Lithium–sulfur (Li–S) batteries with high energy density and long cycle life are considered to be one of the most promising next‐generation energy‐storage systems beyond routine lithium‐ion ...batteries. Various approaches have been proposed to break down technical barriers in Li–S battery systems. The use of nanostructured metal oxides and sulfides for high sulfur utilization and long life span of Li–S batteries is reviewed here. The relationships between the intrinsic properties of metal oxide/sulfide hosts and electrochemical performances of Li–S batteries are discussed. Nanostructured metal oxides/sulfides hosts used in solid sulfur cathodes, separators/interlayers, lithium‐metal‐anode protection, and lithium polysulfides batteries are discussed respectively. Prospects for the future developments of Li–S batteries with nanostructured metal oxides/sulfides are also discussed.
Nanostructured metal oxides and sulfides are considered as polysulfide anchoring sites in working Li–S batteries for the battery's high sulfur utilization and long life span. The relationships between the intrinsic properties of the metal oxide/sulfide hosts and the electrochemical performances of Li–S batteries are reviewed.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Owing to high specific energy, low cost, and environmental friendliness, lithium–sulfur (Li–S) batteries hold great promise to meet the increasing demand for advanced energy storage beyond portable ...electronics, and to mitigate environmental problems. However, the application of Li–S batteries is challenged by several obstacles, including their short life and low sulfur utilization, which become more serious when sulfur loading is increased to the practically accepted level above 3–5 mg cm−2. More and more efforts have been made recently to overcome the barriers toward commercially viable Li–S batteries with a high sulfur loading. This review highlights the recent progress in high‐sulfur‐loading Li–S batteries enabled by hierarchical design principles at multiscale. Particularly, basic insights into the interfacial reactions, strategies for mesoscale assembly, unique architectures, and configurational innovation in the cathode, anode, and separator are under specific concerns. Hierarchy in the multiscale design is proposed to guide the future development of high‐sulfur‐loading Li–S batteries.
High‐sulfur‐loading lithium–sulfur (Li–S) batteries enabled by multiscale hierarchical design principles are reviewed. The basic insights into the interfacial reactions, strategies for mesoscale assembly, unique architectures, and configurational innovation in the cathode, anode, and separator are of specific concern. Hierarchy in the multiscale design is proposed to guide the future development of high‐sulfur‐loading Li–S batteries.
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Lithium–sulfur (Li–S) batteries are considered as promising next‐generation energy storage devices due to their ultrahigh theoretical energy density, where soluble lithium polysulfides are crucial in ...the Li–S electrochemistry as intrinsic redox mediators. However, the poor mediation capability of the intrinsic polysulfide mediators leads to sluggish redox kinetics, further rendering limited rate performances, low discharge capacity, and rapid capacity decay. Here, an organodiselenide, diphenyl diselenide (DPDSe), is proposed to accelerate the sulfur redox kinetics as a redox comediator. DPDSe spontaneously reacts with lithium polysulfides to generate lithium phenylseleno polysulfides (LiPhSePSs) with improved redox mediation capability. The as‐generated LiPhSePSs afford faster sulfur redox kinetics and increase the deposition dimension of lithium sulfide. Consequently, the DPDSe comediator endows Li–S batteries with superb rate performance of 817 mAh g−1 at 2 C and remarkable cycling stability with limited anode excess. Moreover, Li–S pouch cells with the DPDSe comediator achieve an actual initial energy density of 301 Wh kg−1 and 30 stable cycles. This work demonstrates a novel redox comediation strategy with an effective organodiselenide comediator to facilitate the sulfur redox kinetics under pouch cell conditions and inspires further exploration in mediating Li–S kinetics for practical high‐energy‐density batteries.
An organodiselenide, diphenyl diselenide (DPDSe), is proposed to accelerate the sulfur redox kinetics as a redox comediator, which endows Li–S batteries with superb rate performance, remarkable cycling stability, and high actual energy density of 301 Wh kg−1. This work demonstrates a novel redox comediation strategy to facilitate the sulfur redox kinetics under practical pouch cell conditions.
