Rechargeable System Research Articles

Effect of managed aquifer recharge on drawdown cone in plain area of Linqing City, China

The Yellow River flood plain in northern of China, affected by the low precipitation and the large amount of well irrigation, is facing the ecological problems of serious groundwater overdraft and expansion of drawdown cone area. Taking Linqing city of Shandong Province as an experimental area, the technical scheme and parameters of Open channel-Underground perforated pipe-Shaft groundwater recharge system were designed by combining theoretical calculation and field test, and the effect of recharge was observed and analyzed. The results show that this project has increased groundwater amount of 52310.82m3 by water diversion for 7 days compaired with existing canal system, accounting for 60.7% of the total groundwater recharge. This recharge technology can effectively increase the amount of groundwater replenishment and raise the groundwater table as well as scope of groundwater recharge. It has the advantages of no energy consumption, no land occupation, rechargeability, and drainage. Thus, it is of great significance to the recovery of groundwater drawdown cone area and the comprehensive treatment of drought and waterlogging.

Electric Vehicle Model Based on Multiple Recharge System and a Particular Traction Motor Conception

The transportation systems around the world are drastically going electrified as a trend because of inevitable heed being paid towards global warming caused by carbon dioxide emissions. A variety of equipment is contained inside these modern versions of the electrified vehicles, and many appear to be similar in types. The internal electric motor and battery power used in these designs are largely responsible for their robustness and durability in transportation systems. The energy conservation problem, on the other hand, is a vital factor that must be handled in order to ensure overall performance and cost-effectiveness. This paper provides a thorough examination of the internal equipment needed to facilitate and optimize the transportation system’s energetic global success with these critical parameters. In the present study, a specific investigation is emphasized which mainly aims to recognize a new electric motor within the propulsion system. The same type of machine is discussed by elaborating internal designing through the implementation of the corresponding mathematical model and along with the corresponding electronic inverter. The associated control system is also established and implemented. Therefore, a significant theoretical contribution, made in this paper, can be used to examine the performance of a particular electrical machine for EV applications. A robust FOC-based control application confirmed this analysis. When a vehicle’s power needs to be increased rapidly, this one-of-a-kind electrical machine proves its worth. Using the MATLAB simulation method, the robustness of this system’s control has been demonstrated in this special mode.

A study of water infiltration basin and clogging using column experiments

The clogging of infiltration basins is the main problem affecting the proper functioning of groundwater artificial recharge systems. In this study, several parameters have been varied to understand their impacts on water infiltration. The experimental results show that the effect of initial humidity is significant for less porous material such as silty soil (Hamri) and sand. The air bubbles are also an important factor to take into consideration since when trapped within porous structures, it forms a barrier for the displacement of water infiltration. The accumulation of suspended particles in stormwater can contribute to clogging by creating a light layer due to the finest particles, which remain in suspension for a long time. Finally, for the tested materials and experimental conditions, we observed that a combination of a silty soil and sand layer in the design of infiltration basins was more practical than a combination of sand and gravel. The latter, despite its high porosity, could release very fine particles; which would create a cement layer of clogging when deposited at the interface. This layer is an obstacle for water infiltration, thus rendering the device thus constructed unsuitably for groundwater recharge, by reducing its life.

Rejuvenation of Water Bodies by Widening of Nallahas for Ground Water Recharge and Irrigation System at Very Low Cost-A Review of Literature

Rejuvenation of Water Bodies by Widening of Nallahas for Ground Water Recharge and Irrigation System at Very Low Cost-A Review of Literature

NDMA and NDMA precursor attenuation in environmental buffers prior to groundwater recharge for potable reuse

