Secondary batteries with multivalent ions for energy storage

Rechargeable aqueous batteries have gained significant attention as a promising alternative to conventional lithium-ion systems, particularly for grid-level energy storage applications. This growing interest is driven by several key advantages, including superior safety, low cost, environmental compatibility, and the potential for sustainable large-scale production. Historically, lead-acid and alkaline rechargeable batteries have represented iconic examples of aqueous systems, playing pivotal roles in both stationary and portable energy storage. However, recent advancements have led to the exploration of diverse aqueous battery systems that rely on aqueous electrolytes incorporating alkali or multivalent metal ion salts. These systems include lithium-ion aqueous batteries (Li-ion aqueous), zinc-ion batteries (ZIBs), and aluminum-ion batteries (AIBs), each offering unique advantages.A fundamental challenge in aqueous battery technology arises from the complexity introduced by the solvent itself—water. Due to its protic nature, water allows for proton-coupled electron transfer (PCET) reactions, which are commonly overlooked. Understanding these proton-coupled processes is crucial for developing aqueous batteries with high efficiency and long cycle life. Therefore, it becomes essential to differentiate between charge storage mechanisms involving protons and those relying on the reversible insertion of alternative charge carriers, such as lithium ions or multivalent cations. Such differentiation is critical not only for accurately determining the origin of stored charge but also for optimizing battery performance by minimizing parasitic reactions, such as hydrogen evolution or material dissolution.Here, we will present a rigorous and systematic electrochemical methodology to unambiguously reveal reversible proton-coupled charge storage mechanisms using a diverse selection of model electrodes. These include inorganic materials such as TiO₂ and MnO₂, organic compounds like quinone-based electrodes, and metal-organic frameworks exemplified by Prussian Blue. Furthermore, we will demonstrate how to elucidate charge storage mechanisms in aqueous electrolytes containing alternative charge carriers, examining the interplay between proton-coupled processes and the insertion of other ionic species. This multifaceted analysis will not only address the critical question of the proton source within the aqueous electrolyte, but also highlight the impact of proton-coupled charge storage on the formation and evolution of local pH gradients. By systematically investigating these phenomena, we aim to provide a comprehensive understanding of how proton-coupled electron transfer reactions contribute to charge storage across a range of material chemistries.

