution appears to be incorporated into the EMD deposit due to their hydrophobic nature and controlled nucleation and established improved pseudocapacitive performance to score a twofer. The asymmetric capacitor of EMD/B-AB30 vs. porous activated carbon exhibited a high specific capacitance of 91 F g−1, with an energy density of 32.4 Wh kg−1 for a corresponding power density of 971 W kg−1.

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

Electrochemical Stability of ZnMn2O4: Understanding Zn-Ion Rechargeable Battery Capacity and Degradation

We present a refined Mn-Zn-H$_2$O Pourbaix diagram with the emphasis on parameters relevant for the Zn/MnO$_2$ rechargeable cells. It maps out boundaries of electrochemical stability for MnO$_2$, ZnMn$_2$O$_4$, ZnMn$_3$O$_7$, and MnOOH. The diagram helps to rationalize experimental observation on processes and phases occurring during charge/discharge, including the position of charge/discharge redox peaks and capacity fade observed in rechargeable aqueous Zn-ion batteries for stationary storage. The proposed Pourbaix diagram is validated by observing the pH-dependent transformation of electrolytic manganese dioxide to hetaerolite and chalcophanite during discharge and charge, respectively. Our results can guide the selection of operating conditions (the potential range and pH) for existing aqueous Zn/MnO$_2$ rechargeable cells to maximise their longevity. In addition, the relation between electrochemical stability boundaries and operating conditions can be used as an additional design criterion in exploration of future cathode materials for aqueous rechargeable batteries.

Bench-Scale Electrowinning of Electrolytic Manganese Dioxide Using Ferruginous Mn Ores as Precursor

Bench-Scale Electrowinning of Electrolytic Manganese Dioxide Using Ferruginous Mn Ores as Precursor

Facile electrode additive stabilizes structure of electrolytic MnO2 for mild aqueous rechargeable zinc-ion battery

MnO2 is a potential cathode material for aqueous zinc-ion battery (ZIB) because of its high capacity, low toxicity and low cost. Though, 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, though it cannot prevent the formation of inactive ZnMn2O4 from reaction between MnO2 and zincate ions. Here, we show that Bi2O3 additive in the electrode can suppress ZnMn2O4 formation and improve cyclability of electrolytic manganese dioxide (EMD). EMD electrode with 10 wt% Bi2O3 in ZnSO4 electrolyte without Mn2+ additive maintains a high capacity of 229 mAh g−1 at 100 mA g−1 after 100 cycles, with a capacity retention of 78%, in comparison with the 8% capacity retention for EMD electrode without Bi2O3. Characterizations suggest that bismuth is able to interact with zinc under alkaline condition and reduce the amount of zincate ions in the electrolyte. Combining both Bi2O3 electrode additive and Mn2+ electrolyte additive, EMD can give a base capacity of about 300 mAh g−1 at 0.3C and maintain a stable capacity of 190 mAh g−1 for 1000 cycles at 1000 mA g−1 (about 3.3C).

Influence of Different Waste Materials on Resistance of Cement Mortars against Carbonation and Chloride Ingress

This work is an extensive experimental study on the corrosion behavior of reinforced cementitious mortars containing industrial byproducts and waste materials. In particular, calcareous (C-class) fly ashes, iron mill scale and Electrolytic Manganese Dioxide (E.M.D.) waste were used as additives in mortars production. The abovementioned materials were used without any prior treatment or management and replaced the cement in concrete mixing by 10% wt. of cement weight. For the experimental set-up, reinforced mortars were prepared and exposed to coastal area for 12 months, while some of them were remained in a salt spray cabin for 60 days. The corrosion monitoring was performed by electrochemical and mass loss measurements, while chloride content, porosity, carbonation and mineralogy of mortars were also estimated. The results indicate, that there is a development in durability and chloride penetration resistance of composites comparing with the conventional mortars at late ages. At the same time, it was also observed that their chemical composition and fineness, control the diffusion of CO2 into the pore system and lead to increased carbonation of composite mortars. The challenge of this work is the production of eco-friendly composites with high chloride and carbon dioxide penetration resistance.

