Alkaline Zn MnO2 Research Articles

Preparation of Mn/TiO2 catalysts using recovered manganese from spent alkaline batteries for low-temperature NH3-SCR

Black mass (BM) from spent alkaline Zn-MnO2 batteries was used for the first time as a Mn source in the preparation of Mn/TiO2 catalysts for low-temperature NH3-selective catalytic reduction (SCR) of NOx. To recover Mn species and eliminate alkali and Zn species, BM powder underwent DI-water washing, followed by carbothermal reduction. The resulting slags were further dissolved in HNO3, loaded onto TiO2 particles with ball milling, and then subjected to calcination. Nearly 100% of Zn species were removed from the BM via carbothermal reduction at 950 °C for 4 h with 5.0 wt% activated carbon. The resulting catalyst, derived from the treated BM, achieved similar NOx conversion (97%) as the catalyst prepared using a reagent-grade Mn chemical at 160 °C but a higher NOx-to-N2 conversion rate at 78%. The promoted N2 selectivity was attributed to a high Mn4+/Ti ratio and the presence of impurities from BM, such as Fe3+ ions, which enhanced oxidation ability of the catalyst. Conversely, insufficient removal of Zn or carbon additives in the slags led to a decreased Mn concentration, an increased proportion of Mn2+/Mn3+ species, increased surface OH groups, and reduced oxidation ability on the surface, thus reducing NOx conversion and N2 selectivity.

Characterizing Distribution and Morphology of ZnO Discharge Products in Commercial Alkaline Zn-MnO2 Batteries

During the discharge of alkaline Zn-MnO2 batteries, the dissolution of Zn particles in the anode saturate the electrolyte with zincate, prompting the formation of solid ZnO. Zincate is highly mobile in the electrolyte, giving rise to complex spatial distributions and morphologies of ZnO discharge products. The passivating behavior of ZnO is dependent on its distribution and morphology, as the active Zn particles within the anode must maintain a connection with the electronic network, while also having access to hydroxide ions from the electrolyte.1 Therefore, characterizing the factors that impact ZnO formation is critical to understanding how battery performance is impacted.2 Past attempts to model these batteries fail to adequately predict the behavior of Zn anodes under discharge conditions aimed at simulating real-world use cases.3 This work seeks to better characterize the behavior of Zn anodes in an effort to improve modeling capabilities based on experimental results.4 High resolution synchrotron CT was used to create in situ volumetric reconstructions of anodes from commercial AA and AAA batteries to determine ZnO morphology and radial distribution at various discharge conditions. Through a novel segmentation algorithm, quantitative data show a shift in ZnO radial distribution and microporosity depending on the rate and depth at which the anodes were discharged. High rate discharge leads to ZnO formation preferentially near the separator with a lower microporosity, increasing its passivating characteristics. Microporosity calculations show the discharge products form in two types, namely type I ZnO and ZnO hydrate. The latter type had only ever been reported on planar electrodes, yet it has a significant presence in commercial alkaline batteries discharged under certain conditions.4,5 In addition to a decreased microporosity, the morphology of ZnO also showed increased passivating characteristics when discharging using a continuous protocol. Shells of ZnO form around undischarged Zn cores during a continuous discharge, restricting hydroxide transport to the Zn surface and potentially isolating the core from the electronically conductive Zn network. When using a pulsed discharge protocol, ZnO formed distributed regions of microporous ZnO not adhered to undischarged Zn surfaces, leaving the remaining Zn in good contact with the electrolyte. Developing a more robust understanding of the factors that impact ZnO formation will enable more advanced models to be created. Acknowledgements This research was supported by funding from Energizer Holdings, Inc. We acknowledge collaborators Xiaotong Chadderdon, Matthew Wendling, Andrew Chihpin Chuang, and John Okasinski. This research also used resources of the Advanced Photon Source beamline 6-BM, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Methods for Tomographic Segmentation in Pseudo-Cylindrical Coordinates for Bobbin-Type Batteries.