Chapter 9 - Rechargeable Batteries and Their Management

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

The World's energy consumption has increased drastically over the past several decades, particularly driven by increasing population and economic activities as well as rising living standards with technological advancements. Since the industrial revolution, fossil fuels have been the major source of energy productions, which is today shown as the primary cause of the ongoing climate change and associated environmental challenges in threatening the existence of many living species and human life and comfort. According to the statistics provided by International Energy Agency (IEA),1 the global energy supply was 14 282 Mtoe in 2018 that is 115% higher than that of the value for 1973. Fossil fuels, such as natural gas, coal and oil are still playing a critical role and covering more than 80% of global energy demands. The concerns associated with global warming and depletion of energy sources have been directing the attention to renewable and environmentally-benign energy solutions. However, efficient, affordable, and nature-friendly energy storage systems are the key to using renewable energy sources effectively. In this study, a comprehensive literature search is conducted to study and bibliografically evalute Canada's energy storage research and development activities over the last five decades. The present study intends to present the cumulative picture on energy storage reseach and development efforts and assess how universities, research institutes and funding agencies have contributed to this particular field. The literature search compiles a total of fifty-year data on energy storage-related research and development activities conducted in Canada. The number of conducted studies associated with energy storage regarding research articles, books, research projects, dissertations, and patents is presented in the period from 1971 to 2021. Furthermore, the Canadian institutes are ranked based on their scholarly ouputs and publications to indicate the most productive ones in the field of energy storage based on the data presented in the literature sources. Energy storage is described as the capture of harvested energy for later use to maintain the balance fluctuations between energy demand and supply. As the world moves towards a low-carbon economy, energy storage systems are exepcted to even play a more critical role in extracting more energy from renewable resources.10 The intermittent characteristic of renewable resources, specifically solar and wind, is one of the major challenges ahead of a reliable and steady renewable energy supply. This can be avoided by storing excess energy to re-use when the renewable resources are not sufficient or unavailable. Energy storage systems can be categorized in different ways in regards to the form of converted and stored energy. Figure 1 presents an overview of energy storage system categories which are considered in this study. It is important to note that chemical energy storage allows to storage and transportation of large amounts of energy for long distances with minimal self-discharge rates, which is crucial for the distribution and effective use of renewable energy resources. Figure 2 presents the energy density of various chemical fuels and batteries. Despite possessing high energy density, environmental concerns associated with the production and consumption of fossil-based chemical fuels, e.g. diesel, gasoline or natural gas, should be adrressed. In regards to nature-friendly chemical energy storage, particularly power-to-gas chemical storage, hydrogen is attracting favorable attention nowadays. In this regard, hydrogen appears to be the lightest and most abundant chemical element in the universe, but is not available freely (by itself). However, it occurs naturally within a compound such as water (H2O); therefore, it is an intermediate energy form. Excess electricity from renewables can be utilized in hydrogen production processes, i.e. electrolysis of water, to store energy in chemical form. Power-to-hydrogen chemical energy storage is a unique and clean method, and it can be compatible with electrochemical storage since hydrogen possesses much greater energy content. One of the major challenges with hydrogen is the low calorific value per unit of volume (MJ/m3) due to its low density. This can be avoided by deploying alternative hydrogen carriers, such as ammonia. Liquefaction at atmospheric conditions, high hydrogen atom content and high energy density characteristics make ammonia a favorable medium for storage and transportation of energy. It is further to note that batteries and capacitors are devices allowing electrochemical storage of electricity. The potential energy is stored in chemical form in batteries, while capacitors are expected to store their potential energy in the form of an electric field.14 Batteries are thus most commonly used and matured options that propose high energy densities and voltages. Lithium-ion (Li-ion), sodium-sulphur (NaS), nickel-cadmium (NiCd), lead acid (Pb-acid), lead-carbon batteries, zebra batteries (Na-NiCl2) and flow batteries are the existing battery types used in various applications. Due to their high specific energy (per unit weight) and high specific energy (per unit volume), lithium batteries attract considerable attention in electrical energy storage. Capacitors can be classified as electrostatic capacitors, electrolytic capacitors, and electrochemical capacitors, among which electrochemical, so-called supercapacitors, promote the highest capacitance per unit of volume owing to a porous structure 15. As a mechanical energy storage method, pumped hydro accounts for more than 95% of the global installed energy storage capacity.15 The main advantage of mechanical energy storage is to readily deliver energy. The method is easy to adapt for conversion and storage of energy from various sourcessuch as water current, wave, or tidal. Pumped hydro, compressed air, and flywheel are the commonly practiced mechanical energy storage methods. Pumped hydro and compressed air are bound to specific geographical characteristics, which is the main restriction for the implementation of these energy storage methods. A flywheel stores the energy obtained from a rotor mass spinning at very high speeds as kinetic energy. The stored kinetic energy can be later used to produce electricity by altering the angular velocity of the flywheel through a decelerating torque and using an electric motor in reverse 16. Despite of being non-suitable for long-term energy storage, flywheels offer favorable advantages, that is, long-life spin, high energy densities and low maintenance costs, and fast charging.17 Thermal energy storage (TES) systems are effective systems to store heat in a reservoir for a period of time (defined or undefined) for later use, that is, space heating and cooling, electricity production, hot water. If the reservoir temperature is kept under the atmospheric temperature, the storage process is called cold thermal energy storage.18 Operating temperature range, capacity requirements, charging and discharging requirements are some of important parameters when choosing an appropriate TES system for a desired application. Since the major proportion of produced and consumed energy is heat around the world, TES systems carries a significant weight regarding the development of effective energy systems . Furthermore, energy losses from the systems commonly occur in the form of heat. Decreasing