Natural attenuation of N-nitrosodimethylamine (NDMA) and NDMA precursors was evaluated in infiltration basins, a riverbed filtration system, and constructed wetlands operated as part of a managed aquifer recharge system. Initial NDMA concentrations up to 9.0 ng/L in infiltration basins (advanced purified, recycled water) before sunrise declined to non-detect (<1.5 ng/L) by 10:00 A.M due to natural photolysis (half-life of 33 to 86 min dependent on solar irradiance). NDMA fortified controls adjacent to the infiltration basin showed similar results, while concentrations in dark controls did not change over the basin's hydraulic retention time. NDMA precursor concentrations did not change significantly in the basin containing advanced-treated water from a potable reuse treatment plant, indicating that photolysis did not remove NDMA precursors nor did photolysis produce a significant amount of precursors. For the other environmental buffers evaluated, NDMA removal was variable through laboratory scale soil columns (22 cm height), in full-scale riverbed filtration system that pre-filters water prior to infiltration basin recharge, and in the constructed wetland. Variability in NDMA removal through the wetlands is attributed to high turbidity. In the case of the riverbed filtration system, variability is likely due to short exposure times to sunlight. For the soil columns, limited NDMA removal is attributed to inefficacy of soil aquifer treatment in removing NDMA over short travel times/distances. NDMA precursors were also ineffectively removed in these systems, with effluent concentrations occasionally exceeding influent concentrations. Overall, the removal of NDMA in environmental buffers utilized for planned or de facto indirect potable reuse is dependent on the system's capacity for photolysis, while NDMA precursors are more recalcitrant and unlikely to be removed in such systems without enhancement or sufficient hydraulic residence times.

Geophysical Characterization of Hydraulic Properties around a Managed Aquifer Recharge System over the Llobregat River Alluvial Aquifer (Barcelona Metropolitan Area)

Managed aquifer recharge using surface or regenerated water plays an important role in the Barcelona Metropolitan Area in increasing storage volume to help operators cope with the runoff variability and unexpected changes in surface water quality that are aggravated by climate change. The specific aim of the research was to develop a non-invasive methodology to improve the planning and design of surface-type artificial recharge infrastructures. To this end, we propose an approach combining direct and indirect exploration techniques such as electrical resistivity tomography (ERT), frequency domain electromagnetics and data from double-ring infiltration tests, trial pits, research boreholes and piezometers. The ERT method has provided much more complete and representative information in a zone where the recharge project works below design infiltration rates. The geometry of the hydrogeological units and the aquifer-aquiclude contact are accurately defined through the models derived from the interpretation of ERT cross-sections in the alluvial aquifer setting. Consequently, prior to the construction of recharge basins, it is highly recommended to conduct the proposed approach in order to identify the highest permeability areas, which are, therefore, the most suitable for aquifer artificial recharge.

Lithium Planar Deposition vs Whisker Growth: Crucial Role of Surface Diffusion.

Lithium plating-one of the critical processes in the desired high-energy lithium metal batteries-is accompanied by lithium whisker growth, which causes several problems that prevent the employment of metallic lithium anodes in rechargeable systems. They include low coulombic efficiency, electrolyte consumption, and the risk of short circuits, which can lead to thermal runaway of the battery. In recent years several strategies were suggested to mitigate whisker growth. The mechanism of this process, however, still lacks understanding. Here, we reveal the importance of surface diffusion along grain boundaries in solid lithium. We show that, at first, the plating of lithium onto a lithium substrate is possible as bulk crystal growth with a planar crystallization front for the Li grains with oblique (nonperpendicular to the surface) grain boundaries. Further, the developed compressive stress makes lithium diffusion to the grain base unfavorable, and new grains nucleate at the surface. The latter are the cause of the whisker growth from their roots. These findings indicate that the control of grain-boundary diffusion and grain size and structure paves the way to overcome the nonuniform morphology of plated lithium.

Energy, economic, and environmental impacts of sustainable biochar systems in rural China

Biochar production from biomass is a promising solution to tackle the energy and environmental challenges of rural China such as air pollution, soil contamination and degradation, sustainable agricultural waste management, and climate change. Small- and medium-scale (a few kW to 3 MW) gasification systems consisting of a gasification reactor and a gas engine had an energy efficiency of 15–20% and large-scale (>5 MW) systems via an integrated gasification combined cycle had an electrical efficiency of 26–30%. Low system efficiencies and high costs incurred by collection, transport, and pretreatment are some of the major barriers to the economic feasibility of biochar production systems in China. Mobile systems or distributed biochar production systems serve as promising solutions to reduce the biomass cost by utilizing locally generated waste biomass and catering for the bioenergy and biochar demands of local rural communities. From an energy application perspective, biochar production systems can generate heat and electricity, and biochar can serve as an energy storage material in supercapacitors and rechargeable batteries systems and can be used in anaerobic digestion to enhance overall energy recovery. Biochar can be used to achieve carbon sequestration and remediation of soil, and odor control in livestock farms. Systems converting locally generated biomass into energy and biochar that are used by local villages wait to be tested to clarify the intricacies of their viability and large-scale environmental and energy impacts in rural China.