Reaction mechanisms for electrolytic manganese dioxide in rechargeable aqueous zinc-ion batteries

This study reports the phase transformation behaviour associated with electrolytic manganese dioxide (EMD) utilized as the positive electrode active material for aqueous zinc-ion batteries. Electrochemical techniques, including galvanostatic charge–discharge and rotating ring-disk electrode measurements, and microstructural techniques, using X-ray powder diffraction, scanning electron microscopy, and transmission/scanning transmission electron microscopy, were utilized to characterize the positive electrode at different stages of discharge and charge of zinc-ion cells. The results indicate that, during discharge, a fraction of EMD undergoes a transformation to ZnMn2O4 (spinel-type) and Zn2+ is intercalated into the tunnels of the γ- and ε-MnO2 phases, forming ZnxMnO2 (tunnel-type). When a critical concentration of Mn3+ in the intercalated ZnxMnO2 species is reached, a disproportionation/dissolution reaction is triggered leading to the formation of soluble Mn2+ and hydroxide (OH–) ions; the latter precipitates as zinc hydroxide sulfate (ZHS, Zn4(OH)6(SO4)·5H2O) by combination with the ZnSO4/H2O electrolyte. During charge, Zn2+ is reversibly deintercalated from the intergrown tunneled phases (γ-/ε-ZnxMnO2), Mn2+ is redeposited as layered chalcophanite (ZnMn3O7·3H2O), and ZHS is decomposed by protons (H+) formed during the electrochemical deposition of chalcophanite.

The Effects of Electrolytes and Cycling Protocols on Bi-Birnessite Cathode for Alkaline Batteries

Stationary batteries need to be low-cost, highly energy-dense, safe, reliable, and made with abundant materials using simple manufacturing methods. MnO2 is abundant, low-cost, non-flammable, non-toxic, & has a high theoretical capacity of 617 mAh g-1. The phase changes of MnO2 during cycling are a significant determinant of the system’s reversibility. Electrolytic manganese dioxide, or γ-MnO2, is the most commonly used polymorph, frequently paired with Zn anodes in commercial primary batteries.1 In secondary batteries, long-lasting reversibility of γ-MnO2 cathodes requires limiting depth-of-discharge (DoD) to 5-10% of capacity to prevent the formation of additional MnO2 polymorphs. Alternatively, layered δ-MnO2, or birnessite, can deliver 60-80% of theoretical capacity but usually requires low active mass loading and has a low cycle-life due to the irreversible formation of Mn3O4. The use of copper and Bi2O3 additives was recently found to mitigate many birnessite problems, resulting in a cathode with high active mass loading that delivered full theoretical capacity for thousands of cycles.2 Furthermore, the birnessite was electrochemically synthesized from γ-MnO2 in situ, making the system even more attractive for commercialization. However, eliminating copper and replacing KOH with NaOH would make the system much more economically favorable. In this work, we investigated the sensitivity of Bi-birnessite’s cycle life to electrolyte type and cycling protocols. We compared the cycle life of Cu-intercalated Bi-birnessite in KOH to that of Bi-birnessite, with and without copper, in NaOH. We also evaluated the influence of depth-of-discharge on the capacity fade behavior of the cathode in NaOH. Finally, we assessed the performance of the cathode under a slow, shallow cycling protocol that simulates seasonal, long-term energy storage behavior. X-ray diffraction (XRD) was used at various points in the cathode’s cycle life to determine the phase evolution of the material. By extrapolating from the XRD and cycling data, we will compare the roles of KOH to NaOH and Cu2+ to Na+ in the system, respectively.References Shin, J., Seo, J. K., Yaylian, R., Huang, A. & Meng, Y. S. A review on mechanistic understanding of MnO2 in aqueous electrolyte for electrical energy storage systems. Int. Mater. Rev. 65, 356–387 (2020).10.1080/09506608.2019.1653520. Yadav, G. G. et al. Regenerable Cu-intercalated MnO2 layered cathode for highly cyclable energy dense batteries. Nat. Commun. 8, 14424 (2017). 10.1038/ncomms14424.