losses via further utilizing from waste energy is one of many way to mitigate environmental impacts, which can be accomplished by implementing TES systems in a cost effective manner. In the current study, an overview of Canada's energy storage related studies from 1971 to 2021 is presented. The scope of this study is to present the contributions of Canadian universities, research institutes and funders to energy storage research and development efforts over the last five decades. The keywords and methodology that are used for the literature search are depicted in Figure 3. The collected and compiled data for the corresponding fields are presented in figures, and results are discussed in the following sections. In this study, an online literature search is conducted on Canada's energy storage related studies over the last five decades. The current section presents collected and compiled data in charts. The findings of the conducted study are discussed in detail. The most productive institutes of Canada regarding conducting or sponsoring energy storage-related studies are presented. The documents associated with energy storage in all subject areas are presented in Figure 4. In this regard, the highest number of energy storage-related studies were conducted in the subject area of engineering in Canada from 1971 to 2021. The fields of energy and chemistry appear as the other two major subject areas in which high number of energy storage research was conducted. While compiling data, attention has been paid to any potential field conflicts concerning the multi attribution of interdisciplinary publications. Therefore, it should be noticed that chemistry may have an impact on the subject areas of biochemistry, genetics, and molecular biology. The same impact of engineering could be seen on the subject area of energy. The data collected and analysed for comparative evaluation reveals that the Canadian institutes have produced 37 386 energy storage-related academic research publications over the last 50-year period. In this regard, Figure 5A presents the breakdown of energy storage-related publications affiliated to Canada in the corresponding material types in accordance with the publication years. Figure 5A shows that studies in this field consistently increases every year. Consequently, the year 2020 appears as the most productive one in this regard as of April 2021. In the light of this trendline, predicting that the year 2021 will be more productive than 2020 would not be wrong. Figure 5B has been prepared as a heat map to show Canada's provinces where energy storage-related studies were conducted over the last 50 years. In this regard, Ontario appears as the most productive province of Canada in terms of scholarly publications. However, one has to keep in mind that Ontario has the highest number of contributing institutes/universities compared to the rest of the provinces in Canada. Figure 6 presents the breakdown of the number of energy storage-related books, book chapters, and editorials in accordance with publication years in Canada. The year 2018 was the most productive year of Canada by producing 200 documents in the corresponding classification. The other important point that should be pinned in the figure is the year 2005. Compared to the previous year, almost five times more energy storage-related books were published in 2005. Compared to 2019, the number of published books decreased almost by half in 2020. The impact of COVID-19 is recognized as one of numerous reasons behind this result. The number of energy storage-related dissertations completed in Canada over the last five decades is primarily searched through and collected from Library and Archives Canada. The search results are, in this regard, presented in Figure 7. It can be noted that the data presented in Figure 7 is based on the number of energy storage-related theses available in the library; and thus, the results are subject to change in accordance with instantaneous new data entry to the library. As of April 2021, there are 626 energy storage-related MSc and PhD theses/dissertations entered in the online system of Library and Archives Canada. The highest number of theses/dissertations was recorded in the year of 2013 with a value of 62. Based on data collected from the website of Canadian Intellectual Property Office, the number of energy storage-related patents of Canada is 11 719 for the last 50 years. The corresponding results are presented Figure 8. According to this, the year of 2018 appeared to be the Canada's most productive year in terms of patents registered under the title of energy storage. Canada is blessed with institutions that have been supporting energy storage-related research and developments by providing funds. Over the evaluated period of 50 years, the Natural Sciences and Engineering Research Council of Canada (NSERC) appears as the major funding agency for Canada's energy storage related research, development, partnership, strategic innovation and commercialization efforts and has supported more than 8500 projects in the field of energy storage. A total number of projects that have been funded by Canadian institutes have become 18021 from 1971 to 2021. It is most likely to observe a major increase in the number of projects by the impact of the recent hydrogen strategic plan of Canada. Being an excellent energy storage medium is one of many advantages of hydrogen. Therefore, there is a significant correlation in between hydrogen and energy storage research efforts. The subject matter report is already named as call-to-action for green hydrogen transition for the energy sector. In the report, the importance of dedicating more domestic resources to green hydrogen efforts to achieve the targets by 2050 is emphasized clearly (Figure 9). The development and implementation efforts of effective, affordable, and nature-friendly energy storage systems are recognized as a key requirement in achieving a green energy transition. In this regard, Canada intends to be the country leading and inspiring many others. Figure 10 shows the a number of Canadian institutes/universities that have produced more than 100 scholarly publications on energy storage under the subject area of energy. According to this, the total number of such scholarly publications has been 9125 over the past five decades. The results clearly show that there are two universities, such as University of Waterloo with 809 publications and Ontario Tech. University (formerly University of Ontario Institute of Technology) with 697 publications, leading in this particular area. University of Waterloo appears as the most productive Canadian university with a total number of 809 publications while Ontario Tech. University, which is one of the Canada's youngest universities, follows with a total number of 697 publications. The specific affiliations in the publications show that the researchers working in the productive environment of Clean Energy Research Laboratory (CERL) at Ontario Tech. have played a major role in this achievement. The data that support the findings of this study are available in Scopus, Library and Archives Canada and Canadian Intellectual Property Office with the reference number of [17], [18], and [19], respectively. These data were derived from the following resources available in the public domain: https://www.scopus.com/search/form.uri?display=basic&zone=header&origin, https://www.bac-lac.gc.ca/eng/services/theses/Pages/search.aspx, https://www.ic.gc.ca/opic-cipo/cpd/eng/search/basic.html?wt_src=cipo-patent-main.