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Lithium–sulfur (Li–S) batteries deliver a high theoretical energy density of 2600 Wh kg−1, and hold great promise to serve as a next‐generation high‐energy‐density battery system. Great progress has ...been achieved in cathode design to deal with the intrinsic problems of sulfur cathodes, including low conductivity, the dissolution of polysulfide intermediate, and volume fluctuation. However, aiming at the practical applications of Li–S batteries, the weight percentage of sulfur in cathode materials and the overall areal sulfur loading need to be significantly increased, which inevitably complicate the process and cause heavy shuttle effect, slow redox kinetics, and more undesirable reaction pathways. Recently, rationally designing efficient mediators, as well as incorporating them into a working battery, emerges to be a promising method to construct high‐energy‐density Li–S batteries. The influence of mediators on Li–S batteries appears to be the enhancement in redox kinetics and the increase in reaction efficiency. In this feature article, the mechanistic understanding of redox kinetics in Li–S reactions is discussed, and then a comprehensive analysis of the recent advances in both heterogeneous and homogeneous mediator design is provided. A mediator perspective in building high‐energy‐density Li–S batteries is also included.
Mediators in lithium–sulfur batteries can enhance the redox kinetics and increase the reaction efficiency, which benefit the practical applications requiring a high sulfur content and a high areal loading amount. This feature article discusses the mechanism of redox kinetics, and reviews the recent advances in heterogeneous/homogeneous mediator design in lithium–sulfur batteries.
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The performance of Li‐ion batteries (LIBs) is highly dependent on their interfacial chemistry, which is regulated by electrolytes. Conventional electrolyte typically contains polar solvents to ...dissociate Li salts. Herein we report a weakly solvating electrolyte (WSE) that consists of a pure non‐polar solvent, which leads to a peculiar solvation structure where ion pairs and aggregates prevail under a low salt concentration of 1.0 M. Importantly, WSE forms unique anion‐derived interphases on graphite electrodes that exhibit fast‐charging and long‐term cycling characteristics. First‐principles calculations unravel a general principle that the competitive coordination between anions and solvents to Li ions is the origin of different interfacial chemistries. By bridging the gap between solution thermodynamics and interfacial chemistry in batteries, this work opens a brand‐new way towards precise electrolyte engineering for energy storage devices with desired properties.
A weakly solvating electrolyte affords a new path towards anion‐derived interfacial chemistry in lithium‐ion batteries. By formulating electrolyte with a non‐polar solvent, ion pairs and aggregates prevail under normal concentrations and give rise to anion‐derived interphases on graphite electrodes with superior electrochemical performances.
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Solid‐state lithium (Li) metal batteries (SSLMBs) have become a research hotspot in the energy storage field due to the much‐enhanced safety and high energy density. However, the SSLMBs suffer from ...failures including dendrite‐induced short circuits and contact‐loss‐induced high impedance, which are highly related to the Li plating/stripping kinetics and hinder the practical application of SSLMBs. The maximum endurable current density of lithium battery cycling without cell failure in SSLMB is generally defined as critical current density (CCD). Therefore, CCD is an important parameter for the application of SSLMBs, which can help to determine the rate‐determining steps of Li kinetics in solid‐state batteries. Herein, the theoretical and practical meanings for CCD from the fundamental thermodynamic and kinetic principles, failure mechanisms, CCD identifications, and influence factors for improving CCD performances are systematically reviewed. Based on these fundamental understandings, a series of strategies and outlooks for future researches on SSLMB are presented, endeavoring on increasing CCD for practical SSLMBs.
The critical current density (CCD) is an important standard for future solid‐state Li metal batteries (SSLMBs), which is highly related to power density and fast charge capability. The CCD can help to unravel the rate determining factors of Li kinetics including special mass transport and charge transfer at solid–solid interfaces.
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Flexible energy storage systems are imperative for emerging flexible devices that are revolutionizing our life. Lithium-ion batteries, the current main power sources, are gradually approaching their ...theoretical limitation in terms of energy density. Therefore, alternative battery chemistries are urgently required for next-generation flexible power sources with high energy densities, low cost, and inherent safety. Flexible lithium-sulfur (Li-S) batteries and analogous flexible alkali metal-chalcogen batteries are of paramount interest owing to their high energy densities endowed by multielectron chemistry. In this review, we summarized the recent progress of flexible Li-S and analogous batteries. A brief introduction to flexible energy storage systems and general Li-S batteries has been provided first. Progress in flexible materials for flexible Li-S batteries are reviewed subsequently, with a detailed classification of flexible sulfur cathodes as those based on carbonaceous (
e.g.
