Rechargeable Battery Systems Research Articles

3D-Structured Metal Oxide/Sulfur Composites for High Performance Lithium-Sulfur Batteries

The lithium-sulfur (Li-S) system is one of the promising rechargeable battery systems for energy storages and electrification of vehicles due to a high theoretical capacity and energy density, as well as the low cost and availability of non-toxic sulfur. However, polysulfide dissolution is the main limitation to the stability of the Li-S system. Here, we tackle this challenge by synthesizing 3D-structured graphene and porous silica materials with a pomegranate-like architecture through a simple chemical reactions, which is subsequently loaded with sulfur to form a 3D-graphene-sulfur composite (denoted as S@G composite). Furthermore, a thin layer (~100 nm) of tungsten oxide (WO3) on the S@G composite dramatically improves the cycling performance of the Li-S system with an initial capacity of 1425 mAh/g and approximately 95% capacity retention after 500 cycles. The porous silica/sulfur composite cathodes exhibit excellent electrochemical performances including a high specific capacity of 1450 mAh g-1, a reversible capacity of 82.9 % after 100 cycles at a rate of C/2 (1 C = 1672 mA g-1) and an extended cyclability over 300 cycles at 1 C-rate. Through the analysis and the theoretical calculation, results provide a novel material and approach to enhance the electrochemical performance of rechargeable Li-S batteries and sheds light on developing high-performance energy storage devices for a variety of applications.

(Invited) Designing New Electrolytes for High-Energy Lithium Metal Batteries

Lithium (Li) metal batteries with conventional nickel-rich transition metal oxide cathodes have been regarded as one of the next-generation high-energy rechargeable battery systems because the Li metal anode has an ultrahigh theoretical specific capacity (3860 mAh g-1) and a very low standard electrochemical redox potential (-3.040 V). However, two major problems associated with Li metal anode ¾ Li dendrite growth during repeated cycling and low Li Coulombic efficiency still hinder the application of rechargeable Li metal batteries, although great progresses have been made in stabilizing Li metal anode in the past decade, including smoothening Li deposition morphology and increasing Li Coulombic efficiency. Among these progresses, the development of novel electrolytes is one of the most important things, which can not only enable Li metal anode to reach high Li Coulombic efficiency of 99.5%, but also stabilize high voltage cathodes up to 4.5 V. In this presentation, the designing principles of solvating solvents and diluents in a new class of electrolytes called localized high-concentration electrolytes for high-energy Li metal batteries will be reported. The mechanisms for the performance advancements by the new electrolytes will also be discussed, especially through the Li/electrolyte and cathode/electrolyte interphases.

Probing the electrode-solution interfaces in rechargeable batteries by sum-frequency generation spectroscopy.

An in-depth understanding of the electrode-electrolyte interaction and electrochemical reactions at the electrode-solution interfaces in rechargeable batteries is essential to develop novel electrolytes and electrode materials with high performance. In this perspective, we highlight the advantages of the interface-specific sum-frequency generation (SFG) spectroscopy on the studies of the electrode-solution interface for the Li-ion and Li-O2 batteries. The SFG studies in probing solvent adsorption structures and solid-electrolyte interphase formation for the Li-ion battery are briefly reviewed. Recent progress on the SFG study of the oxygen reaction mechanisms and stability of the electrolyte in the Li-O2 battery is also discussed. Finally, we present the current perspective and future directions in the SFG studies on the electrode-electrolyte interfaces toward providing deeper insight into the mechanisms of discharging/charging and parasitic reactions in novel rechargeable battery systems.