Revisiting Classical Rocking Chair Lithium-Ion Battery

Rechargeable energy storage systems become an indispensable element to drive the electrified modern society as attributed to the groundbreaking development of rocking chair lithium-ion batteries (LIBs). For the past thirty years, LIBs significantly advance in their building materials and architectures that continue to shape forthcoming electronic applications with high energy density and ultra-long service periods. As facing the limitation of performance metrics by traditional LIBs, varied forms of rechargeable batteries emerged and the relevant researches are a fast-paced field, which call for the fundamental understanding of battery concepts. This review covers the basic study on the rocking chair LIBs regarding the charge storage mechanism across the principal battery components of the anode, cathode, and electrolytes, including the redox reactions and mass transports at the interfaces. Chronological perspectives on the active host materials are explored along with their advantages, scientific hurdles, and preliminary solutions from their outset to the recent designs. Finally, we discuss the most feasible and practical forms of batteries toward which the rocking chair LIBs should proceed.

Rated Power Determination for Autonomous Micro Combined Heat and Power and Rechargeable Battery System

Abstract An autonomous micro combined heat and power (Micro-CHP) is usually installed to increase energy efficiency and reduce energy costs in areas remote from large power systems. The main goal of autonomous Micro-CHP is to provide residential and industrial areas with electricity and heat. By designing an autonomous Micro-CHP, one of the key issues is the determination of rated power, since the energy efficiency of equipment and the costs of fossil fuels depend on the rated power. The mathematical model can better calculate the necessary rated power for an autonomous Micro-CHP in the case of operation with rechargeable batteries. Overall, the results have shown that the engine characteristics, operation process of three-phase synchronous generator and statistical information on loads are the criteria for improving energy efficiency.

Three-Year Follow-Up of a Prospective, Double Blinded Multi-Center RCT Evaluating DBS with a Multiple Source, Constant-Current Rechargeable System for Treatment of Parkinson's Disease (INTREPID)

Three-Year Follow-Up of a Prospective, Double Blinded Multi-Center RCT Evaluating DBS with a Multiple Source, Constant-Current Rechargeable System for Treatment of Parkinson's Disease (INTREPID)

Peering into Batteries: Electrochemical Insight Through In Situ and Operando Methods over Multiple Length Scales

Summary In order to overcome the limitations of static and destructive characterizations of Li-ion battery materials and components, comprehensive investigation peering into batteries over various length and time scales is essential. In this regard, emerging in situ and operando characterization methodologies focusing on multiple size domains become a powerful approach to resolve current challenges and navigate future directions. This perspective provides a series of illustrative examples of in situ and operando characterizations over atomic, crystallite/particle, electrode, and battery system length scales with a focus on two electrode material classes: insertion and conversion materials. The operating principles, features, analysis methods, and information gained from each characterization method are discussed. Herein, we present the necessity and opportunity for in situ and operando characterization of electrochemical energy storage materials and systems. Further, we suggest future directions to gain the insight needed to tackle currently intractable issues on Li-ion battery application, failure, and emerging design concepts.

Density functional theory study of ultra-thin InSe electrodes for Na and Mg ion storage and transport

One of the key challenges facing rechargeable battery systems is the low charge–discharge rate, due to the sluggish intercalation of cation into anode materials. Here we performed first principles calculations to investigate the adsorption and migration of Li, Na and Mg atoms on 2D layered InSe–a promising anode material. All metal atoms prefer to adsorb on the octahedral sites of InSe. The ion migration energy barriers significantly decline after a 40% interlayer expansion. On a monolayer InSe, Mg and Na species possess much lower activation barriers than Li, especially Mg, accompanied by a weakening of adsorption. Our study expands the range of anode materials for the Na and Mg-ion batteries.

