Lean Electrolyte Conditions Research Articles

Developing High Energy Density Li-S Batteries via Pore-Structure Regulation of Porous Carbon Based Electrocatalyst.

The mesopores and macropores within porous carbon materials help increasethe surface for the depostion of solid-state products, reducethe Li2S film thickness, enhanceelectron and mass transport, and accelerate the reaction kinetics. However, an excessive amount of mesopores and macropores can lead to increased electrolyte consumption, particularly at high sulfur loadings, where excessive electrolyte usage hampers the enhancement of practical energy density in lithium-sulfur (Li-S) batteries. A rational pore structure can minimize the amount of electrolyte to fill the pores, thereby reducing electrolyte consumption while achieving rapid reaction kinetics and a high gravimetric energy density. In this work, the pore structure of carbon nanosheet-based electrocatalysts is precisely controlled by adjusting the content of a water-soluble potassium chloride template, allowing for in-depth investigation of the relationship between pore structure, electrolyte usage, and electrochemical performance in Li-S batteries. The molybdenum carbide-embedded carbon nanosheet (MoC-CNS) electrocatalyst, with an optimized pore structure, facilitates exceptional electrochemical performance under high sulfur loading and lean electrolyte conditions. Ultimately, the MoC-CNS-3-based Li-S battery achieved stable operation over 50 cycles under high sulfur loading (12mgcm-2) and a low electrolyte-to-sulfur (E/S) ratio of 4uLmg-1, delivering a high gravimetric energy density of 354.5Whkg-1. This work provides a viable strategy for developing high-performance Li-S batteries.

Trace Metal Impurities Induce Differences in Lithium-Sulfur Batteries.

Carbon nanotubes (CNTs) with exceptional conductivity have been widely adopted in lithium-sulfur (Li-S) batteries. While trace metal impurities in CNTs have demonstrated electrocatalytic activity in various catalytic processes, their influence on sulfur electrocatalysis in Li-S batteries has been largely overlooked. Herein, we reveal that the trace metal impurities content in CNTs significantly improves the specific capacity and cycling performance of Li-S batteries by analyzing both our own results and previous literature with CNTs as the sulfur hosts. Even under lean electrolyte conditions (E/S ratio of 5 μL mgs-1), we demonstrate that a small content of metal impurities in CNTs (∼2 wt %) could account for a 14.3% increase in specific capacity and a 14.1% increase in capacity retention under a high sulfur loading of 3.5 mg cm-2. The electron transfer from confined metal catalysts within CNTs leads to electron accumulation at the carbon interface, facilitating electron donation to adsorbed sulfur species and lowering the energy barrier for Li2S formation.

Anionic Doping in Layered Transition Metal Chalcogenides for Robust Lithium-Sulfur Batteries.

Lithium-sulfur batteries (LSBs) are among the most promising next-generation energy storage technologies. However, a slow Li-S reaction kinetics at the LSB cathode limit their energy and power densities. To address these challenges, this study introduces an anionic-doped transition metal chalcogenide as an effective catalyst to accelerate the Li-S reaction. Specifically, a tellurium-doped, carbon-supported bismuth selenide with Se vacancies (Te-Bi2Se3-x@C) is prepared and tested as a sulfur host in LSB cathodes. X-ray absorption and in-situ X-ray diffraction analyses reveal that Te doping induces lattice distortions and modulates the local coordination environment and electronic structure of Bi atoms to promote the catalytic activity toward the conversion of polysulfides. Additionally, the generated Se vacancies alter the electronic structure around atomic defect sites, increase the carrier concentration, and activate unpaired cations to effectively trap polysulfides. As a result, LSBs based on Te-Bi2Se3-x@C/S cathodes demonstrate outstanding specific capacities of 1508 mAh·g-1 at 0.1C, excellent rate performance with 655 mAh·g-1 at 5C, and near-integral cycle stability over 1000 cycles. Furthermore, under high sulfur loading of 6.4 mg·cm-2, a cathode capacity exceeding 8 mAh·cm-2 is sustained at 0.1C current rate, with 6.4 mAh·cm-2 retained after 300 cycles under lean electrolyte conditions (6.8 μL·mg-1).