The Rise of Prussian Blue Analogs: Challenges and Opportunities for High‐Performance Cathode Materials in Potassium‐Ion Batteries

Potassium‐ion batteries (PIBs) are emerging as one of the potential alternatives to lithium‐ion batteries for next‐generation rechargeable battery systems. Nevertheless, the lack of suitable cathode materials with high capacity hinders their practical applications. Recently, Prussian blue analogs (PBAs) cathode materials stand out as promising candidates for PIBs. Their unique crystal structure with open 3D frameworks and large interstitial voids favors fast K+ intercalation without causing drastic volume expansion, which is the prerequisite for high‐rate and long‐term battery operation. Herein, a fundamental review on the development and advance of PBAs cathode materials is presented for PIBs with in‐depth elucidation of their crystal structures, chemical compositions, and electrochemical performances. Particularly, the unique and prominent advantages of PBAs in both aqueous and nonaqueous PIBs are highlighted. In addition, to bridge the current gap from the laboratory to future commercialization, potential improvement strategies are proposed to overcome the present drawbacks. Finally, perspectives and new insights are provided for further exploration and research in PBAs for better PIBs.

A layered titanium-based transition metal oxide as stable anode material for magnesium-ion batteries

Rechargeable magnesium (Mg) battery with high volumetric energy density is one of the most promising candidates for next-generation safe and clean renewable energy sources. Just like rechargeable lithium battery, the development of anode materials beyond metal Mg will greatly promote the practical process of rechargeable Mg battery system. In this study, we propose a strategy to realize the reversible storage of Mg2+ in possible zero-strain layered transition metal oxides (Li2TiO3) via nanotechnology for the first time. The as-prepared layered Li2TiO3 anode shows good cycling stability with a highly reversible Mg2+ storage capacity of 110 mA h g−1. The unusual Mg storage mechanism with stable phase transition reaction is proposed by various ex situ analyzing and testing techniques which will help advance the development process of the long-life rechargeable Mg batteries.

Designing High-Voltage and Large-Capacity Battery Packs for Fuel-Cell Hybrid Railroad Propulsion System

Due to the problem of global warming caused by greenhouse gas emissions, internal combustion engines in a lot of transportation systems are being electrified. For the railroad propulsion system, it is essential to apply a high-voltage/large-capacity energy source in order to ensure that the system operates properly. Thus, fuel-cell and rechargeable battery systems are being considered nowadays. The battery system can receive and store all regenerative energy to improve energy efficiency. In addition, since the battery pack of a propulsion system utilizing a hydrogen fuel-cell requires continuous charging/discharging, regardless of the railroad vehicle’s driving profile, the battery pack is designed to ensure its stable use and to minimize maintenance costs. Consideration should be given to the characteristics of railroad vehicles. In this research, a hydrogen fuel-cell hybrid railroad vehicle propulsion system specification, which has been studied recently, was applied to study the considerations in the design of high-voltage/large-capacity battery packs for railroad vehicles. In particular, the passive and active cell-balancing circuit and an algorithm for the stable management of battery packs for hybrid railroad vehicles in which a continuous charging/discharging operation is repeated are proposed and verified through experiments.

Biomimetic 3D Fe/CeO2 decorated N-doped carbon nanotubes architectures for high-performance lithium-sulfur batteries

lithium-sulfur (Li-S) batteries have been regarded as one of the most promising systems for next-generation rechargeable batteries owing to their high energy density and low cost. However, the “Shuttle effect” of polysulfides and low sulfur utilization upon cycling are still hindering their practical applications. Herein, we report a series of marine organism-like hollow nanoarchitecture consisting of nitrogen (N) doped 1D carbon nanotubes (CNTs), which were derived from binary Fe/Ce Prussian blue analogs (PBAs) and melamine. This nitrogen-doped 3D hollow scaffold offers large inner space (ф ≈ 200 nm) and sufficient electric conducting for insulating sulfur and provides adsorption sites for immobilizing polysulphides. The introduced double metal species enable strong chemical adsorption toward polysulfides and could facilitate the redox reaction between sulfur and polysulphides. When applied in Li-S batteries, the as-prepared materials showed a high capacity of 1241 mAh g−1 and a stable cycling performance (1003 mAh g−1 after 100 cycles) at a current density of 0.2 C. The enhancement of electrochemical activity could be attributed to the 3D hollow architecture of the hybrid, in which the nitrogen-doping generates defects and active sites for improved interfacial adsorption. This work could inspire developing biomimetic architectures for high-performance Li-S batteries.

