Correlating Polysulfide Solvation Structure with Electrode Kinetics towards Long-Cycling Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are promising due to ultrahigh theoretical energy density. However, their cycling lifespan is crucially affected by the electrode kinetics of lithium polysulfides. Herein, the polysulfide solvation structure is correlated with polysulfide electrode kinetics towards long-cycling Li-S batteries. The solvation structure derived from strong solvating power electrolyte induces fast anode kinetics and rapid anode failure, while that derived from weak solvating power electrolyte causes sluggish cathode kinetics and rapid capacity loss. By contrast, the solvation structure derived from medium solvating power electrolyte balances cathode and anode kinetics and improves the cycling performance of Li-S batteries. Li-S coin cells with ultra-thin Li anodes and high-S-loading cathodes deliver 146 cycles and a 338 Wh kg-1 pouch cell undergoes stable 30 cycles. This work clarifies the relationship between polysulfide solvation structure and electrode kinetics and inspires rational electrolyte design for long-cycling Li-S batteries.

Reforming the Uniformity of Solid Electrolyte Interphase by Nanoscale Structure Regulation for Stable Lithium Metal Batteries.

The stability of high-energy-density lithium metal batteries depends on the uniformity of solid electrolyte interphase (SEI) on lithium metal anodes. Rationally improving SEI uniformity is hindered by poorly understanding the effect of structure and components of SEI on its uniformity. Herein, a bilayer structure of SEI formed by isosorbide dinitrate (ISDN) additives in localized high-concentration electrolytes was demonstrated to improve SEI uniformity. In the bilayer SEI, LiNx Oy generated by ISDN occupies top layer and LiF dominates bottom layer next to anode. The uniformity of lithium deposition is remarkably improved with the bilayer SEI, mitigating the consumption rate of active lithium and electrolytes. The cycle life of lithium metal batteries with bilayer SEI is three times as that with common anion-derived SEI under practical conditions. A prototype lithium metal pouch cell of 430 Wh kg-1 undergoes 173 cycles. This work demonstrates the effect of a reasonable structure of SEI on reforming SEI uniformity.

Carbon allowance allocation based on comprehensive performance of carbon emissions: Case of typical industries in Zhengzhou.

Studying the comprehensive performance of industrial carbon emission has profound significance for improving carbon allowance allocation scheme and achieving the carbon neutrality target. The paper selects 181 enterprises in Zhengzhou as the case, a comprehensive carbon emission performance indicator system and a carbon allowance allocation model were established, and compared with other allocation schemes (historical/baseline method). The results showed that the overall differences in the comprehensive performance evaluation indicator of carbon emissions in typical industries in Zhengzhou were obvious, and there was a correlation with the characteristics of industrial production activities. The overall emission reduction of Zhengzhou was 244.33×103t, and the emission reduction ratio was 7.94% by simulating carbon allowance allocation under the comprehensive performance. The carbon allowance allocation method based on the comprehensive performance has the strongest restraint on the "high emission, low performance" industry, which is more equitable and more conducive to carbon emission reduction. In the future, it will be recommended to give full play to the leading role of the government, implement industrial carbon allowance allocation based on the comprehensive performance evaluation of carbon emissions, to achieve multi-objectives of resource conservation, environmental pollution abatement, and carbon reduction.

Electrolyte Design for Improving Mechanical Stability of Solid Electrolyte Interphase in Lithium-Sulfur Batteries.