(Industrial Electrochemistry and Electrochemical Engineering Division New ElectrochemicalTechnology (NET) Award) Development and Commercialization of Rechargeable Zinc Manganese Alkaline Batteries to Enable a Sustainable Low-Carbon Energy Future

Urban Electric Power Inc. (UEP), a 2013 spinoff from the City University of New York Energy Institute (CUNY-EI), manufactures and markets rechargeable large-format zinc manganese dioxide (Zn-MnO2) alkaline battery cells in Pearl River, NY. The active materials in the UEP rechargeable cells are Zn and MnO2, both of which have high energy density, low cost, good safety characteristics, and are readily available with abundant supplies. These materials are key components of primary (non-rechargeable) alkaline batteries that presently dominate the disposable battery market, showing established commercial acceptability. This technology holds enormous potential to address a variety of energy storage applications, however the traditional chemistries used in primary alkaline batteries lead to irreversible degradation of the electroactive components which makes them unsuitable for the thousands of charge/discharge cycles desired for rechargeable grid-scale energy storage systems. UEP and the CUNY-EI have achieved several breakthroughs in addressing these challenges, utilizing chemical dopants and additives to stabilize both the Zn and MnO2 electrodes, which allow for more complete utilization of the battery capacity while maintaining hundreds to thousands of cycles.MnO2 and Zn deliver theoretical capacities, respectively, of 617mAh/g and 820mAh/g through a two-electron reaction in alkaline electrolyte (Figure 1). The theoretical energy density of this cell can be >400Wh/L, which is higher than many varieties of lithium-ion batteries. The Zn delivers its capacity through a dissolution-precipitation reaction, while MnO2 can exhibit solid-state proton insertion and dissolution-precipitation reactions depending on the type of MnO2 polymorph used. Electrolytic manganese dioxide (EMD, γ-MnO2), which is electrochemically synthesized in large quantities and used in primary batteries, exhibits proton insertion and dissolution-precipitation reactions. In batteries consisting of EMD, these two mechanisms each provide part of the two-electron capacity, where proton insertion delivers the first electron reaction (308mAh/g), and dissolution-precipitation delivers the second electron reaction. In contrast, birnessite(δ-MnO2), which has a layered crystal structure and is most commonly found in soils, exhibits only dissolution-precipitation reactions to deliver the two-electron capacity.The CUNY-EI made a breakthrough in 2014 and accessed the 2nd e- capacity of MnO2 reversibility. This was the first report of its complete reversibility for >6,000 cycles. EMD was used to make birnessite electrochemically in-situ, and also, because of ease of manufacturing, materials logistics and economic reasons. The additives, when mixed with EMD in the first discharge-charge formation process to make δ-MnO2, stabilized the layered cathode structure and prevented Mn3O4 formation. Bi2O3 prevented Mn3O4 formation electrochemically by complexing with the dissolved Mn(OH)6 3- and Mn(OH)4 2- ions. It also promoted δ-MnO2 formation in the charging process. The main discovery made at CUNY-EI involved recognizing that intercalating the MnO2 layers with Cu ions stabilized the cathode crystal structure and reduced the charge transfer resistance during the δ-MnO2’s electrochemical reactions. It was shown for the very first time in alkaline battery literature that energy densities approaching to 200Wh/L could be accessed from δ-MnO2 when paired with highly utilized Zn anodes.UEP’s current proton intercalation chemistry utilizes about 120-140 mAh/g-MnO2 and >160-200mAh/g-Zn. This creates an energy density of the cell of 150 Wh/L, which is comparable to existing lead-acid batteries, meaning UEP is competitive in many stationary battery applications including renewable integration, grid energy storage, backup power, including uninterruptible power supply (UPS), and residential backup applications. The company established a pilot scale manufacturing plant in Pearl River, NY with current production capacity of 100 MWh per year. Early production runs have gone to support battery systems for grid applications, backup power, and renewable integration projects. The batteries can be produced at cost lower than lead acid and lithium-ion batteries of comparable performance. Zn and MnO2 make up a small fraction of the cost per unit of storage capacity compared with costly or less environmentally friendly materials like cobalt, nickel, lithium, and lead that are used in other batteries. When manufactured in large volumes, UEP anticipates that its battery packs will cost less than $50’P3/kWh allowing building energy storage systems with a levelized cost of energy (LCOE) below the $0.05/kWh that ARPA-E has identified as the target for widespread adoption of energy storage on the electric grid. At $50/kWh, the technology becomes competitive for wide range grid applications including demand charge reductions, renewable load shifts and transmission and distribution upgrades. Moreover, these batteries offer a new level of inherent safety and environmental friendliness as they contain none of the flammable, toxic, or volatile electrolytes that have plagued other batteries considered for grid-scale storage. Figure 1