Anionic Doping in Layered Transition Metal Chalcogenides for Robust Lithium‐Sulfur Batteries

Lithium‐sulfur batteries (LSBs) are among the most promising next‐generation energy storage technologies. However, a slow Li‐S reaction kinetics at the LSB cathode limit their energy and power densities. To address these challenges, this study introduces an anionic‐doped transition metal chalcogenide as an effective catalyst to accelerate the Li‐S reaction. Specifically, a tellurium‐doped, carbon‐supported bismuth selenide with Se vacancies (Te‐Bi2Se3‐x@C) is prepared and tested as a sulfur host in LSB cathodes. X‐ray absorption and in‐situ X‐ray diffraction analyses reveal that Te doping induces lattice distortions and modulates the local coordination environment and electronic structure of Bi atoms to promote the catalytic activity toward the conversion of polysulfides. Additionally, the generated Se vacancies alter the electronic structure around atomic defect sites, increase the carrier concentration, and activate unpaired cations to effectively trap polysulfides. As a result, LSBs based on Te‐Bi2Se3‐x@C/S cathodes demonstrate outstanding specific capacities of 1508 mAh·g‐1 at 0.1C, excellent rate performance with 655 mAh·g‐1 at 5C, and near‐integral cycle stability over 1000 cycles. Furthermore, under high sulfur loading of 6.4 mg·cm‐2, a cathode capacity exceeding 8 mAh·cm‐2 is sustained at 0.1C current rate, with 6.4 mAh·cm‐2 retained after 300 cycles under lean electrolyte conditions (6.8 μL·mg‐1).

Understanding the Dynamics of Sulfur Droplets Formation in Lean-Electrolyte and Low-Temperature Lithium-Sulfur Batteries.

Lithium-sulfur batteries (LSBs) afford great promises as the next-generation rechargeable batteries due to the high energy density and low cost of sulfur cathodes. Lean-electrolyte condition constitutes the prerequisite for high-energy LSBs, but the insulating sulfur particles hinder capacity utilization, especially at low temperatures. Here, the electrochemical generation of liquid sulfur droplets in the LSB system are studied and elucidate the polysulfide oxidation reaction (SOR) kinetics under different electrolyte/sulfur (E/S) ratios and low-temperature conditions. The real-time observations under in situ optical and Raman microscopies indicate that the formation of liquid sulfur during SOR is independent of the E/S ratio and can be preserved over a wide range of operating temperatures. Quantification of the polysulfide reactant concentrations and the amounts of the liquid sulfur product under different charging conditions reveal pseudo-zero-order kinetics and E/S ratio-dependent reaction constants for the SOR process. In addition, under extreme conditions of -20°C and E/S ratio of 5µLmg-1, liquid sulfur can still be preserved by following the rapid SOR kinetics. These findings provide new insights into the liquid sulfur generation dynamics in Li─S chemistry, which enables a deeper understanding of the effects of the E/S ratio and working temperature on the oxidation kinetics in LSBs.

Favorable Moderate Adsorption of Polysulfide on FeNi3 Intermetallic Compound Accelerating Conversion Kinetics for Advanced Lithium-Sulfur Batteries.

Sluggish conversion kinetics of polysulfides during discharge and the severe shuttle effect significantly hinder the practical application of lithium-sulfur (Li-S) batteries. In this work, the lattice engineering strategy of Fe hybridization is employed to manipulate the bulk phase spacing of FeNi3 (space group Pm3m) intermetallic compounds to adjust the 3d electronic structure, optimizing the adsorption of polysulfides, thereby accelerating the catalytic conversion. As a result, FeNi2.25@OC achieves favorable moderate adsorption toward polysulfides. Due to the larger number of electrons occupying the lowest occupied molecular orbital of Li2S4, the S-S bonds are weakened and broken. Temperature-dependent experiments confirm that FeNi2.25@OC exhibits the lowest activation energy and can effectively accelerate the catalytic conversion of polysulfides. The Li-S cell assembled with FeNi2.25@OC modified PP separator delivers a high initial discharge specific capacity of 1219.5 mAh g-1 at 0.2 C. Even at a high sulfur loading of 6.06mg cm-2 and lean electrolyte conditions (6 µL mg-1), it can cycle stably for 60 cycles.

Highly Solvating Electrolytes with Core-Shell Solvation Structure for Lean-Electrolyte Lithium-Sulfur Batteries.