Practical lithium-sulfur (Li-S) batteries are severely plagued by the instability of solid electrolyte interphase (SEI) formed in routine ether electrolytes. Herein, an electrolyte with 1,3,5-trioxane (TO) and 1,2-dimethoxyethane (DME) as co-solvents is proposed to construct a high-mechanical-stability SEI by enriching organic components in Li-S batteries. The high-mechanical-stability SEI works compatibly in Li-S batteries. TO with high polymerization capability can preferentially decompose and form organic-rich SEI, strengthening mechanical stability of SEI, which mitigates crack and regeneration of SEI and reduces the consumption rate of active Li, Li polysulfides, and electrolytes. Meanwhile, DME ensures high specific capacity of S cathodes. Accordingly, the lifespan of Li-S batteries increases from 75 cycles in routine ether electrolyte to 216 cycles in TO-based electrolyte. Furthermore, a 417 Wh kg-1 Li-S pouch cell undergoes 20 cycles. This work provides an emerging electrolyte design for practical Li-S batteries.

An Organodiselenide Comediator to Facilitate Sulfur Redox Kinetics in Lithium-Sulfur Batteries with Encapsulating Lithium Polysulfide Electrolyte.

Lithium-sulfur (Li-S) batteries are regarded as promising high-energy-density energy storage devices. However, the cycling stability of Li-S batteries is restricted by the parasitic reactions between Li metal anodes and soluble lithium polysulfides (LiPSs). Encapsulating LiPS electrolyte (EPSE) can efficiently suppress the parasitic reactions but inevitably sacrifices the cathode sulfur redox kinetics. To address the above dilemma, a redox comediation strategy for EPSE is proposed to realize high-energy-density and long-cycling Li-S batteries. Concretely, dimethyl diselenide (DMDSe) is employed as an efficient redox comediator to facilitate the sulfur redox kinetics in Li-S batteries with EPSE. DMDSe enhances the liquid-liquid and liquid-solid conversion kinetics of LiPS in EPSE while maintains the ability to alleviate the anode parasitic reactions from LiPSs. Consequently, a Li-S pouch cell with a high energy density of 359 Wh kg-1 at cell level and stable 37 cycles is realized. This work provides an effective redox comediation strategy for EPSE to simultaneously achieve high energy density and long cycling stability in Li-S batteries and inspires rational integration of multi-strategies for practical working batteries.

Weakening the Solvating Power of Solvents to Encapsulate Lithium Polysulfides Enables Long-Cycling Lithium-Sulfur Batteries.

Long cycling lifespan is a prerequisite for practical lithium-sulfur batteries yet is restricted by side reactions between soluble polysulfides and the lithium-metal anode. The regulation on solvation structure of polysulfides renders encapsulating polysulfides electrolytes (EPSE) as a promising solution to suppress the parasitic reactions. The solvating power of the solvents in the outer solvent shell of lithium polysulfides is critical for the encapsulation effect of EPSE. Herein, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE) is demonstrated as a superior outer-shell solvent to construct EPSE. Based on the large steric hindrance of the fluorohydrocarbon chains, the electron-withdrawing perfluoro segment (CF2  further endows HFE with prominently weak solvating power. The HFE-EPSE improves the lifespan from 54 to 135 cycles for lithium-sulfur batteries with an ultrathin lithium-metal anode (50 µm) and high-areal-loading sulfur cathode (4.4 mg cm-2 ). Furthermore, a 334 Wh kg-1 lithium-sulfur pouch cell (2.4 Ah level) with HFE-EPSE stably undergoes 25 cycles. This work demonstrates the role of weakening solvating power of outer-shell solvents to construct superior EPSE and inspires the significance of the solvation chemistry of polysulfides to achieve practical lithium-sulfur batteries.

Assessing the ecological risk induced by PM2.5 pollution in a fast developing urban agglomeration of southeastern China.