High-resolution X-ray computed tomography (CT) has become an invaluable tool in battery research for its ability to probe phase distributions in sealed samples. The Cartesian coordinates used in describing the CT image stack are not appropriate for understanding radial dependencies, like that seen in bobbin-type batteries. The most prominent of these bobbin-type batteries is alkaline Zn-MnO2, which dominates the primary battery market. To understand material radial dependencies within these batteries, a method is presented to approximate the Cartesian coordinates of CT data into pseudo-cylindrical coordinates. This is important because radial volume fractions are the output of computational battery models, and this will allow the correlation of a battery model to CT data. A selection of 10 anodes inside Zn-MnO2 AA batteries are used to demonstrate the method. For these, the pseudo-radius is defined as the relative distance in the anode between the central current collecting pin and the separator. Using these anodes, we validate that this method results in averaged one-dimensional material profiles that, when compared to other methods, show a better quantitative match to individual local slices of the anodes in the polar θ-direction. The other methods tested are methods that average to an absolute center point based on either the pin or the separator. The pseudo-cylindrical method also corrects for slight asymmetries observed in bobbin-type batteries because the pin is often slightly off-center and the separator often has a noncircular shape.

High-Energy and Long-Lived Zn–MnO2 Battery Enabled by a Hydrophobic-Ion-Conducting Membrane

Alkaline Zn-MnO2 batteries feature high security, low cost, and environmental friendliness while suffering from severe electrochemical irreversibility for both the Zn anode and MnO2 cathode. Although neutral electrolytes are supposed to improve the reversibility of the Zn anode, the MnO2 cathode indeed experiences a capacity degradation caused by the Jahn-Teller effect of the Mn3+ ion, thus shortening the lifespan of the neutral Zn-MnO2 batteries. Theoretically, the MnO2 cathode undergoes a highly reversible two-electron redox reaction of the MnO2/Mn2+ couple in strongly acidic electrolytes. However, acidic electrolytes would inevitably accelerate the corrosion of the Zn anode, making long-lived acidic Zn-MnO2 batteries impossible. Herein, to overcome the challenges faced by Zn-MnO2 batteries, we propose a hybrid Zn-MnO2 battery (HZMB) by coupling the neutral Zn anode with the acidic MnO2 cathode, wherein the neutral anode and acidic cathode are separated by a proton-shuttle-shielding and hydrophobic-ion-conducting membrane. Benefiting from the optimized reaction conditions for both the MnO2 cathode and Zn anode as well as the well-designed membrane, the HZMB exhibits a high working voltage of 2.05 V and a long lifespan of 2275 h (2000 cycles), breaking through the limitations of Zn-MnO2 batteries in terms of voltage and cycle life.

Development of MnO2 Based Cathodes for Alkaline Batteries via Combinatorial Approach

A combinatorial study is carried out to develop new cathode compositions in alkaline Zn-MnO2 secondary batteries. MnO2 is modified with ternary additions using Bi2O3, Na0.7MnO2, and NiO. A library of thick film cathodes over a wide compositional range is synthesized via sputter deposition. Thick film cathodes are investigated both electrochemically and structurally. Structural studies show that thick film cathodes are largely amorphous in the as-deposited state but upon charge-discharge cycling, are crystallized into δ-MnO2, i.e. layered polymorph of MnO2. The thick film cathodes are evaluated with cyclic voltammetry and charge-discharge cycling. Two compositional regions are noted as significant in terms of useful cathodes for rechargeable batteries. Compositions rich in NiO yield quite a reliable cell performance which might be considered as cathode material for Zn-NiO batteries. More importantly, there was also a region where Mn and Na had similar proportions doped by Bi and Ni, e.g. Bi0.08Na0.39Ni0.09Mn0.44Ox, which might be made the basis for improved cathode for Zn-MnO2 batteries.

How to increase the potential of aqueous Zn-MnO2 batteries: The effect of pH gradient electrolyte

Non-rechargeable alkaline Zn-MnO2 batteries are dominating the primary battery market and are a promising candidate for secondary battery storage systems as well. However, these batteries suffer from low potential and poor rechargeability. Here, we report a rechargeable membrane-less amphoteric aqueous Zn-MnO2 battery with a 2.4 V open circuit potential. We have employed alkaline (KOH), acidic (H2SO4) and neutral (K2SO4) Pluronic F-127 hydrogels as electrolytes. By placing the anode in an alkaline environment but the cathode in an acidic environment, we have successfully widened the potential window in an aqueous medium avoiding hydrogen and oxygen evolution reactions. The obtained open circuit potential of as prepared amphoteric battery is stable for more than 25 h and 200 charge-discharge cycles.