The practical energy density of lithium-sulfur batteries is limited by the low sulfur utilization at lean electrolyte conditions. The highly solvating electrolytes (HSEs) promise to address the issue at harsh conditions, but the conflicting challenges of long-term stability of radical-mediated sulfur redox reactions (SRR) and the poor stability with lithium metal anode (LMA) have dimmed the efforts. We now present a unique core-shell solvation structured HSE formulated with classical ether-based solvents and phosphoramide co-solvent. The unique core-shell solvation structure features confinement of the phosphoramide in the first solvation shell, which prohibits severe contact reactions with LMA and endows prolonged stability for [S3]⋅- radical, favoring a rapid radical-mediated solution-based SRR. The cell with the proposed electrolyte showing a high capacity of 864 mAh gsulfur -1 under high sulfur loading of 5.5 mgsulfur cm-2 and low E/S ratio of 4 μL mgsulfur -1. The strategy further enables steady cycling of a 2.71-A h pouch cell with a high specific energy of 307 W h kg-1. Our work highlights the fundamental chemical concept of tuning the solvation structure to simultaneously tame the SRR and LMA stability for metal-sulfur batteries wherein the electrode reactions are heavily coupled with electrolyte chemistry.

Linear Ether-Based Molten Li Salt Solvate Electrolytes for Li-Metal Batteries

Li metal batteries have attracted much attention as the next-generation rechargeable batteries owing to the exceptionally high theoretical capacity (3860 mAh g⁻¹) and the lowest electrode potential of Li metal electrode. Molten Li salt solvate electrolytes or highly concentrated electrolytes (HCEs) are an emerging class of electrolytes having a similarity to ionic liquids (ILs) in high ionic nature, and indeed some of which are found to behave like an IL.1 This type of the electrolytes have attracted considerable attention as prospective candidates for electrolyte materials in future Li metal batteries owing to their favorable properties both in the bulk and at the electrochemical interface. In this study, linear ether-based molten Li salt solvates were investigated for potential effects of weakly coordinating linear ethers on transport properties and battery performance. We focused on the electrolytes using lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) or lithium bis(fluorosulfonyl)amide (LiFSA) as the salt and linear chain monoethers such as methylpropyl ether (MPE), n-butylmethyl ether (BME), and ethyl propyl ether (EPE) as the solvent for lithium-sulfur and lithium metal batteries. Owing to the low lithium polysulfide solubility, low viscosity, relatively high ionic conductivity, high Li ion transference number, high reductive stability, and low specific gravity, all of which are favorable for achieving high-energy density batteries, linear ether-based molten Li salt solvates were found to be effective electrolytes. The correlation between Li ion solvation and ionic transport properties of the linear ethers with different alkyl chain length were further studied to optimize the electrolyte compositions. The chemical structure of the ethers had a strong impact on the Li ion coordination structure and ionic conductivity: the monomethyl ether such as MPE and BME showed more-pronounced Li ion coordination and higher ionic conductivity whereas steric hinderance of longer alkyl chains in ethers with longer alkyl chain length such as ethyl propyl ether (EPE) resulted in lower solvation number, enhanced ion pairing and lower ionic conductivity. The improved Li ion transport property of the linear ether-based electrolytes led to the better rate performance. Furthermore, a pouch-type cell demonstrated an energy density exceeding 300 Wh kg-1 under lean electrolyte conditions.2 Shigenobu, T. Sudoh, J. Murai, K. Dokko, M. Watanabe, K. Ueno, Chem. Rec., 2023, 23, e202200301.Ishikawa, S. Haga, K. Shigenobu, T. Sudoh, S. Tsuzuki, W. Shinoda, K. Dokko, M. Watanabe, K. Ueno, Faraday Discuss., 2024, Accepted Manuscript. DOI: 10.1039/D4FD00024B

Optimizing High Energy Density Sulfur Cathodes: A Multivariate Approach to Electrode Formulation and Processing

Lithium-sulfur (Li-S) batteries involve complex solid-liquid-solid phase transformations during both discharging and charging processes, where cathode materials, formulation, and structure play a crucial role. Here, a design of experiments (DoE) methodology and an empirical model are developed to systematically explore the interactions and trade-offs among cathode factors and process variables, and to obtain generalizable effects estimates for the multivariate system. Compared to the conventional one-factor-at-a-time (OFAT) approach, this work demonstrates advantages in both efficiency and accuracy by allowing the data to guide future research and decisions. An optimized cathode formulation and processing is predicted and validated experimentally, achieving over 1000 mAh g-1 in discharge capacity and improved cycling under practical lean electrolyte (4 µL mg-1 S) and high S-loading cathodes (>4 mg cm-2) conditions. The optimized cathode was scaled up and assembled into Li-S pouch cells, achieving 316 Wh kg-1 in cell level energy, proving that the comprehensive and rigorous framework for optimizing complex systems with DoE leads to improved performance in a practical pouch cell system.