High PM2.5 concentration threats ecosystem functions but limited quantitative studies have recognized PM2.5 pollution as an individual stressor in evaluating ecological risk. In this study, we applied a machine-learning-based simulation model incorporating full-coverage satellite-driven PM2.5 dataset to estimate high-resolution ground PM2.5 concentration for the Golden Triangle of Southern Fujian Province, China (GTSF) in 2030 under two Representative Concentration Pathways (RCPs). Based on the simulation output, the ecological risk's spatiotemporal change and the risk for different land cover types, which were caused by PM2.5 pollution, were assessed. We found that the PM2.5 levels and ecological risk in the GTSF under RCP 4.5 would be reduced while those under RCP 8.5 would continue to increase. The regions with the highest ecological risk under RCP 4.5 are the most urbanized and industrialized districts, while those with the highest ecological risk under RCP 8.5 are of the highest rate in urbanization and the greatest decrease in planetary potential layer height. For both base years and 2030 under two RCPs, the ecological risk on developed land is the highest, while that on the forest is the lowest. Our study can provide useful information for environmental policy risk assessment.

Inhibiting intercrystalline reactions of anode with electrolytes for long-cycling lithium batteries.

The life span of lithium batteries as energy storage devices is plagued by irreversible interfacial reactions between reactive anodes and electrolytes. Occurring on polycrystal surface, the reaction process is inevitably affected by the surface microstructure of anodes, of which the understanding is imperative but rarely touched. Here, the effect of grain boundary of lithium metal anodes on the reactions was investigated. The reactions preferentially occur at the grain boundary, resulting in intercrystalline reactions. An aluminum (Al)-based heteroatom-concentrated grain boundary (Al-HCGB), where Al atoms concentrate at grain boundary, was designed to inhibit the intercrystalline reactions. In particular, the scalable preparation of Al-HCGB was demonstrated, with which the cycling performance of a pouch cell (355 Wh kg-1) was significantly improved. This work opens a new avenue to explore the effect of the surface microstructure of anodes on the interfacial reaction process and provides an effective strategy to inhibit reactions between anodes and electrolytes for long-life-span practical lithium batteries.

Fluorinating the Solid Electrolyte Interphase by Rational Molecular Design for Practical Lithium-Metal Batteries.

The lifespan of practical lithium (Li)-metal batteries is severely hindered by the instability of Li-metal anodes. Fluorinated solid electrolyte interphase (SEI) emerges as a promising strategy to improve the stability of Li-metal anodes. The rational design of fluorinated molecules is pivotal to construct fluorinated SEI. Herein, design principles of fluorinated molecules are proposed. Fluoroalkyl (-CF2 CF2 -) is selected as an enriched F reservoir and the defluorination of the C-F bond is driven by leaving groups on ß-sites. An activated fluoroalkyl molecule (AFA), 2,2,3,3-tetrafluorobutane-1,4-diol dinitrate is unprecedentedly proposed to render fast and complete defluorination and generate uniform fluorinated SEI on Li-metal anodes. In Li-sulfur (Li-S) batteries under practical conditions, the fluorinated SEI constructed by AFA undergoes 183 cycles, which is three times the SEI formed by LiNO3 . Furthermore, a Li-S pouch cell of 360 Wh kg-1 delivers 25 cycles with AFA. This work demonstrates rational molecular design principles of fluorinated molecules to construct fluorinated SEI for practical Li-metal batteries.

Toward Practical High-Energy-Density Lithium-Sulfur Pouch Cells: A Review.

Lithium-sulfur (Li-S) batteries promise great potential as high-energy-density energy-storage devices due to their ultrahigh theoretical energy density of 2600 Wh kg-1 . Evaluation and analysis on practical Li-S pouch cells are essential for achieving actual high energy density under working conditions and affording developing directions for practical applications. This review aims to afford a comprehensive overview of high-energy-density Li-S pouch cells regarding 7 years of development and to point out further research directions. Key design parameters to achieve actual high energy density are addressed first, to define the research boundaries distinguished from coin-cell-level evaluation. Systematic analysis of the published literature and cutting-edge performances is then conducted to demonstrate the achieved progress and the gap toward practical applications. Following that, failure analysis as well as promotion strategies at the pouch cell level are, respectively, discussed to reveal the unique working and failure mechanism that shall be accordingly addressed. Finally, perspectives toward high-performance Li-S pouch cells are presented regarding the challenges and opportunities of this field.