Large-scale energy storage is of significance to the integration of renewable energy into electric grid. Despite the dominance of pumped hydroelectricity in the market of grid energy storage, it is limited by the suitable site selection and footprint impact. Rechargeable batteries show increasing interests in the large-scale energy storage. However, the challenging requirement of low-cost materials with long cycle and calendar life restricts most battery chemistries for use in the grid storage. Recently we developed a new generation of rechargeable hydrogen gas batteries by exploiting catalytic hydrogen evolution/oxidation reactions as the anode, which offers negligible overpotentials, high rates and stable electrochemical performance. In this talk, I will introduce some exciting rechargeable hydrogen gas battery chemistries, including novel nickel-hydrogen gas, proton-hydrogen gas, chlorine-hydrogen gas, and among others. The excellent stability and low cost of the rechargeable hydrogen gas batteries demonstrate attractive characteristics for large-scale energy storage.

Metal displacement batteries (MDBs), or liquid metal batteries, are an emerging technology with significant potential in providing high capacity, low-cost energy storage solutions, capable of addressing many of the challenges associated with storing energy from renewable sources. The key characteristic of metal displacement batteries is that at least one of the electrodes is in liquid state and a molten salt is used as an electrolyte. Since its original proposal in the 1960’s liquid metal batteries have re-emerged in recent years and different battery chemistries and designs have been explored, including Ca-Bi, Na-Sb, and many others [2,10]. Recently, Na-Zn liquid metal batteries have been studied as an alternative to other configurations, showing significant potential in achieving good performance for large-scale energy storage, while avoiding the high cost associated with some electrode materials such as Nickel or Lithium [7,8]. In past years, alternatives to all-liquid cells have emerged in the form of designs where the cell materials are a mixture of solids and liquids. Examples of this include the commercially available Zebra battery, where a Na-NiCl electrode pair is used [1,6]. These designs offer some of the advantages of all-liquid cells, while simultaneously mitigating many of the disadvantages of handling and operating a very high temperature system. Na-Zn have also been proposed for solid cathode designs, taking advantage of the lower cost of Zn over Ni [4,3].The cathode in these designs is composed of a porous structure, within which multiple chemical species can co-exist. Electrolyte components share the space with metal deposits,salt crystals, and other electrochemical reaction products. As a result, the micro-porous structure of this composite system is an important factor in determining the performance of the cell, as the spatial distribution of different materials can have an impact on the effective conductivity of the electrode [5,9]. The porous structure hosts complex multi-component mass transfer phenomena as well, potentially having an impact on the mass-transfer overpotential of the cell.This work aims to study the impact of the microstructural properties of the solid electrode in a liquid displacement battery, and their importance to the effective conductivity of the system. We have developed a computational tool that enables us to create randomized microstructures in 3D, representing the electrode-electrolyte assembly. We are able to preserve the desired physical characteristics by using target pore-size distributions and volume fraction input as seed parameters. We use this tool to generate representative structures and analyze their effective bulk conductivity by solving Laplace’s equation over the resulting domain, accounting for the different local conductivity of each material.This methodology is applied to a novel Na-Zn cell in order to assess the importance of the pore-scale properties of the cathode, as well as its material components, including solid Zn metal, solid NaCl deposits, and molten salt components. It is expected that different material arrangement configurations will induce heterogeneous current distributions in this system. Furthermore, the ionic composition of the electrolyte would be different at different charge levels, leading to additional variation through its charge/discharge cycle.Using this methodology, the range of different electrode phase configurations produced during operation can be studied in the absence of microstructure imaging data. A representative elementary volume for the Zn electrode assembly is analyzed to determine the best approach for up-scaled performance predictions of the Na-Zn cell. With this method, it is possible to acquire data to elucidate desirable or undesirable electrode structure properties of this system, providing insight which can be used for improving manufacture and operation of the cell. [1] Dustmann. “Advances in ZEBRA batteries”. J. Power Sources (2004).[2] Kim et al. “Liquid metal batteries: Past, present, and future”. ChemicalReviews (2013).[3] Lu et al. “An Intermediate-Temperature High-Performance Na-ZnCl2 Bat-tery”. ACS Omega (2018).[4] Lu et al. “Liquid-metal electrode to enable ultra-low temperature sodium-beta alumina batteries for renewable energy storage”. Nature Communications(2014).[5] Qiu et al. “Pore-scale analysis of effects of electrode morphology and electrolyteflow conditions on performance of vanadium redox flow batteries”. J. PowerSources (2012).[6] Sudworth. “The sodium / nickel chloride ( ZEBRA ) battery”. J. Power Sources (2001).[7] Xu et al. “Electrode Behaviors of Na-Zn Liquid Metal Battery”. Journal ofThe Electrochemical Society (2017).[8] Xu et al. “Na-Zn liquid metal battery”. Journal of Power Sources (2016).[9] Zhang et al. “Progress in 3D electrode microstructure modelling for fuel cellsand batteries: transport and electrochemical performance”. Progress in Energy(2019).[10] Zhang et al. “Liquid Metal Batteries for Future Energy Storage”. EnergyEnvironmental Science (2021). Figure 1