Constructing valid Li+ fast-transfer channels on novel P(TPC@Lys-Li) separator to enable security, high energy density, and controllable Li dendrites for lithium-metal batteries

Lithium metal batteries (LMBs) attract widespread attention under current high energy density developments. However, wild Li dendrite propagations owing to chaotic Li depositions raise challenges for LMB blossoming. Separators with specific demands thus should be involved when smoothly transferring into LMBs. In this research, a fascinating P(TPC@Lys-Li) separator is prepared by the turbulent interfacial polymerization and electrospinning to ingeniously clarify dependencies of Li+ transfer dynamics on double electric layer thickness (DELT) regulations within porous skeletons. P(TPC@Lys-Li) enables negatively charged porous skeleton surface and compresses DELT, which constructs high-efficiency Li+ fast-transfer channels on porous skeletons and accelerates Li+ transfer speed by 18.3 times. Especially, P(TPC@Lys-Li) supplies extra Li+ for stable formations of solid electrolyte interphase (SEI) layer, homogenizing nucleation and growth behaviors during Li depositions. Remarkable C-rate capacity and cycle stability thus arise for assembled LMBs, holding 87.2 % capacity retention after 700 cycles at 0.5C even under high cathode loading and lean electrolyte conditions. P(TPC@Lys-Li) also maintains constant physical scale and unabated mechanical strength even at elevated temperatures approaching 200 °C, which provides excellent battery security as LMBs encounter uncontrollable thermal runaway. Above attractive features enable P(TPC@Lys-Li) separator to be potentially applied in LMBs demanding sufficient security, high-capacity density, and fast charge technology.

Highly Solvating Electrolytes with Core‐Shell Solvation Structure for Lean‐Electrolyte Lithium‐Sulfur Batteries

The practical energy density of lithium‐sulfur batteries is limited by the low sulfur utilization at lean electrolyte conditions. The highly solvating electrolytes (HSEs) promise to address the issue at harsh conditions, but the conflicting challenges of long‐term stability of radical‐mediated sulfur redox reactions (SRR) and the poor stability with lithium metal anode (LMA) have dimmed the efforts. We now present a unique core‐shell solvation structured HSE formulated with classical ether‐based solvents and phosphoramide co‐solvent. The unique core‐shell solvation structure features confinement of the phosphoramide in the first solvation shell, which prohibits severe contact reactions with LMA and endows prolonged stability for [S3]•– radical, favoring a rapid radical‐mediated solution‐based SRR. The cell with the proposed electrolyte showing a high capacity of 864 mA h gsulfur−1 under high sulfur loading of 5.5 mgsulfur cm−2 and low E/S ratio of 4 µL mgsulfur−1. The strategy further enables steady cycling of a 2.71‐A h pouch cell with a high specific energy of 307 W h kg−1. Our work highlights the fundamental chemical concept of tuning the solvation structure to simultaneously tame the SRR and LMA stability for metal‐sulfur batteries wherein the electrode reactions are heavily coupled with electrolyte chemistry.

Functional Separator with Poly(Acrylic Acid)-Enabled Li2CO3-Free Garnet Coating for Long-Cycling Lithium Metal Batteries.