Understanding Electrochemical Reaction Mechanisms and Properties of Rechargeable Aluminum-Sulfur and Aluminum-Selenium Batteries

The continual rise in global energy demands coupled with recent incremental advances in the cost and energy density of lithium-ion batteries have given researchers an impetus to investigate high-energy-density batteries such as those that use multivalent-ions. Rechargeable Al metal batteries have recently garnered significant interest due to its low cost, earth abundance, inherent safety, and high volumetric (8040 mAh cm -3) and gravimetric (2980 mAh g -1) capacities due to the trivalent nature of Al3+ ions (3-electron redox). Commercialization of rechargeable aluminum battery systems has been limited, however, due to the small number of (i) electrolytes that enable reversible electrodeposition of Al metal at room temperature and (ii) positive electrode materials that are compatible with the electrolytes while providing high capacity and cycle life. Sulfur (S) and selenium (Se) are promising positive electrode materials for rechargeable battery systems as they exhibit very high specific capacities during electrochemical conversion reactions.Sulfur is a very low-cost material due to its earth abundance and generation as a byproduct of the petroleum industry, while it can provide a very high specific capacity up to 1675 mAh g-1. Commercialization of battery systems with sulfur electrodes has been hindered due to its low electrical conductivity, high volume expansion during galvanostatic cycling, and deleterious polysulfide shuttle reactions during charge and discharge1-3. Selenium, like sulfur, is also a chalcogen and is expected to exhibit similar electrochemical reactions. Although Se is a heavier element and consequently exhibits lower specific capacity (675 mAh g-1), it possesses significantly higher electronic conductivity compared to sulfur4 that would be beneficial in mitigating key challenges that faces sulfur electrodes, such as low active material utilization and high charge transfer overpotentials during galvanostatic cycling. To date, there are few reports of Al-S2,3, and Al-Se4,5 systems. There is no clear consensus on the electrochemical reaction mechanism during the charge/discharge process, while capacity fade plagues both systems during galvanostatic cycling.Here, aluminum-sulfur (Al-S) and aluminum-selenium (Al-Se) cells were investigated with a chloroaluminate ionic liquid electrolyte, AlCl3:[EMIm][Cl] (molar ratio of 1.5:1), whose electrochemical reaction mechanisms and ensuing reaction products were analyzed via a combination of bulk (XRD, NMR) and surface (XPS) analyzation techniques. Electrochemical experiments for Al-S batteries showed high initial capacities close to 1200 mAh g-1, which exhibited a inverse correlation with galvanostatic cycling rate. For Al-S batteries a higher capacity was observed upon charge, compared to discharge, pointing towards either an unwanted side reaction or polysulfide-shuttle-like behavior. This behavior occurred predominately at low current densities and affected the reversibility of the system. For the Al-Se batteries, the two different reaction mechanisms that have been previously reported were found to be dependent on (i) the applied current density and (ii) the crystallinity of the active material, as shown by XRD. We demonstrate that, with appropriate cycling conditions, both reaction mechanisms can occur during a single charge/discharge step, thus significantly increasing the capacity and the electrochemical window of the Al-Se cell. A significant capacity fade was also observed over a course of multiple cycles showing similar behavior compared to Al-S cells.To understand the reaction mechanisms of Al-S and Al-Se batteries at a molecular level, solid-state and liquid-state 27Al NMR and 77Se NMR measurements (on Al-Se systems) were acquired on the electrodes and electrolyte at different states-of-charge, respectively. XPS was also performed on cycled chalcogen electrodes to understand surface compositions. The combination of electrochemical, spectroscopic, and X-ray diffraction data yield insights into the reaction mechanisms and products, including the aluminum coordination environments and relative populations in these environments. This work establishes the potential of conversion-type aluminum-chalcogen batteries as high-energy-density energy storage systems and highlights the importance that molecular-level analytical tools like NMR spectroscopy can have in clarifying electrochemical mechanisms in emerging electrochemical systems.Reference L. Ellis, K. T. Lee, and L. F. Nazar, Chemistry of Materials, 22, 691 (2010).Gao et al., Angew. Chemie - Int. Ed., 55, 9898–9901 (2016).. X. Yu, M. J. Boyer, G. S. Hwang, and A. Manthiram, Chem, 4, 586–598 (2018).Liu et al., Nano Energy, 66, 104159 (2019)Li, J. Liu, X. Huo, J. Li, and F. Kang, ACS Appl. Mater. Interfaces, 11, 45709–45716 (2019).