Study on flexible thin air electrodes and electrochemical performance of LR6 size as well as pouch Zn-air cells

Manufacturing stable and thin air electrodes for flexible Zn-air batteries becomes increasingly important and remains challenge. Here, we report low-cost mechanical calendering to fabricate thin gas-diffusion layers (GDL), catalytic layers (CL) and then heat pressing together. Finally, cylindrical and other sizes of flexible air electrodes are produced without the use of commercially expensive carbon cloth or carbon papers. By assembling the flexible air cathodes with anode Zn-In-Bi alloy powders or Zn foils, alkaline gel electrolytes and membranes, two kinds of Zn-air cells are assembled for performance evaluation. Results reveal that the LR6 Zn-air cells show a capacity of 5300–5400 mAh and an energy density of 340 Wh·kg−1 at 100 mA, having a double discharge capacity compared to the same size alkaline ZnMnO2 cells. Under a high drain rate of 1000 mA, the capacity and utilization of the Zn alloy powder remain 2750 mAh and 372 mAh·g−1, respectively. The flexible pouch Zn-air cells exhibit excellent charge-discharge performance under conditions of each cycle with 10 min at 2 mA cm−2. The discharge voltage is maintained in the range of 1.25–1.30 V within 120 cycles while the charge voltage is 2.00–2.05 V. These results demonstrate that the thin air cathodes can satisfy the high bending requirements for cylindrical LR6 size cells and flexible pouch Zn-air cells, as well as have high mechanical stability and electrochemical performance. Electrochemical impedance spectroscopies of the air cathodes and Zn-air cells are also examined.

From spent Zn–MnO2 primary batteries to rechargeable Zn–MnO2 batteries: A novel directly recycling route with high battery performance

For the first time, spent Zn–MnO2 primary batteries are recycled to directly build rechargeable Zn–MnO2 batteries with a mixed solution of sulfuric acid and hydrogen peroxide as the leachate, which aimed to the efficient recovery of spent Zn–MnO2 primary batteries and the realization of high-powered rechargeable Zn–MnO2 batteries. After simple purification, the leached liquid is directly used as the working solution to prepare an electrolytic rechargeable Zn–MnO2 battery. The experimental results show that the performance of the recycling solution of the neutral Zn–MnO2 primary battery was better than that of the alkaline Zn–MnO2 primary battery, and both performed better than the solution prepared with chemically pure reagents. After optimizing the pH of the working solution and charging current, the obtained rechargeable Zn–MnO2 battery can provide an energy efficiency of 72.33 % ± 0.55, a coulombic efficiency of 90.17 % ± 0.71, and excellent cycle stability. These experimental results show that spent Zn–MnO2 primary batteries can be successfully recycled to prepare rechargeable Zn–MnO2 batteries, demonstrating very good application potential.

(Invited) Manganese Dioxide Positive Electrodes for Aqueous Zinc-Ion Batteries

Tremendous work has been made in a relatively short period of time on developing the rechargeable aqueous zinc-ion battery (ZIB). The ZIB using inexpensive/abundant raw active materials is a cheaper and safer alternative to Li-ion batteries (LIBs), particularly where portability is not of primary importance. The ZIB is also considered by many to be the most promising rechargeable zinc battery technology because it addresses many of the short-comings of traditional zinc battery chemistries. By using a near-neutral pH electrolyte as compared to a strong alkaline solution, cycling of the zinc metal electrode is improved drastically. The coulombic efficiency of zinc plating/stripping is increased and internal short circuits due to dendritic growth of zinc metal are suppressed. The slightly acidic (pH 4-6) electrolyte also allows for new reversible (de)intercalation mechanisms to occur at the positive electrode. This has led to the development of several novel classes of electrode materials which store zinc cations.One such electrode material which is capable of intercalating Zn2+ cations is manganese dioxide. Compared to the alkaline Zn-MnO2 battery in which both the zinc negative electrode and the manganese dioxide positive electrodes undergo conversion reactions, the chemistry of the ZIB is simplified. Zn2+ is stripped from the negative electrode and intercalates into the positive electrode during discharge. Upon charge, Zn2+ cations de-intercalate from the positive electrode active material and plate back onto the negative electrode as zinc metal. In this work, various forms of manganese dioxide were explored in detail for use as the positive electrode active material for zinc intercalation. Different crystal structures of MnO2 were studied and several additional factors, such as particle size and morphology were found to impact the performance of Zn2+ intercalation. The diffusion coefficients were calculated and each material was cycled in a zinc-ion battery to determine its suitability as a Zn2+ intercalation electrode in a near-neutral aqueous system. Through this structure-properties correlation, general material design rules can be drawn, guiding future R&D efforts on ZIB chemistry. Figure 1

An operando spatially resolved study of alkaline battery discharge using a novel hyperspectral detector and X-ray tomography.