Waste Pd/Fish-Collagen as anode for energy storage

Because of the huge demand for energy materials, it is paramount to develop practical, low-cost, and renewable energy systems. Until now, batteries made of green materials have either been costly or of limited use. Herein, this paper reports the pioneer utilization of fish waste, doped with Pd nanoparticles (Pd NPs) by incipient wetness impregnation to form Pd/Fish-Collagen. The Pd/Fish-Collagen was first used as a catalyst to abate benzene, and then utilized as anode material in three different rechargeable battery systems; Li-, Na-, and Mg- ion batteries. XRD patterns confirmed that the Fish-Collagen (CaS and CaCO3) was amorphous, while the Pd/Fish-Collagen sample exhibited broad peaks assigned to a mixture of Pd and PdO NPs coexisting with the amorphous Fish-Collagen. TEM and HRTEM images confirmed that the Fish-Collagen and the Pd NPs had average particle sizes of about 70 and 5 nm respectively. The electrochemical properties of the Pd/Fish-Collagen as an anode material in Li, Na, and Mg-based cells showed reversible capacities of 270, 120, and 105 mA h g−1, respectively. The CV and ex-situ XRD tests suggested a pseudocapacitance reaction occurred in Li and Na storage, while the Mg-based cells presented a conversion reaction. This new strategy to generate electrodes from renewable sources is cost-effective and with optimization, millions of tons of this remaining waste can find potential applications in such energy storage systems.

Development and challenges of aqueous rechargeable zinc batteries

With the rapid consumption of fossil energy resources and the increasing pollution problems, the efficient use of energy and the development of renewable energy sources is urgently needed, which demand for the large-scale electrical energy storage system with properties of high-security, low-cost, environmentally benign, remarkable capacity and long-life span. In this regard, achieving some breakthroughs in this system will have extremely important strategic impacts on future energy structure adjustments and smart grid construction. Although lithium ion battery has dominated the energy market for decades, the intrinsic drawbacks of high cost and safety issues, to a great extent, impedes its utilization in scale-up energy storage system. And recent years witnessed the significant progress of rechargeable multivalent metal ions batteries, such as Mg2+-ion, Al3+-ion, Ca2+-ion and Zn2+-ion batteries. With the unique features of high safety, low-cost, environmental friendly, abundant resources stockpile, low redox potential (–0.76 V vs. SHE), high capacity (up to 820 mAh g–1 theoretically) and energy density (5851 mAh mL−1) of metallic Zn as well as remarkable ionic conductivity of aqueous electrolyte, aqueous rechargeable zinc battery has attracted plenty of interest in recent years and exhibits great potential to be an important candidate for the next generation of high-safe and large scale energy storage system. Many researchers have paid great attention to the development of high performance aqueous rechargeable zinc battery system, including cathode materials, electrolytes and anode. And some great achievements have been obtained. Henceforth, in this review, we have systematically reviewed the research progress of aqueous rechargeable zinc battery, summarized and discussed the existing problems faced by this system and the related solutions. Based on the author’s best knowledge and understanding of aqueous rechargeable zinc battery, we have looked forward to its future research direction and made some perspectives, which is expected to pave the pathway for the understanding and further development of aqueous rechargeable zinc battery. In our view, the development of advanced solid/gel electrolyte should be attached great significance, which is a promising way to solve a series of problems existing in anode and cathode, such as cathode material dissolution, zinc anode dendrite growth, passivation and corrosion, as well as the by-products existing in the system. Moreover, the research on solid/gel electrolyte also offers some opportunities of constructing wearable and flexible electronic devices, such as smart watch, which is greatly beneficial to put forward to the practical application of aqueous rechargeable zinc battery. In addition, development of high performance cathode materials with remarkable strength of both high-voltage and high-capacity, and in-depth researches on the modification and optimization of zinc anode are the further trends of high-performance aqueous rechargeable zinc battery.