(Europe Section Alessandro Volta Medal Award) Electrolytes and Metallic Anodes: About an Old Argument That Marks the Fundamental Understanding of Modern Metal Anodes in Advanced Battery Systems

Simple, yet meaningful, experiments, already carried out in the 18th century by Galvani and Volta, are at the very base of modern batteries that shape our society. From the very first muscle twitch to batteries found nowadays in nearly every part of modern life, with the best known example of a modern battery represented by the lithium ion battery (LIB), the same basic principles are present. The comparably fast and seminal development of LIBs through assiduous collective efforts was granted the 2019 Nobel Prize in Chemistry.[1] Besides all modern perspectives, fundamental principles are still being derived from the early works of Volta and Galvani, which have not been always in agreement.Because the LIB technology is more and more approaching its ceiling in terms of specific energy (Wh kg−1) and energy density (Wh L−1) imposed by the nature of intercalation chemistry, metal-based anodes, such as Li, Na, Mg, Ca, Zn and Al, are currently considered for the next evolutional step of battery technology.[2,3,4] Independent of the chosen materials, the chemistry of the anodes (graphite, silicon or metal anodes) with the electrolyte plays a crucial role in the development of the batteries. In LIBs, the formation of a solid electrolyte interphase (SEI) on graphite in organic media induced by an external current/voltage and involving the reduction of the electrolyte components was key for the stable operation of such anodes.[5] Similar processes for metal-based anodes do not necessarily require electrode polarization conditions and can occur spontaneously. For example, supplementary to SEI formation on the Li surface, induced by the extremely low redox potential of metallic lithium (−3.04 V vs. SHE), other processes of Li deterioration, namely galvanic corrosion (worth also considering here: dendrite growth, volume changes of the Li anode, low Coulombic efficiency), have to be scrutinized. Recently, battery researchers revisited the corrosion phenomena in lithium metal batteries (LMBs).[6,7] A systematic study focused on the corrosion-related processes in model Li anodes (using Li powder) revealed the great significance that such processes exercise on the performance of LMBs.[7]From a different perspective, flammable non-aqueous electrolytes, widely used in the LIB/LMB systems, are causing increased safety concerns. As an alternative, Zn has been regarded as a potential anode material for aqueous batteries because of its high theoretical volumetric capacity and suitable redox potential (−0.76 V vs. SHE), along with an intrinsic safety from the aqueous electrolyte nature. Similar to the Li anode in nonaqueous electrolytes, the Zn anode has also long-standing challenges in conventional alkaline electrolytes, such as chemical instability (e.g. corrosion) and electrochemical irreversibility (e.g. non-uniform electrodeposition/-dissolution, dendrite growth).[8]In this perspective, the two worlds of Li-based and Zn-based battery systems are united and attributed to the lessons by Volta and Galvani. Metals from the Volta pile (Cu and Zn) and modern metals (Li) are discussed side by side and in correlation to each other. Solutions to address their challenges, and thus overcome the barriers of their application, in rechargeable systems will be highlighted. It is emphasized that the combination of metals (e.g. Li) with metal ions (e.g. Zn2+) can result in formation of intermetallic phases, able to improve stability of the electrodes under cell operation conditions. This can further result in an increase in safety and cycle life of the batteries utilizing metals as negative electrodes.[9] Special attention will be also given to the obstacles caused by the alkaline electrolytes with focus on the fundamental understanding of Zn reaction mechanisms. Approaches to overcome the challenges are presented and evaluated for their potential to facilitate further research and development of electrolytes in these systems.