An experimental technique is described for the collection of time-resolved X-ray diffraction information from a complete commercial battery cell during discharging or charging cycles. The technique uses an 80 × 80 pixel 2D energy-discriminating detector in a pinhole camera geometry which can be used with a polychromatic X-ray source. The concept was proved in a synchrotron X-ray study of commercial alkaline Zn-MnO2 AA size cells. Importantly, no modification of the cell was required. The technique enabled spatial and temporal changes to be observed with a time resolution of 20 min (5 min of data collection with a 15 min wait between scans). Chemical changes in the cell determined from diffraction information were correlated with complementary X-ray tomography scans performed on similar cells from the same batch. The clearest results were for the spatial and temporal changes in the Zn anode. Spatially, there was a sequential transformation of Zn to ZnO in the direction from the separator towards the current collector. Temporally, it was possible to track the transformation of Zn to ZnO during the discharge and follow the corresponding changes in the cathode.

Improving Cycle Life and Active Materials Utilization for Rechargeable Alkaline Zn–MnO2 Batteries

The increasing utilization of renewable power sources has highlighted the need for inexpensive and safe energy storage systems in the electrical grid to stabilize the inherent fluctuations of such sources. Rechargeable alkaline Zn–MnO2­ batteries are an especially promising candidate for grid-scale storage, with high theoretical volumetric energy density rivaling Li-ion systems, environmentally compatible materials, and a safe non-flammable aqueous chemistry. Historically, conventional Zn–MnO2 batteries have been limited to only tens of cycles due to formation of irreversible manganese oxide and zinc-manganese oxide species in the cathode, along with shape change and passivation of Zn in the anode. Ingale et al. [1] first showed that practical electrodes could obtain ~1000–3000 cycles when only a small fraction of the theoretical capacity of MnO2 and Zn was accessed during each cycle (e.g. ≤ 20% of the first MnO2 electron and ≤ 2.5% of Zn capacity). Due to the inexpensiveness of the materials and ease of manufacturing, these limited depth of discharge (DOD) Zn–MnO2 cells have already been commercialized at overall costs of ~$150-250/kWh.[2] This presentation will cover ongoing efforts to improve the cycle life and active materials utilization (i.e. energy density) in limited DOD Zn–MnO­2­ cells[3,4,5] using additives and alternatives to conventional electrode, electrolyte, and separator materials. Initial work in increasing cycle life has focused on the use of electrolyte additives and zincate blocking separators. For example, the electrolyte additive triethanolamine (TEA) demonstrated an almost 300% improvement in cycle life with higher average energy efficiency,[3] while increased cycle life was also obtained by using a zincate-impermeable ceramic NaSICON membrane.[4] More recent work has focused on improving the overall energy density of the system, such as by increasing the loading of active materials in the cathode and by attempting to increase the DOD of the Zn anode through the use of electrode formulations along with the application of zincate-blocking polymers. Various aspects of this work will be presented. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. Dr. Imre Gyuk, Energy Storage Program Manager, Office of Electricity Delivery and Energy Reliability is also thanked for his financial support of this project. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. [1] N.D. Ingale, J.W. Gallaway, M. Nyce, A. Couzis, S. Banerjee, J. Power Sources 276 (2015) 7–18. [2] S. Banerjee, Alkaline Zn-MnO2 Battery Development: A University-Private-Public Partnership, in Department of Energy Office of Electricity and Energy Reliability Peer Review, Santa Fe, NM, September 25-27th, 2018. https://eesat.sandia.gov/wp-content/uploads/2018/10/1_SanjoyBanerjee_Presentation.pdf [3] M. Kelly, J. Duay, T.N. Lambert, R. Aidun, J. Electrochem. Soc. 164 (2017) A3684–A3691. [4] J. Duay, M. Kelly, T.N. Lambert, J. Power Sources 395 (2018) 430–438. [5] I. Vasiliev, B.A. Magar, J. Duay, T.N. Lambert, B. Chalamala, J. Electrochem. Soc. 165 (2018) A3517–A3524.