CTAB-capped copper nanoparticles coated on N doped carbon layer and encapsulated in ZIF-67: a highly-efficient ORR catalyst

The development of cathode materials with high cost-effectiveness, reliable performance, and good oxygen reduction activity are important to develop the next generation rechargeable metal-air battery system. Herein, we have developed a novel technique for synthesizing a catalyst with superior activity and durability for oxygen reduction reaction (ORR). Porous carbon with doped Cu nanoparticles was prepared by pyrolyzing Cu-containing ZIF-67 (Cu/ZIF-67). The findings show that Cu0.5%/Co-NC-900 exhibits superior ORR performance with an onset potential (Eo) of 0.98 V and a half-wave potential (E1/2) of 0.85 V, superior to all other prepared as well commercial Pt/C (20 wt.%, Eo 0.96 V and E1/2 0.82 V) catalysts in an alkaline solution. The excellent ORR performance of Cu0.5%/Co-NC-900 is due to the synergistic contribution to gradual mass transfer of Cu, Co and N doping structure, high pyridine content, and porous multilayer structure. This novel and rational metal doping strategy will dramatically enhance electrocatalyst operation and provide a template for new metal-doped porous carbon or catalyst designs.

Stabilizing zinc metal anodes by artificial solid electrolyte interphase through a surface ion-exchanging strategy

With rapid development of large-scale grid storage system, aqueous Zn batteries with features of superior safety, low cost and high energy density have attracted a growing number of researchers. However, severe corrosion and dendrite growth of Zn anodes have hindered their cycling performance and commercial application. Here, we fabricated an indium-based protective layer on Zn metal surface via a facile ion-exchange route. The insulating indium-based compounds provide necessary potential gradient to induce Zn plate underneath the coating film. Meanwhile, indium and its derivatives can effectively suppress corrosion and regulate Zn plating behavior due to unique physical and chemical properties. The symmetric cells with In-coated Zn anodes maintain stable stripping/plating process over 1400 h. Improved performance of full cells with modified Zn anode paired with α-MnO2 cathode can be achieved. Our work provides a simple and convenient approach to upgrade corrosion-resistant technology of rechargeable aqueous battery systems.

(Invited) Layered Sodium Transition Metal Oxides As Cathode Materials for Na-Ion Batteries

Thanks to their excellent electrochemical performance, Li-ion batteries have been successfully utilized as a power source in electric vehicles and large-scale energy storage systems. However, there are some concerns that the current technology of Li-ion batteries is not able to meet the demands for power sources in future energy storage applications. For example, lithium resources are expensive and too geographically constrained, leading to a substantial increase in the cost of Li-ion batteries. In this connection, new rechargeable battery systems such as sodium ion, sodium metal, magnesium, metal-air, and metal-sulfur batteries are being considered as alternatives to replace Li-ion batteries. In particular, Na-ion batteries have attracted rapidly increasing attention owing to the low cost of Na-ion batteries.1-3 Because of their low cost, the main potential application of Na-ion batteries is considered to be large-scale energy storage systems. However, it should be stressed that it is not easy to reduce the cost of Na-ion batteries relative to that of Li-ion batteries, in spite of the inexpensive Na precursors. The current Na-ion batteries have slightly lower energy densities than Li-ion batteries. This implies that the cost per energy ($/Wh) of Na-ion batteries cannot be easily reduced because the energy density limitations offset the cost savings due to the use of Na. Therefore, it is necessary to develop high capacity electrode materials to improve the energy density of Na-ion batteries.In this presentation, we will focus on our recent works involving the development of high capacity layered-structured sodium transition metal oxide cathode materials to improve the energy density of Na-ion batteries. We have examined various layered Na1-xMO2 (M = Mn, Fe, Ni, and their solid solution analogues) materials, along with understanding the role of dopants in the reaction mechanisms of those electrode materials. We also discuss the failure mechanisms of those cathode materials and suggest a strategy for improving electrochemical performance.[1] Y. Kim, K.-H. Ha, S. M. Oh, K. T. Lee, Chem. Eur. J., 20 (2014) 11980.[2] S. Y. Hong, Y. Kim, Y. Park, A. Choi, N.-S. Choi, K. T. Lee, Energy Environ. Sci., 6, (2013) 2067.[3] M.-S. Kwon, S. G. Lim, Y. Park, S.-M. Lee, K. Y. Chung, T. J. Shin, K. T. Lee, ACS Appl. Mater. Interfaces, 9 (2017) 14758.