Effective CuO/Cu7S4 nanospheres heterostructures for advanced “rocking-chair” zinc-ion battery

Rechargeable battery technologies have ignited major breakthroughs in contemporary society, including but not limited to revolutions in transportation, electronics, and grid energy storage. The remarkable development of rechargeable batteries is largely attributed to in-depth efforts to improve battery electrode and electrolyte materials. There are, however, still intimidating challenges of lower cost, longer cycle and calendar life, higher energy density, and better safety for large scale energy storage and vehicular applications. Further progress with rechargeable batteries may require new chemistries (lithium ion batteries and beyond) and better understanding of materials electrochemistry in the various battery technologies. In the past decade, advancement of battery materials has been complemented by new analytical techniques that are capable of probing battery chemistries at various length and time scales. Synchrotron X-ray techniques stand out as one of the most effective methods that allow for nearly nondestructive probing of materials characteristics such as electronic and geometric structures with various depth sensitivities through spectroscopy, scattering, and imaging capabilities. This article begins with the discussion of various rechargeable batteries and associated important scientific questions in the field, followed by a review of synchrotron X-ray based analytical tools (scattering, spectroscopy, and imaging) and their successful applications (ex situ, in situ, and in operando) in gaining fundamental insights into these scientific questions. Furthermore, electron microscopy and spectroscopy complement the detection length scales of synchrotron X-ray tools and are also discussed toward the end. We highlight the importance of studying battery materials by combining analytical techniques with complementary length sensitivities, such as the combination of X-ray absorption spectroscopy and electron spectroscopy with spatial resolution, because a sole technique may lead to biased and inaccurate conclusions. We then discuss the current progress of experimental design for synchrotron experiments and methods to mitigate beam effects. Finally, a perspective is provided to elaborate how synchrotron techniques can impact the development of next-generation battery chemistries.