Highly Reversible Reactions in Neutral Aqueous Zinc Battery Systems

Along with the rapid development of renewable energy storage such as wind and solar, the large-scale energy storage technologies are highly desired. Among different energy storage solutions, the rechargeable aqueous Zn-MnO2 batteries are very promising due to their low cost, high environmental benignity and high energy, potentially two times high of the lead-acid batteries. However, the widely investigated rechargeable alkaline Zn-MnO2 batteries suffer from limited depth of discharge (DOD), Zn anode passivation and dendrite, and limited cycle life. In this talk, we will introduce the use of mild aqueous-based electrolytes to address the above issues based on the greatly improved rechargeability of both MnO2 cathode and Zn anode in such systems.[1,2] We will also discuss our recent understanding on how to realize and maintain the highly reversible reactions for both zinc metal and cathodes by optimizing the electrolyte and electrode structures in optimal neutral aqueous electrolyte systems to realize the long-term cycling stability for their future practical applications in large-scale energy storage.

Control of the State of Primary Alkaline Zn–MnO2 Cells Using the Electrochemical Impedance Spectroscopy Method

The commercial primary alkaline zinc–manganese cells after current loads and thermal treatment are studied using electrochemical impedance spectroscopy. The components of electric circuits and spectrum data responding to the changes in the investigated samples are identified on the basis of the analysis of impedance spectra and model equivalent circuits. It is found experimentally that the capacity dispersion is a parameter sensitive to any effects on alkaline zinc–manganese cells. The model of the electrode–electrolyte interface is used to evaluate the endurance of primary cells at thermal action.

In Situ Investigation of Morphological Changes in Discharging Alkaline Zinc-Manganese Dioxide Batteries By Transmission X-Ray Microscopy

Alkaline Zn-MnO2 batteries are one of the most widely used battery chemistries. Significant research has been made to investigate the chemical processes in these batteries in an effort to prolong lifetime under high discharge rates. One promising candidate for this characterization is X-ray transmission microscopy (TXM), a technique which offers the ability to probe the internal structures of the battery, without dismantling the cell. In this work, we use an in-house TXM to take snapshots of commercially available AA alkaline Zn-MnO2 cells at a series of discharge rates and temperature conditions. As the cells discharge, morphological changes are tracked as MnO2 is reduced and Zn is converted to ZnO.

Electrochemically induced spinel-layered phase transition of Mn3O4 in high performance neutral aqueous rechargeable zinc battery

Mn3O4 is an electrochemically inactive in alkaline Zn–MnO2 battery. Here, we show that Mn3O4 shows superior electrochemical performance in mild aqueous zinc sulfate electrolytes. Mn3O4 can be a new cathode material for neutral aqueous rechargeable zinc battery. Results reveal that spinel Mn3O4 transforms to intermediate Mn5O8 and finally to Zn-birnessite. The initial charge cycle proceeds without participation of zinc ions, while zinc ions participate in the subsequent reaction. The intercalation of zinc ions into the interlamination of birnessite leads to the generation of Zn-birnessite in discharge process, accompanied by the reduction of Mn4+ to Mn3+. Our results demonstrate a new manganese oxide cathode with average Mn valence state lower than four for rechargeable zinc batteries.

On the Fly EIS Tracking of Rechargeable Alkaline Zn-MnO2 Batteries for Large-Scale Use