Lithium metal batteries (LMBs) possess a theoretical energy density far surpassing that of commercial lithium-ion batteries (LIBs), positioning them as one of the most promising next-generation energy storage systems. Modifying separators with composite coatings comprising oxide solid-state electrolyte (SSE) particles and polymers can improve the cycling stability and safety of LMBs. However, exposure to air forms Li2CO3 on oxide SSE particles, diminishing their ion flux regulation at the electrode/electrolyte interface. Utilizing the reaction of Li2CO3 with polyacrylic acid (PAA) to form lithium polyacrylate (LiPAA), an ultra-thin composite coating on polyethylene (PE) separator with Li2CO3-free Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles and LiPAA binder is fabricated in one step. The exposed Li2CO3-free LLZTO surface increases the ionic conductivity and lithium ion (Li+) transference number of the functional separator, resulting in small resistance and uniform Li deposition of the Li metal anode. Consequently, the Li//LiCoO2 cell with the functional separator exhibits a significantly improved life of 980 cycles with 80.9% capacity retention under lean-electrolyte conditions. Both the Li//LiCoO2 coin cell and pouch cell using thin Li foil anode demonstrate good cycling stability and high mechanical robustness. This study provides a green and scalable approach for fabricating advanced separators for LMBs.

Heterostructure Mo2C/α-MoO3/G catalyst based heterogeneous catalysis/deposition mechanism for high-performance Li-S battery

Lithium-sulfur batteries (LSBs) have been recognized as a promising energy device due to their outstanding theoretical energy density and abundant resources. However, the commercial application remains obstruction by the sluggish redox kinetics and serious shuttle effect of polysulfides. Herein, a heterostructural Mo2C/α-MoO3/graphene (Mo2C/α-MoO3/G) catalyst based on a heterogeneous catalysis/deposition mechanism is proposed to address these issues. The prepared Mo2C/α-MoO3/G catalyst is feature with high-activity facet, fast electron delocalization and build-in electric field, which drastically promotes the redox kinetics of polysulfides on the surface of crystal phase. Simultaneously, the heterostructural Mo2C/α-MoO3/G catalyst is capable of capturing polysulfides effectively and eliciting the heterogeneous deposition of Li2S on the surface of amorphous phase, of which guarantee the efficient catalytic characteristic during the charge/discharge processes. In addition, the shuttle effect is restricted with a lower shuttle factor (∼0.02). Therefore, the assembled LSBs based Mo2C/α-MoO3/G catalyst modifying separator exhibits an impressive specific capacity of 1311.4 mAh g−1 at 0.2 C and excellent rate capability of 580.3 mAh g−1 at 4 C. More importantly, it demonstrated satisfied cycling stability even at a high sulfur loading mass (4.2 mgS cm−2) and lean electrolyte conditions (9.3 μL gS-1). This work reveals a novel paradigm for optimizing the kinetics behaviors to achieve the commercialization of LSBs.

P‐doped RuSe2 on Porous N‐Doped Carbon Matrix as Catalysts for Accelerated Sulfur Redox Reactions

AbstractMonocomponent catalysts exhibit the limited catalytic conversion of polysulfides due to their intrinsic electronic structure, but their catalytic activity can be improved by introducing heteroatoms to regulate its electronic structure. However, the rational selection principles of doping elements remain unclear. Here, we are guided by theoretical calculations to select the suitable doping elements based on the balanced relationship between the adsorption strength of lithium polysulfides (LiPSs) and catalytic activity of lithium sulfide. We apply the screening method to develop a new catalyst of phosphorus doped RuSe2, manifesting the further enhanced conductivity compared with original RuSe2, facilitating charge transfer and further modulating the d‐band center of RuSe2, thereby augmenting its effectiveness in interacting with LiPSs. Consequently, the assembled cell exhibits an areal capacity of 7.7 mAh cm−2, even under high sulfur loading of 8.0 mg cm−2 and a lean electrolyte condition (5.0 μL mg−1). This rational screening strategy offers a robust solution for the design of advanced catalysts in the field of lithium‐sulfur batteries and potentially other domains as well.

Machine learning-based design of electrocatalytic materials towards high-energy lithium||sulfur batteries development

The practical development of Li | |S batteries is hindered by the slow kinetics of polysulfides conversion reactions during cycling. To circumvent this limitation, researchers suggested the use of transition metal-based electrocatalytic materials in the sulfur-based positive electrode. However, the atomic-level interactions among multiple electrocatalytic sites are not fully understood. Here, to improve the understanding of electrocatalytic sites, we propose a multi-view machine-learned framework to evaluate electrocatalyst features using limited datasets and intrinsic factors, such as corrected d orbital properties. Via physicochemical characterizations and theoretical calculations, we demonstrate that orbital coupling among sites induces shifts in band centers and alterations in the spin state, thus influencing interactions with polysulfides and resulting in diverse Li-S bond breaking and lithium migration barriers. Using a carbon-coated Fe/Co electrocatalyst (synthesized using recycled Li-ion battery electrodes as raw materials) at the positive electrode of a Li | |S pouch cell with high sulfur loading and lean electrolyte conditions, we report an initial specific energy of 436 Wh kg−1 (whole mass of the cell) at 67 mA and 25 °C.