Sulfur Infilled Carbon Nanospheres As Cathode Materials for Lithium–Sulfur Batteries

To date lithium-ion (Li-ion) batteries have been the de facto commercial battery type used in consumer electronics as well as in the first generation of electric vehicles (EVs). However, increases in the practical energy density of Li-ion batteries are too sluggish to keep pace with the demands of the next generation of portable electronics and EVs. Lithium Sulfur (Li–S) batteries are one of the most promising “beyond Li-ion” rechargeable battery systems in terms of both cost and specific energy density. (1, 2) Li–S batteries can deliver a practical specific energy density of 600 Wh/kg, which is more than double the values offered by state-of-the-art Li-ion batteries. (3, 4) However, there are still issues, which need to be addressed before widespread commercialization of Li–S batteries can be possible. Sulfur (S) and lithium sulfide (Li2S) have intrinsically low electronic conductivity. (5) Furthermore, the high-order lithium polysulfides (Li2Sx (6 < x ≤ 8)), which are formed upon first lithiation, are highly soluble in the standard liquid Li–S battery electrolyte. These various polysulfide anions are mobile and can be partially reduced and oxidized multiple times in the vicinity of the anode and cathode, respectively, leading to a so-called polysulfide shuttle phenomenon. (6) Additionally, the large volume changes (80%) which are associated with conversion reactions can lead to electrode disintegration and electrical isolation issues, resulting in severe capacity decay. (7) Various methods have been explored in an attempt to tackle these detrimental issues. Sulfur-carbon composites have been investigated to improve conductivity, following the pioneering work of the Nazar Group. (8) Efforts to reduce the polysulfide shuttle have been made via the application of various polysulfide-trapping interlayers, the use of functional separators and the exploitation of solid-state electrolytes.In this work, we detail the preparation of carbon nanospheres (CNS) with application as conductive sulfur host materials for Li–S batteries. CNS are prepared via facile hydrothermal treatment with different cost-effective precursors and the influence of each precursor on the structural and physical properties of the nanospheres is determined through examination of electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy and gas adsorption data. The electrochemical performance of sulfur infilled CNS samples is evaluated through comparison of cyclic voltammetry and galvanostatic cycling data. We demonstrate that the choice of carbon precursor can have a significant influence on the performance of the CNS-based sulfur electrodes. Sulfur infilled CNS materials, which are morphologically similar, can have significantly different electrochemical response due to differences in their physical properties such as pore volume and pore structure.

(Energy Technology Division Graduate Student Award Address sponsored by Bio-Logic) Understanding Charge Transport for Current and Future Electrochemical Energy Storage Technologies

Advances in electrochemical energy storage are key for the integration of intermittent wind and solar energy sources into the grid, widespread adoption of electric vehicles, and development of new safe and reliable consumer devices. For grid, transportation, and electronic energy storage markets, each application has distinct needs. Therefore, developing battery technology for emerging and wide-spread applications demands greater understanding of the complex chemical and electrochemical processes that occur within rechargeable batteries. Electron transfer and ion transport are the foundation of battery function where the capacity, loaded voltage and current define the practical energy and power delivery of the system. During operation, repetitive addition and removal of electrons and ions can lead to structural change within the electrode and interfacial formation that can dramatically impact electrochemical outcomes. Thus, structural, chemical, and electrochemical characterization during operation is critically important for next generation electrochemical energy storage technologies. The research efforts highlighted in this talk use multiple advanced characterization techniques, including operando based methods, to probe charge transport properties, structural changes, and interfacial evolution in multiple rechargeable battery systems. Specifically, X-ray absorption spectroscopy enabled structure and oxidation state elucidation in the absence of long-range order. Isothermal microcalorimetry was used to determine heat evolution due to parasitic or decomposition reactions operando. X-ray diffraction was employed to track temperature-induced and lithiation-induced phase changes of distinct electroactive materials. Using advanced characterization, these research efforts provide insight into electron transfer and ion transport properties and their impact on application relevant outcomes (resistance, cycle life, delivered capacity) of electrochemical energy storage technologies.