(Invited) Bismuth Enables Formation of Disordered Birnessite in Rechargeable Alkaline Batteries

Recent advances in rechargeable Zn/MnO2 alkaline batteries have shown promise for scalable energy storage systems which provide a safe, low-cost alternative to current Li-ion technologies and have a demonstrated lifetime over thousands of cycles. This cathode technology is based on a 2-electron Mn redox process where a layered birnessite-type phase has been shown to form after the first cycle with excellent reversibility between the discharge product, Mn(OH)2 when Bi2O3 and Cu constituents were added to the electrode.1 For this system to reach costs < $100/kWh, the complete reduction to Mn2+ must be reversible with high mass loading (> 20 mAh/cm2). To get a complete understanding of the role of Bi2O3 in the reversible formation of a birnessite phase a multimodal structural characterization strategy is necessary to identify all the various intermediates formed during battery cycling. Spectroscopic evidence including Raman and X-ray absorption spectroscopy during cycling provide crucial insights into intermediate phases and variations in redox activity, with and without additives.Early demonstrations of Bi3+ containing constituents with MnO2 in alkaline batteries increased the cyclability of these systems up to hundreds of cycles with low mass loading.2,3 Later investigations followed up by hypothesizing the presence of Bi3+ could potentially catalyze the reduction of Mn3+ to Mn2+ and that upon subsequent charge promotes the formation of a layered, birnessite, MnO2 structure.4 The quick reduction of Mn3+/2+ is critical because the presence of Mn3+ is associated with the irreversible phase change to the Mn3O4 spinel structure.5,6 Figure 1 shows the birnessite vibrations at 510, 578 and 635 cm-1 form only at the top of charge with the Mn3O4 spinel vibration at 659 cm-1 present throughout the entire charging process. However, with the addition of the Bi2O3 a birnessite phase forms earlier in the charge process allowing for the facile conversion between the Mn(OH)2 and charged birnessite phase. This birnessite phase could not be identified through diffraction methods and is therefore considered a highly disordered phase that exists as a short-lived intermediate during battery operation. Using operando diffraction and X-ray near edge absorption spectroscopy (XANES) we characterize the disordered intermediate birnessite and the final crystalline phase formed as the final charge product. We expect the results will provide crucial insight into the development of aqueous, rechargeable battery systems utilizing MnO2. Figure 1 Operando Raman spectroscopy. (A) Individual Raman spectra, (B) contour map, and (C) corresponding voltage profile of the battery with a K-birnessite electrode. (D) Individual Raman spectra, (E) contour map, and (F) corresponding voltage profile of the battery with a K-birnessite with Bi2O3 electrode. Yadav, G. G.; Gallaway, J. W.; Turney, D. E.; Nyce, M.; Huang, J.; Wei, X.; Banerjee, S., Nature Communications 2017, 8, 14424.Dzieciuch, M. A.; Gupta, N.; Wroblowa, H. S., Journal of The Electrochemical Society 1988, 135 (10), 2415-2418.Wroblowa, H. S.; Gupta, N., Journal of Electroanalytical Chemistry and Interfacial Electrochemistry 1987, 238 (1), 93-102.Im, D.; Manthiram, A., Journal of The Electrochemical Society 2003, 150 (1), A68-A73.Gallaway, J. W.; Hertzberg, B. J.; Zhong, Z.; Croft, M.; Turney, D. E.; Yadav, G. G.; Steingart, D. A.; Erdonmez, C. K.; Banerjee, S., Power Sources 2016, 321, 135-142.Gallaway, J. W.; Yadav, G. G.; Turney, D. E.; Nyce, M.; Huang, J.; Chen-Wiegart, Y.-c. K.; Williams, G.; Thieme, J.; Okasinski, J. S.; Wei, X.; Banerjee, S., Journal of The Electrochemical Society 2018, 165 (13), A2935-A2947. Figure 1