Modification of Nitrate Ion Enables Stable Solid Electrolyte Interphase in Lithium Metal Batteries.

The lifespan of high-energy-density lithium metal batteries (LMBs) is hindered by heterogeneous solid electrolyte interphase (SEI). The rational design of electrolytes is strongly considered to obtain uniform SEI in working batteries. Herein, a modification of nitrate ion (NO3 - ) is proposed and validated to improve the homogeneity of the SEI in practical LMBs. NO3 - is connected to an ether-based moiety to form isosorbide dinitrate (ISDN) to break the resonance structure of NO3 - and improve the reducibility. The decomposition of non-resonant -NO3 in ISDN enriches SEI with abundant LiNx Oy and induces uniform lithium deposition. Lithium-sulfur batteries with ISDN additives deliver a capacity retention of 83.7 % for 100 cycles compared with rapid decay with LiNO3 after 55 cycles. Moreover, lithium-sulfur pouch cells with ISDN additives provide a specific energy of 319 Wh kg-1 and undergo 20 cycles. This work provides a realistic reference in designing additives to modify the SEI for stabilizing LMBs.

Protocol for quantitative nuclear magnetic resonance for deciphering electrolyte decomposition reactions in anode-free batteries.

In this protocol, we describe the quantification of electrolytes using nuclear magnetic resonance. We detail the steps involved for battery cycling, sample preparation, instrument operation, and data analysis. The protocol can be used to quantify electrolyte decomposition reactions and the apparent electron transfer numbers of different electrolyte components. The protocol is optimized for lithium-based anode-free batteries but can also be applied to other rechargeable batteries. For complete details on the use and execution of this protocol, please refer to Zhou et al. (2022).1.

Anode Material Options Toward 500 Wh kg-1 Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) battery is identified as one of the most promising next-generation energy storage systems due to its ultra-high theoretical energy density up to 2600 Wh kg-1 . However, Li metal anode suffers from dramatic volume change during cycling, continuous corrosion by polysulfide electrolyte, and dendrite formation, rendering limited cycling lifespan. Considering Li metal anode as a double-edged sword that contributes to ultrahigh energy density as well as limited cycling lifespan, it is necessary to evaluate Li-based alloy as anode materials to substitute Li metal for high-performance Li-S batteries. In this contribution, the authors systematically evaluate the potential and feasibility of using Li metal or Li-based alloys to construct Li-S batteries with an actual energy density of 500 Wh kg-1 . A quantitative analysis method is proposed by evaluating the required amount of electrolyte for a targeted energy density. Based on a three-level (ideal material level, practical electrode level, and pouch cell level) analysis, highly lithiated lithium-magnesium (Li-Mg) alloy is capable to achieve 500 Wh kg-1 Li-S batteries besides Li metal. Accordingly, research on Li-Mg and other Li-based alloys are reviewed to inspire a promising pathway to realize high-energy-density and long-cycling Li-S batteries.

A Successive Conversion-Deintercalation Delithiation Mechanism for Practical Composite Lithium Anodes.

Lithium (Li) metal anodes are attractive for high-energy-density batteries. Dead Li is inevitably generated during the delithiation of deposited Li based on a conversion reaction, which severely depletes active Li and electrolyte and induces a short lifespan. In this contribution, a successive conversion-deintercalation (CTD) delithiation mechanism is proposed by manipulating the overpotential of the anode to restrain the generation of dead Li. The delithiation at initial cycles is solely carried out by a conversion reaction of Li metal. When the overpotential of the anode increases over the delithiation potential of lithiated graphite after cycling, a deintercalation reaction is consequently triggered to complete a whole CTD delithiation process, largely reducing the formation of dead Li due to a highly reversible deintercalation reaction. Under practical conditions, the working batteries based on a CTD delithiation mechanism maintain 210 cycles with a capacity retention of 80% in comparison to 110 cycles of a bare Li anode. Moreover, a 1 Ah pouch cell with a CTD delithiation mechanism operates for 150 cycles. The work ingeniously restrains the generation of dead Li by manipulating the delithiation mechanisms of the anode and contributes to a fresh concept for the design of practical composite Li anodes.