Alloy Anode Materials for Rechargeable Mg Ion Batteries

AbstractRechargeable magnesium ion batteries are interesting as one of the alternative metal ion battery systems to lithium ion batteries due to the wide availability and accessibility of magnesium in the earth's crust. On the one hand, electrolyte solutions in which Mg metal anodes are fully reversible are not suitable for the use of high voltage/high capacity transition metal oxide cathodes due to complex surface phenomena. On the other hand, Mg metal anodes cannot work reversibly in conventional electrolyte solutions in which high voltage/high capacity Mg insertion cathodes can work because of passivation phenomena that fully block them. Replacing Mg metal with alternative anodes that can work reversibly in conventional electrolyte solutions could provide a promising route to elaborate high voltage and high capacity rechargeable Mg battery systems. Herein, the recent progress in alloy anodes based on group IIIA, IVA, VA elements is summarized. The theoretical evaluations, achievable capacities, synthetic strategies, battery test configurations, electrochemical properties, and underlying reaction mechanisms are systematically summarized and discussed. The key issues and challenges impeding their current use are identified and some valuable suggestions for their future development as practical reversible anodes for Mg batteries are provided.

Water as a catalyst for ion transport across the electrical double layer in ionic liquids

It was previously shown experimentally that the ionic liquid (IL) system based on 1-ethyl-3-methylimidazolium dicyanamide $([{\mathrm{C}}_{2}\mathrm{mim}][\mathrm{dca}])$ outperforms $N$-butyl-$N$-methylpyrrolidinium dicyanamide $([{\mathrm{C}}_{4}\mathrm{mpyr}][\mathrm{dca}])$ as an electrolyte in a rechargeable zinc battery. Specifically, $[{\mathrm{C}}_{2}\mathrm{mim}][\mathrm{dca}]$ requires a lower overpotential to initiate electrodeposition of zinc, enables a higher zinc deposition peak current density, and supports a greater number of charge-discharge cycles. In the present work, a set of molecular dynamics simulations of two IL systems (i.e., IL + 9 mol % Zn + 3 wt % water) reveals that these differences could be related to the overscreening and crowding phenomena that exist in these IL systems. Furthermore, the work reveals the most likely mechanism by which water acts as an electrochemical catalyst in transferring metal cations to a negatively charged electrode. This transfer is a necessary step for subsequent metal deposition, as required for a rechargeable battery system, for example. In particular, the results of the simulations reveal three primary findings. First, it is shown that water activates the transfer of zinc onto the negative electrodes by temporarily disrupting zinc's [dca] coordination shell while zinc is located within the interfacial region; second, it is shown that the transfer of zinc is obviously greater in the $[{\mathrm{C}}_{2}\mathrm{mim}][\mathrm{dca}]$ system than in the $[{\mathrm{C}}_{4}\mathrm{mpyr}][\mathrm{dca}]$ system, which is consistent with experimental measurements; and third, when the effects of crowding are largely eliminated in the $[{\mathrm{C}}_{4}\mathrm{mpyr}][\mathrm{dca}]$ system (i.e., when the layering instability and the anion layer collapse in the anodic interfacial region are avoided by the use of a smaller electrode charge), the zinc transfer dynamics are completely changed and the $[{\mathrm{C}}_{4}\mathrm{mpyr}][\mathrm{dca}]$ system starts providing a more favorable environment for zinc transfers. These findings present a significant advance in the understanding of the electrode-electrolyte interface in ILs.

Spinel rGO Wrapped CoV2O4 Nanocomposite as a Novel Anode Material for Sodium-Ion Batteries.

Binary mixed transition-based metal oxides have some of the most potential as anode materials for rechargeable advanced battery systems due to their high theoretical capacity and tremendous electrochemical performance. Nonetheless, binary metal oxides still endure low electronic conductivity and huge volume expansion during the charge/discharge processes. In this study, we synthesized a reduced graphene oxide (rGO)-wrapped CoV2O4 material as the anode for sodium ion batteries. The X-ray diffraction analyses revealed pure-phased CoV2O4 (CVO) rGO-wrapped CoV2O4 (CVO/rGO) nanoparticles. The capacity retention of the CVO/rGO composite anode demonstrated 81.6% at the current density of 200 mA/g for more than 1000 cycles, which was better than that of the bare one of only 73.5% retention. The as-synthesized CVO/rGO exhibited remarkable cyclic stability and rate capability. The reaction mechanism of the CoV2O4 anode with sodium ions was firstly studied in terms of cyclic voltammetry (CV) and ex situ XRD analyses. These results articulated the manner of utilizing the graphene oxide-coated spinel-based novel anode-CoV2O4 as a potential anode for sodium ion batteries.