Flexible electronics have been limited by inadequate energy storage solutions. Despite extensive research, the energy efficiency and lifespan of current flexible storage devices fall short of commercial standards. Additionally, the high cost of these solutions hampers the scalability of flexible electronics. Flexible batteries offer a promising energy storage solution, leveraging the success of commercial batteries. While flexible lithium-ion batteries have been investigated, their intrinsic safety hazards limit their broader adoption, particularly in wearable and medical electronics. Flexible zinc-ion batteries have recently garnered attention for their safety, high capacity, and low cost. However, challenges such as shuttling effects, zinc dendrites, and low energy efficiency remain. Although advancements have been made in electrodes, electrolytes, and separators for flexible zinc-ion batteries, further research is needed before they can achieve commercial viability. This thesis investigates the materials and structural design of flexible aqueous zinc-ion batteries, focusing on methodologies to enhance reaction kinetics and lifespan for potential industrial applications. We first introduce a hydrogel cellulose paper-based separator that integrates seamlessly with electrode materials, facilitating the rapid and straightforward fabrication of large-area flexible zinc-ion batteries, thus supporting scalable production. The hydrogel-reinforced cellulose paper also provides excellent mechanical durability, addressing the issue of repeated bending and enhancing the overall robustness of paper batteries. In the next chapter, we introduce a layer-expanding strategy to enhance electrodes for aqueous zinc-ion batteries by increasing active sites and facilitating smooth hydrated zinc ion transport. The insertion of n-butylamine expands the interlayer spacing of Zr(HPO4)2•H2O (α-ZrP), creating expanded-interlayer ZrP (EI-ZrP). EI-ZrP is also proved to facilitate electron transport. By combining hydrogel cellulose paper (HCP) as the separator, a paper battery with EI-ZrP in the cathode material is fabricated and proved to be efficiently relieved from shuttling effects. Furthermore, zinc-air batteries, which use atmospheric oxygen at the cathode, reduce material costs and show immense potential for flexible energy storage applications due to their high capacity and low production cost. This thesis introduces an innovative double-layer electrolyte design that leverages the distinct kosmotropism of different anions to induce phase separation, eliminating the need for a separator. This design enhances zinc utilization and battery lifespan by mitigating side reactions and provides a framework for further advancements in zinc-air batteries and their cost-effective, scalable production. All proposed solutions for cellulose-based zinc-ion batteries have been demonstrated through integration with practical electronic devices, validating their capability for prolonged use. These experiments offer valuable insights into industrial applications of flexible cellulose-based batteries in wearables, medical devices, and other flexible electronics.

In-situ XRD study of the structure and electrochemical performance of V2O5 nanosheets in aqueous zinc ion batteries

Aqueous zinc ion batteries (ZIBs) are becoming increasingly popular as a new form of resource for electrochemical energy storage due to their high safety, affordability, availability of natural zinc resources, and high gravimetric energy density. However, the development of high-performance ZIB cathode materials remains a great challenge because current ZIB cathode materials tend to have low conductivity and relatively complex energy storage mechanisms. Compared with other cathode materials, ammonium vanadate-based materials have been extensively investigated as cathode materials for ZIBs due to their plentiful availability and high potential capacity. In this review, we highlight the mechanisms and challenges of ammonium vanadate-based materials and summarize the progress in improved strategies including the design of different morphologies, doping with different impurities, the introduction of different intercalators, and combination with other materials for high-performance ZIBs. Finally, the paper also provides an outlook on the future challenges and development prospects of ammonium vanadate-based cathode materials in ZIBs.

Unravelling the proton hysteresis mechanism in vacancy modified vanadium oxides for High-Performance aqueous zinc ion battery

With increased concerns about fossil fuel depletion and carbon dioxide emissions, renewable power generation from solar and wind sources is a promising solution for meeting our increasing need of energy. However, with renewable power there is a principal issue of power availability to match the demands. Therefore, inexpensive, long life and high-rate- capable energy storage systems are needed.Iron based alkaline batteries are a promising candidate for large scale energy storage due to its low cost and abundance of raw material, long cycle life and high theoretical energy density of iron electrodes. [1] Despite these advantages, historically, iron electrodes have had low charging efficiency due to the hydrogen evolution reaction, and low utilization rate and poor rate capability due to the non-conducting nature of the discharge product. [2] In this study, a sintered iron electrode with high charging efficiency, high utilization rate and long cycle life is presented.The iron electrode in this study was prepared by loading carbonyl iron on to a degreased nickel mesh and sintering under inert atmosphere. The iron electrode was then tested in a three-electrode configuration with two sintered nickel-oxide counter electrodes and a mercuric oxide reference electrode was used for electrode potential measurements. Sodium sulfide was added into the electrolyte to prevent passivation.After the initial formation cycles, the utilization rate of the sintered iron electrode stabilized at 0.23 Ah/g. About 80% of this value was realized at C rate (Figure 1). This type of performance is very promising for large-scale energy storage applications since the high rate capability is necessary for rapid load-leveling. Following initial characterization of capacity, the electrodes were subjected to charge/discharge cycles with C/2 rate over 500 cycles without any significant change in capacity. The average faradaic efficiency during this high rate cycling is above 96% (Figure 2).The properties of long cycle life and high faradaic efficiency are expected to lower the cost of implementing and operating iron-based energy storage systems. The future work of this study is focused on understanding the role of electrode design parameters (porosity, thickness and pore utilization) and sulfide additives on the performance of the iron electrode. Acknowledgement The research reported here was supported by the U.S. Department of Energy ARPA-E (GRIDS program, DEAR0000136), the Loker Hydrocarbon Research Institute, and the University of Southern California.