Antibacterial activity of chrysophsin-3 against oral pathogens and Streptococcus mutans biofilms.

Dental caries and pulpal diseases are common oral bacterial infectious diseases, the prevention and treatment of these diseases require the control of the causative pathogens, such as Streptococcus mutans (S. mutans) and Enterococcus faecalis. As a cationic antimicrobial peptide, Chrysophsin-3 has broad-spectrum bactericidal activity against both Gram-positive and Gram-negative bacteria which may cause a variety of oral infectious diseases. The present study evaluated the potential of chrysophsin-3 against several oral pathogens and S.mutans biofilms. The cytotoxic activity of chrysophsin-3 against human gingival fibroblasts (HGFs) was investigated for potential oral application. We use minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and time-kill assay to evaluate the killing effect of chrysophsin-3. Then scanning electron microscopy (SEM) and Transmission Electron Microscope (TEM) were used to analyze the change of morphology and membrane of the pathogens, Live/Dead staining and confocal scanning laser microscopy (CSLM) was used to observe S. mutans biofilms. The results indicate that chrysophsin-3 has varying antimicrobial activities against different oral bacteria. Chrysophsin-3 did not cause obvious cytotoxicity in HGFs at concentrations of 32-128 µg/ml for 5 min or 8 µg/ml for 60 min. SEM revealed membranous blebs and pore formation on the bacterial cell surface, and TEM showed loss of the nucleoid and dissolution of the cytoplasmic space. Furthermore, the CSLM images indicate that chrysophsin-3 can reduce the viability of the cells within the biofilms significantly and had a comparatively lethal effect against S. mutans biofilms. Taken together, our finding suggests that chrysophsin-3 has potential clinical application in oral infectious disease, especially in preventing and treating dental caries.

The carrier transition from Li atoms to Li vacancies in solid-state lithium alloy anodes.

The stable cycling of energy-dense solid-state batteries is highly relied on the kinetically stable solid-state Li alloying reactions. The Li metal precipitation at solid-solid interfaces is the primary cause of interface fluctuations and battery failures, whose formation requires a clear mechanism interpretation, especially on the key kinetic short board. Here, we introduce the lithium alloy anode as a model system to quantify the Li kinetic evolution and transition from the alloying reaction to the metal deposition in solid-state batteries, identifying that there is a carrier transition from Li atoms to Li vacancies during lithiation processes. The rate-determining step is charge transfer or Li atom diffusion at different lithiation stages.

Stable Anion-Derived Solid Electrolyte Interphase in Lithium Metal Batteries.

High-energy-density lithium (Li) metal batteries are severely hindered by the dendritic Li deposition dictated by non-uniform solid electrolyte interphase (SEI). Despite its unique advantages in improving the uniformity of Li deposition, the current anion-derived SEI is unsatisfactory under practical conditions. Herein regulating the electrolyte structure of anions by anion receptors was proposed to construct stable anion-derived SEI. Tris(pentafluorophenyl)borane (TPFPB) anion acceptors with electron-deficient boron atoms interact with bis(fluorosulfonyl)imide anions (FSI- ) and decrease the reduction stability of FSI- . Furthermore, the type of aggregate cluster of FSI- in electrolyte changes, FSI- interacting with more Li ions in the presence of TPFPB. Therefore, the decomposition of FSI- to form Li2 S is promoted, improving the stability of anion-derived SEI. In working Li | LiNi0.5 Co0.2 Mn0.3 O2 batteries under practical conditions, the anion-derived SEI with TPFPB undergoes 194 cycles compared with 98 cycles of routine anion-derived SEI. This work inspires a fresh ground to construct stable anion-derived SEI by manipulating the electrolyte structure of anions.