Dual-confined SeS2 cathode based on polyaniline-assisted double-layered micro/mesoporous carbon spheres for advanced Li–SeS2 battery

Selenium-sulfur solid solutions (SexSy) attracts soaring attention owing to its improved electrical conductivity over sulfur and higher theoretical specific capacity than selenium. Herein, high-performance lithium-selenium/sulfur batteries with a dual-confined cathode configuration by encapsulating SeS2 in double-layered hollow micro/mesoporous carbon spheres (DSMCs) with a conductive polyaniline (PANI) protection sheath are proposed. Polysulfides/polyselenides are efficiently restricted in the cathode via physical and chemical entrapment from DSMCs and PANI as well as chemical binding between selenium and sulfur. Benefiting from the distinct advantages of SeS2 and the well-constructed host framework, the cathode achieves high capacity utilization of 1018 mAh g−1 at 0.2 A g−1, together with outstanding rate capability of 619 mAh g−1 at 2 A g−1 and excellent cycle life over 500 cycles with almost 100% Coulombic efficiency. The novel SexSy-based cathode demonstrates a promising route to surmount some bottlenecks of current lithium-sulfur systems for high-performance rechargeable batteries.

Aqueous based dual-electrolyte rechargeable Pb–Zn battery with a 2.8 V operating voltage

Abstract A novel rechargeable PbO2-Zn battery system using Zn as negative and PbO2 as positive electrodes in a KOH-H2SO4 dual-electrolyte is developed. Using a bi-polar ion exchange membrane that effectively prevents the H+ and OH− from neutralization, the positive and negative electrodes operate in the respective electrolytes with different pH. The Zn electrode provides a low potential of −1.3 V in KOH solution and the PbO2 has a high potential of +1.5 V in H2SO4 solution. This resulted in a cell operating voltage of 2.8 V in an aqueous electrolyte. The system also demonstrated a high rate performance and good rechargeability. This simple, low-cost system not only overcomes the thermodynamic limit of water decomposition and achieves a high voltage aqueous based battery, but also provides a new approach in design of future electrochemical devices.

Investigating the Electrocatalysis of a Ti3C2/Carbon Hybrid in Polysulfide Conversion of Lithium-Sulfur Batteries.

Despite the fact that lithium-sulfur batteries are regarded as promising next-generation rechargeable battery systems owning to high theoretical specific capacity (1675 mA h g-1) and energy density (2600 W h kg-1), several issues such as poor electrical conductivity, sluggish redox kinetics, and severe "shuttle effect" in electrodes still hinder their practical application. MXenes, novel two-dimensional materials with high conductivity, regulable interlayer spacing, and abundant functional groups, are widely applied in energy storage and conversion fields. In this work, a Ti3C2/carbon hybrid with expanded interlayer spacing is synthesized by one-step heat treatment in molten potassium hydroxide. The subsequent experiments indicate that the as-prepared Ti3C2/carbon hybrid can effectively regulate polysulfide redox conversion and has strong chemisorption interaction to polysulfides. Consequently, the Ti3C2/carbon-based sulfur cathode boosts the performance in working lithium-sulfur batteries, in terms of an ultrahigh initial discharge capacity (1668 mA h g-1 at 0.1 C), an excellent rate performance (520 mA h g-1 at 5 C), and an outstanding capacity retention of 530 mA h g-1 after 500 cycles at 1 C with a low capacity fade rate of 0.05% per cycle and stable Coulombic efficiency (nearly 99%). The above results indicate that this composite with high catalytic activity is a potential host material for further high-performance lithium-sulfur batteries.