Confined-Space-Induced Side Reactions in Li-O2 Electrochemistry

Rechargeable lithium-oxygen battery (LOB) is one of potentially promising candidates for next-generation batteries of which criteria typically set as > 500 Wh kg-1 in a full-cell configuration [1]. However this rechargeable battery system suffers from a wide spectrum of side reactions at the all main components, i.e. anode, electrolyte, and cathode, and also at their interfaces [2-5]. Therefore, the suppression of side reactions is a key challenge in LOB. Especially, understanding mechanism of side reactions occurring at the interface of porous cathode/electrolyte is important to improve the basic electrochemical properties of LOB, therefore, is also essential to enhance the battery performances of LOB. In our previous works, we prepared a variety of porous-carbon-based cathodes to investigate the effects of heteroatom doping or hierarchical porestructures in Li-O2 electrochemistry [6-9], and found that a porestructure gives considerably strong influences to electrochemical growth/decomposition of Li2O2 at a solid-liquid interface in porous electrodes. Driven by these previous findings, in this work, we aimed to understand further details of the Li-O2 electrode process in porous solids by, and show here that unfavorable side reactions in porous electrodes are induced if the reaction takes place at confined-spaces.In our study, we controlled the electrochemical growth of Li2O2 in a porous electrode by changing current densities, and therefore can selectively form Li2O2 at macropores or mesopores/macropores confirmed by nitrogen adsorption/desorption experiments and X-ray diffractometry. Furthermore, operando gas analysis, combining electrochemical experiments and on-line mass spectrometry, revealed that the Li2O2 formed in macropores can almost solely proceed the electrochemical decomposition reaction for O2 generation, on the other hand, Li2O2 in mesopores generate a considerable amount of CO2, even around 3.5 V vs Li/Li+. These results indicated that a confinement space could trigger Li2O2 to unfavorable side reactions to form CO2. Therefore, a fine control of porestructure in cathodes is important for LOB not only to improve round trip energy efficient but also to obtain reversible Li2O2 formation, i.e. O2 + 2Li+ + 2e − ↔ Li2O2 [10].In the presentation, a detailed mechanism will be explained how confined-space-induced side reactions are proceeded.[1] M. Ue, K. Sakaushi, K. Uosaki, Materials Horizons, DOI: 10.1039/D0MH00067A (2020).[2] B. D. McCloskey, D. S. Bethune, R. M. Shelby, G. Girishkumar, A. C. Luntz, J. Phys. Chem. Lett., 2, 1161 (2011).[3] B. D. McCloskey, A. Speidel, R. Scheffler, D. C. Miller, V. Viswanathan, J. S. Hummelshøj, J. K. Nørskov, A. C. Luntz, J. Phys. Chem. Lett., 3, 997 (2012).[4] W.-J. Kwak, Rosy, D. Sharon, C. Xia, H. Kim, L. R. Johnson, P. G. Bruce, L. F. Nazar, Y.-K. Sun, A. A. Frimer, M. Noked, S. A. Freunberger, D. Aurbach. Chem. Rev., DOI: 10.1021/acs.chemrev.9b00609 (2020).[5] T. Liu, J. P. Vivek, E. W. Zhao, J. Lei, N. Garcia-Araez, C. P. Grey, Chem. Rev., DOI: 10.1021/acs.chemrev.9b00545 (2020).[6] K. Sakaushi, T.-P. Fellinger, M. Antonietti, ChemSusChem, 8, 1156 (2015).[7] K. Sakaushi, S.-J. Yang, T.-P. Fellinger, M. Antonietti, J. Mater. Chem. A, 3, 11720 (2015).[8] K. Sakaushi, M. Antonietti, Bull. Chem. Soc. Jpn., 88, 386 (2015).[9] K. Sakaushi, M. Antonietti, Acc. Chem. Res., 48, 1591 (2015).[10] K. Sakaushi, H. Asahina, K. Uosaki, in preparation.

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.

Interlayer Space Engineering of MXenes for Electrochemical Energy Storage Applications.

The increasing demand for high-performance rechargeable energy storage systems has stimulated the exploration of advanced electrode materials. MXenes are a class of two-dimensional (2D) inorganic transition metal carbides/nitrides, which are promising candidates in electrodes. The layered structure facilitates ion insertion/extraction, which offers promising electrochemical characteristics for electrochemical energy storage. However, the low capacity accompanied by sluggish electrochemical kinetics of electrodes as well as interlayer restacking and collapse significantly impede their practical applications. Recently, interlayer space engineering of MXenes by different chemical strategies have been widely investigated in designing functional materials for various applications. In this review, an overview of the most recent progress of 2D MXenes engineering by intercalation, surface modification as well as heterostructures design is provided. Moreover, some critical challenges in future research on MXene-based electrodes have been also proposed.