This paper reports the design, fabrication and characterization of a hybrid energy storage system, with a textile based rechargeable zinc-ion battery connected in parallel with a textile supercapacitor. The proposed devices were implemented on polyester-cotton textiles with a polymer separator integrated within the textile. The cathode and anode of the zinc-ion battery and the supercapacitor’s carbon electrodes were fabricated with low cost materials via spray deposition. The proposed hybrid energy storage system achieved an areal capacity of 46.6 μAh.cm^−2 at 1 mA.cm^−2 discharge current within the potential window of 1.9 V to 0.9 V.

Conversion-type reactions based battery chemistry presents a great promise for next-generation energy storage. It is based on using the chemical reaction (also called chemical transformation) of the working ion to store energy, different than intercalation-type reactions as used in today’s Li-ion batteries. Good examples include Li-S, Li-O2, and broadly speaking metal electrodes (Li, Mg, Zn, etc.). Interfaces generally play a more crucial role in these battery chemistry systems because of the complexity of this type of reaction even though each of the systems has its unique characteristics. This not only includes electrode/electrolyte interfaces, but also the interfaces within the electrode materials. Here, we use two examples of battery chemistry to demonstrate how the manipulation of interfaces can promote the conversion-type reactions for energy storage: Mg chemistry and Li-S chemistry. In Mg battery chemistry, due to the divalent nature of Mg2+, the ion transport kinetics in solid host materials is limited. Therefore, the development of Mg battery has been limited by poor performance of electrode materials. We have developed two conversion-type electrode materials with improved Mg2+ storage performance: SnSb alloys for anode1 , 2 and V2O5 nanoclusters for cathode.3 More importantly, our experimental and theoretical modeling reveal that the interfaces between the multicomponent phases generated during repeated magnesiation–demagnesiation is responsible for the improved performance of SnSb; a surface-controlled reaction of Mg2+ and V2O5, denoted as a molecular energy storage mechanism, improves the reaction kinetics which increases the rates and capability. In Li-S battery chemistry, control of solution chemistry and nucleation of polysulfides (on cathode host surface) is crucial for improved capacity and cycling stability. We have demonstrated that, through tuning the solubility of polysulfides in electrolytes, an improved cycling stability is achieved. The controlled nucleation of polysulfides on carbon nanofiber surface leads to the formation of a unique porous microsphere structure of Li2S. This unique porous Li2S microsphere enables a close to 100% utilization of S (specific capacity >1600mAh/gS); it also decreases the passivation of cathode. This opens up a new avenue for Li-S R&D of using low surface area carbon host materials, thus a great potential for high pack density and low electrolyte/sulfur ratio in Li-S cells. In this talk, we will present our understanding on these interface-related conversion-type reactions and recent progress of material innovation that improves device performance. New electrode architecture engineering will also be discussed. 1. Y. W. Cheng, Y. Y. Shao, L. R. Parent, M. L. Sushko, G. S. Li, P. V. Sushko, N. D. Browning, C. M. Wang and J. Liu, Adv. Mater., 2015, 27, 6598-6505. 2. L. R. Parent, Y. W. Cheng, P. V. Sushko, Y. Y. Shao, J. Liu, C. M. Wang and N. D. Browning, Nano Lett., 2015, 15, 1177-1182. 3. Y. W. Cheng, Y. Y. Shao, V. Raju, X. L. Ji, B. L. Mehdi, K. S. Han, M. H. Engelhard, G. S. Li, N. D. Browning, K. T. Mueller and J. Liu, Advanced Functional Materials, 10.1002/adfm.201505501, 2016.