This talk will discuss electrochemical impedance spectroscopy (EIS) tracking of aqueous alkaline Zn-MnO2 cells cycled at 20% depth of discharge (DOD) based on cathode capacity. Shallow cycled alkaline batteries have previously been reported as cost effective and safe options for large-scale electrical storage.1-3 Periodically collected EIS data was used to fit a full battery model based on Voigt elements, and fitted parameters were tracked over time. These were used as a real-time diagnostic to assess performance and predict future performance in advance of any degradation of the cell voltage. The cell model was based on individual electrode models developed previously by Donne and co-workers for γ-MnO2 and Hampson and McNeil for Zn.4,5 Two prismatic cell builds were compared using electrodes fabricated by two different commercial sources with identical compositions. Both cell performance and EIS response were distinctly different between the electrode sources. The model provided an acceptable fit of the experimental data in both cases, as shown in Figure 1. The parameters of the model corresponded to physical phenomena, allowing an analysis of the performance difference despite the fact that all electrode fabrication variables could not be known unless provided by the commercial sources. The combined anode and cathode interfacial models were incorporated into a transmission line porous electrode, shown in Figure 2. Each anode + cathode fit involved a combined 15 parameters, which was the minimum number of parameters that would fit data for all cells in all states of charge. Performance analysis was accomplished by comparing a) the individual parameters, b) lumped parameters such as the RC time constants and RLC Q factors, and c) features of the cycling potential such as the discharge end voltage (DEV).6 Use of a reference electrode with EIS has been shown to be highly dependent on electrode placement.7,8 Battery EIS also faces a challenge in that electrodes may have similar capacity, while ideally the counter electrode should be non-limiting.9 We will address these factors and discuss steps taken to obtain repeatable data free of inductive loops caused by capacitive coupling with current collectors and electrode tabs.10 Experimental procedure The cycling profile used constant-current/constant-voltage (CCCV) taper charging and constant current (CC) discharging. The cycled capacity was 20% of the one-electron MnO2 capacity in the cathode. The CC discharge was completed in 4 hours. The CCCV charge had a 1% overcharge, with the same current as discharge and an upper voltage limit of 1.65 V. If this voltage limit was tripped, voltage was held at 1.65 V until the desired charge capacity was reached or current dropped to below 20% of the CC stage. Every tenth cycle the cell was paused after the OCV period following discharging, and an EIS measurement was performed. The EIS potential was the sampled OCV when EIS began, with an amplitude of 5 mV. Frequencies were scanned from 50 kHz to 20 mHz at a spacing of 10 points per decade. Upon completion the cell was CCCV charged as usual, there was a 10 minute OCV period, and another EIS measurement was performed in the charged state. Acknowledgement This work was supported by the National Science Foundation under Grant No.1332030 in the Small Business Technology Transfer Research (STTR) program. References N. D. Ingale, J. W. Gallaway, M. Nyce, A. Couzis and S. Banerjee, J Power Sources, 276, 7 (2015).S. A. Mehta, A. Bonakdarpour and D. P. Wilkinson, Journal of Applied Electrochemistry, 47, 167 (2017).J. W. Gallaway, C. K. Erdonmez, Z. Zhong, M. Croft, L. A. Sviridov, T. Z. Sholklapper, D. E. Turney, S. Banerjee and D. A. Steingart, Journal of Materials Chemistry A, 2, 2757 (2014).J. B. Arnott, G. J. Browning and S. W. Donne, J Electrochem Soc, 153, A1332 (2006).N. A. Hampson and A. J. S. McNeil, J Power Sources, 15, 61 (1985).M. E. Orazem and B. Tribollet, Electrochim Acta, 53, 7360 (2008).S. Klink, E. Madej, E. Ventosa, A. Lindner, W. Schuhmann and F. La Mantia, Electrochem Commun, 22, 120 (2012).S. Klink, D. Hoche, F. La Mantia and W. Schuhmann, J Power Sources, 240, 273 (2013).A. Battistel, M. Fan, J. Stojadinovic and F. La Mantia, Electrochim Acta, 135, 133 (2014).B. W. Veal, P. M. Baldo, A. P. Paulikas and J. A. Eastman, J Electrochem Soc, 162, H47 (2015). Figure 1

Mn3O4/carbon nanotube nanocomposites recycled from waste alkaline Zn–MnO2 batteries as high-performance energy materials

Alkaline zinc manganese dioxide (Zn–MnO2) batteries are widely used in everyday life. Recycling of waste alkaline Zn–MnO2 batteries has always been a hot environmental concern. In this study, a simple and cost-effective process for synthesizing Mn3O4/carbon nanotube (CNT) nanocomposites from recycled alkaline Zn–MnO2 batteries is presented. Manganese oxide was recovered from spent Zn–MnO2 battery cathodes. The Mn3O4/CNT nanocomposites were produced by ball milling the recovered manganese oxide in a commercial multi-wall carbon nanotubes (MWCNTs) solution. Scanning electron microscopy (SEM) analysis demonstrates that the nanocomposite has a unique three-dimensional (3D) bird nest structure. Mn3O4 nanoparticles are homogeneously distributed on MWCNT framework. Mn3O4/CNT nanocomposites were evaluated as an anode material for lithium-ion batteries, exhibiting a highly reversible specific capacitance of ~580 mAh·g−1 after 100 cycles. Moreover, Mn3O4/CNT nanocomposite also shows a fairly positive onset potential of −0.15 V and quite high oxygen reducibility when considered as an electrocatalyst for oxygen reduction reaction.