Reclaiming Inactive Lithium with a Triiodide/Iodide Redox Couple for Practical Lithium Metal Batteries.

High-energy-density lithium (Li) metal batteries suffer from a short lifespan owing to apparently ceaseless inactive Li accumulation, which is accompanied by the consumption of electrolyte and active Li reservoir, seriously deteriorating the cyclability of batteries. Herein, a triiodide/iodide (I3 - /I- ) redox couple initiated by stannic iodide (SnI4 ) is demonstrated to reclaim inactive Li. The reduction of I3 - converts inactive Li into soluble LiI, which then diffuses to the cathode side. The oxidation of LiI by the delithiated cathode transforms cathode into the lithiation state and regenerates I3 - , reclaiming Li ion from inactive Li. The regenerated I3 - engages the further redox reactions. Furthermore, the formation of Sn mitigates the corrosion of I3 - on active Li reservoir sacrificially. In working Li | LiNi0.5 Co0.2 Mn0.3 O2 batteries, the accumulated inactive Li is significantly reclaimed by the reversible I3 - /I- redox couple, improving the lifespan of batteries by twice. This work initiates a creative solution to reclaim inactive Li for prolonging the lifespan of practical Li metal batteries.

Electrolyte Structure of Lithium Polysulfides with Anti-Reductive Solvent Shells for Practical Lithium-Sulfur Batteries.

The lithium-sulfur (Li-S) battery is regarded as a promising secondary battery. However, constant parasitic reactions between the Li anode and soluble polysulfide (PS) intermediates significantly deteriorate the working Li anode. The rational design to inhibit the parasitic reactions is plagued by the inability to understand and regulate the electrolyte structure of PSs. Herein, the electrolyte structure of PSs with anti-reductive solvent shells was unveiled by molecular dynamics simulations and nuclear magnetic resonance. The reduction resistance of the solvent shell is proven to be a key reason for the decreased reactivity of PSs towards Li. With isopropyl ether (DIPE) as a cosolvent, DIPE molecules tend to distribute in the outer solvent shell due to poor solvating power. Furthermore, DIPE is more stable than conventional ether solvents against Li metal. The reactivity of PSs is suppressed by encapsulating PSs into anti-reductive solvent shells. Consequently, the cycling performance of working Li-S batteries was significantly improved and a pouch cell of 300 Wh kg-1 was demonstrated. The fundamental understanding in this work provides an unprecedented ground to understand the electrolyte structure of PSs and the rational electrolyte design in Li-S batteries.

Shielding Polysulfide Intermediates by an Organosulfur-Containing Solid Electrolyte Interphase on the Lithium Anode in Lithium-Sulfur Batteries.

The lithium-sulfur (Li-S) battery is regarded as a promising high-energy-density battery system, in which the dissolution-precipitation redox reactions of the S cathode are critical. However, soluble Li polysulfides (LiPSs), as the indispensable intermediates, easily diffuse to the Li anode and react with the Li metal severely, thus depleting the active materials and inducing the rapid failure of the battery, especially under practical conditions. Herein, an organosulfur-containing solid electrolyte interphase (SEI) is tailored for the stabilizaiton of the Li anode in Li-S batteries by employing 3,5-bis(trifluoromethyl)thiophenol as an electrolyte additive. The organosulfur-containing SEI protects the Li anode from the detrimental reactions with LiPSs and decreases its corrosion. Under practical conditions with a high-loading S cathode (4.5 mgS cm-2 ), a low electrolyte/S ratio (5.0 µL mgS -1 ), and an ultrathin Li anode (50 µm), a Li-S battery delivers 82 cycles with an organosulfur-containing SEI in comparison to 42 cycles with a routine SEI. This work provokes the vital insights into the role of the organic components of SEI in the protection of the Li anode in practical Li-S batteries.