, carbon nanotubes, graphene, and carbonized polymers) and composite (polymers and inorganics) materials and an overview of flexible lithium anodes and flexible solid-state electrolytes. Advancements in other flexible alkali metal-chalcogen batteries are then introduced. In the next part, we emphasize the importance of cell packaging and flexibility evaluation, and two special flexible battery prototypes of foldable and cable-type Li-S batteries are highlighted. In the end, existing challenges and future development of flexible Li-S and analogous alkali metal-chalcogen batteries are summarized and prospected.
This review summarizes recent progress in flexible Li-S and analogous alkali metal-chalcogen batteries, including flexible chalcogen cathodes, flexible alkali metal anodes, flexible solid-state electrolytes, and flexible battery prototypes.
Safe and rechargeable lithium metal batteries have been difficult to achieve because of the formation of lithium dendrites. Herein an emerging electrolyte based on a simple solvation strategy is ...proposed for highly stable lithium metal anodes in both coin and pouch cells. Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO3) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions, and forming a uniform solid electrolyte interphase (SEI), with an abundance of LiF and LiNxOy on a working lithium metal anode with dendrite‐free lithium deposition. Ultrahigh Coulombic efficiency (99.96 %) and long lifespans (1000 cycles) were achieved when the FEC/LiNO3 electrolyte was applied in working batteries. The solvation chemistry of electrolyte was further explored by molecular dynamics simulations and first‐principles calculations. This work provides insight into understanding the critical role of the solvation of lithium ions in forming the SEI and delivering an effective route to optimize electrolytes for safe lithium metal batteries.
Not dead ′Li′: Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO3) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions and forming a uniform solid electrolyte interphase (SEI). An abundance of LiF and LiNxOy is formed on the working lithium metal anode and contributes to dendrite‐free lithium deposition.
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The lithium metal anode is regarded as a promising candidate in next‐generation energy storage devices. Lithium nitrate (LiNO3) is widely applied as an effective additive in ether electrolyte to ...increase the interfacial stability in batteries containing lithium metal anodes. However, because of its poor solubility LiNO3 is rarely utilized in the high‐voltage window provided by carbonate electrolyte. Dissolution of LiNO3 in carbonate electrolyte is realized through an effective solvation regulation strategy. LiNO3 can be directly dissolved in an ethylene carbonate/diethyl carbonate electrolyte mixture by adding trace amounts of copper fluoride as a dissolution promoter. LiNO3 protects the Li metal anode in a working high‐voltage Li metal battery. When a LiNi0.80Co0.15Al0.05O2 cathode is paired with a Li metal anode, an extraordinary capacity retention of 53 % is achieved after 300 cycles (13 % after 200 cycles for LiNO3‐free electrolyte) and a very high average Coulombic efficiency above 99.5 % is achieved at 0.5 C. The solvation chemistry of LiNO3‐containing carbonate electrolyte may sustain high‐voltage Li metal anodes operating in corrosive carbonate electrolytes.
Liquid assets: LiNO3 can be dissolved directly in an ethylene carbonate/diethyl carbonate electrolyte mixture by adding a trace amount of copper fluoride to promote dissolution. The solvation structure of the electrolyte system protects the lithium metal anode in a working high‐voltage lithium metal battery. NCA=LiNi0.80Co0.15Al0.05O2.
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The electrode/electrolyte interface plays a critical role in stabilizing the cycling performance and prolonging the service life of rechargeable batteries to meet the sustainable energy requirements ...of the mobile society. The understanding of interfaces is still at the preliminary stage due to the limited research techniques and variable properties with time and potential. Herein, the latest developments focused on the interfaces in rechargeable systems including the cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) are reviewed. The possible formation mechanisms of the electrode/electrolyte interface are discussed, followed by the introduction of two key influencing factors, specific adsorption and solvated coordinate structure, which will dominate the formation of the interface. Finally, the structure and chemical composition of the interface as well as the possible transport mechanism of lithium ions in the interface and the strategies to regulate the pathway through the interface are presented in detail. This work sheds light on the fundamental understanding of the interface and provides rational scientific principles in designing the electrode/electrolyte interface and inspires the rational design of long‐term cycling rechargeable batteries.
The electrode/electrolyte interface plays a critical role in stabilizing the cycling performance and prolonging the service life of rechargeable batteries. This work discusses the formation mechanism of the interface and summarizes the progress in the structure/composition modulation of the interface toward advanced battery systems.
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