Recovery of zinc and manganese, and other metals (Fe, Cu, Ni, Co, Cd, Cr, Na, K) from Zn-MnO2 and Zn-C waste batteries: Hydroxyl and carbonate co-precipitation from solution after reducing acidic leaching with use of oxalic acid

The article discusses the current situation of the spent batteries and portable accumulators management. It reviews recycling technologies of the spent batteries and portable accumulators which are used in the manufacturing installations in the world. Also, it presents the authors’ research results on the reductive acidic leaching of waste material of the zinc-carbon batteries (Zn-C) and zinc-manganese batteries (alkaline Zn-MnO2) delivered by a company dealing with mechanical treatment of this type of waste stream. The research data proved that the reductive acidic leaching (H2SO4 + C2H2O4) of the battery’s black mass allows to recover 85.0% of zinc and 100% of manganese. Moreover, it was found that after the reductive acidic leaching it is possible to recover nearly 100% of manganese, iron, cadmium, and chromium, 98.0% of cobalt, 95.5% of zinc, and 85.0% of copper and nickel from the solution with carbonate method. On the basis of the results, it is possible to assume that the carbonate method can be used for the preparation of manganese-zinc ferrite.

A facile chemical route for recovery of high quality zinc oxide nanoparticles from spent alkaline batteries

Recycling of spent domestic batteries has gained a great environmental significance. In the present research, we propose a new and simple technique for the recovery of high-purity zinc oxide nanoparticles from the electrode waste of spent alkaline Zn–MnO2 batteries. The electrode material was collected by the manual dismantling and mixed with 5M HCl for reaction with a phosphine oxide reagent Cyanex 923® at 250°C for 30min. The desired ZnO nanoparticles were restored from the Zn-Cyanex 923 complex through an ethanolic precipitation step. The recovered particle product with about 5nm diameter exhibited fluorescent properties (emission peak at 400nm) when excited by UV radiation (excitation energy of 300nm). Thus, the proposed technique offered a simple and efficient route for recovering high purity ZnO nanoparticles from spent alkaline batteries.

Preparation and Stability Research of Ago As Cathode Material

Silver-zinc battery (AgO/Zn) is regarded as an energy storage system with advantages of high energy density, high power density and superior rate capability when compared with Ni-MH and lithium battery systems. Due to its relatively high cost, AgO/Zn batteries are widely employed in the field of underwater devices, fish torpedo and aerial/space applications. nanoscaled AgO with high purity was synthesized by a chemical precipitation method, and found this method suited to industrialized production. the electrode offers a discharge voltage plateaus of 1.3-1.58V, a discharge capacity of above 393 mAh·g−1 at 8 C rate ,and an exciting specific power density much higher than the current level for existing secondary batteries and super capacitors. As a cathode material for AgO/Zn battery, AgO suffers severely from its poor thermal stability. During long-term storage, AgO decomposes and generates Ag2O and Ag, which in return fasten the decomposition process of AgO. As a result, decomposition issue for AgO even occurs at room temperature. To the best of our knowledge, there is few study regarded to the thermal stability of AgO and no mature fabrication process for AgO has been reported. Na2SiO3, well-know inhibiter, is widely used in alkaline Zn-MnO2 battery to improve stability of the battery. However, there is no systematic investigation of using Na2SiO3 as stability agent in AgO/Zn system. Herein, the effects of Na2SiO3 on the thermal stability and electrochemical performance of AgO are elucidated. Through aging treatments, it is concluded that with the introduction of Na2SiO3, the decomposition degree of AgO at room temperature has been reduced to some extent. However, the decomposition temperature of AgO remains unchanged. On the other hand, electrochemical performance of AgO/Zn battery is degraded with addition of Na2SiO3 in the cathode material due to the poor conductivity of Na2SiO3. The results showed that 10 min later after the injection of KOH electrolyte into the cell model, Na2SiO3 mainly influences discharge voltage at early stage when discharging the cell at 4 C with voltage cut-off at 1.0 V. The discharge voltage drop at early stage increases significantly with increasing the amount of Na2SiO3. The open circuit voltage of the AgO with 2wt% Na2SiO3 as cathode was 1.6 V and the voltage suddenly dropped to 1.18 V after the current was applied. The discharge voltage for the AgO with 10.7wt% Na2SiO3 as cathode drastically dropped to 0.2 V under the same test condition. Interestingly, the discharge voltage turned out to be almost identical after discharging for 20 s for all the cells with different weight ratio of AgO as cathodes. These results indicates that the introduction of Na2SiO3 in the AgO cathode mainly influence solution equilibrium.