Optimizing high energy density sulfur cathodes: A multivariate approach to electrode formulation and processing

Lithium-sulfur (Li-S) batteries involve complex solid-liquid-solid phase transformations during both discharging and charging processes, where cathode materials, formulation, and structure play a crucial role. Here, a design of experiments (DoE) methodology and an empirical model are developed to systematically explore the interactions and trade-offs among cathode factors and process variables, and to obtain generalizable effects estimates for the multivariate system. Compared to the conventional one-factor-at-a-time (OFAT) approach, this work demonstrates advantages in both efficiency and accuracy by allowing the data to guide future research and decisions. An optimized cathode formulation and processing parameters are predicted and validated experimentally, achieving over 1000 mAh g−1 in discharge capacity and improved cycling under practical lean electrolyte (4 µL mg−1 S) and high S-loading cathodes (>4 mg cm−2) conditions. The optimized cathode was scaled up and assembled into Li-S pouch cells, achieving 316 Wh kg−1 in cell-level energy, proving that the comprehensive and rigorous framework for optimizing complex systems with DoE leads to improved performance in a practical pouch cell system.

P-doped RuSe2 on Porous N-Doped Carbon Matrix as Catalysts for Accelerated Sulfur Redox Reactions.

Monocomponent catalysts exhibit the limited catalytic conversion of polysulfides due to their intrinsic electronic structure, but their catalytic activity can be improved by introducing heteroatoms to regulate its electronic structure. However, the rational selection principles of doping elements remain unclear. Here, we are guided by theoretical calculations to select the suitable doping elements based on the balanced relationship between the adsorption strength of lithium polysulfides (LiPSs) and catalytic activity of lithium sulfide. We apply the screening method to develop a new catalyst of phosphorus doped RuSe2, manifesting the further enhanced conductivity compared with original RuSe2, facilitating charge transfer and further modulating the d-band center of RuSe2, thereby augmenting its effectiveness in interacting with LiPSs. Consequently, the assembled cell exhibits an areal capacity of 7.7 mAh cm-2, even under high sulfur loading of 8.0 mg cm-2 and a lean electrolyte condition (5.0 μL mg-1). This rational screening strategy offers a robust solution for the design of advanced catalysts in the field of lithium-sulfur batteries and potentially other domains as well.

Quasi-solid-state sulfur cathode with ultralean electrolyte via in situ polymerization

Lean electrolytes (< 5 μL mgsulfur−1) play a critical role in the realization of Li-S battery devices with high energy density for practical applications. However, lean-electrolyte Li-S batteries suffer from rapid cycling deterioration caused by the worsened shuttle effect under low electrolyte/sulfur ratio (E/S). Herein, via in situ polymerization, we realize a quasi-solid-state polymer Li-S battery with lean electrolytes. In this system, the polymer electrolyte with flexible polymer chains can block the diffusion of polysulfides and protect the Li-metal anode from being corroded by polysulfides. Furthermore, in the in situ polymerization route, the liquid precursor can wet the porous cathode, the separator and the Li anode abundantly, so that the consequent solidification not only promises a highly integrated structure of the whole cell, but also freezes the electrolyte in the best distribution condition for the electrochemical reaction, especially under lean electrolyte condition. Notably, the quasi-solid-state Li-S battery can discharge normally with ultralean electrolyte of even 1 μL mgsulfur−1. Moreover, the pouch cell with low E/S (3 μL mg−1) delivers a high energy density of 369.8 Wh kg−1. This work demonstrates the feasibility of quasi-solid-state Li-S batteries under lean-electrolyte condition, accelerating the application of high-energy-density Li-S batteries in the future.

DMSO/DMF co-solvent precipitated nano-sulfur cathode for highly loading lithium-sulfur pouch cells

We employ a simple anti-solvent precipitation method to prepare sulfur nanoparticles. Dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) are chosen as co-solvents, and cetyltrimethylammonium bromide (CTAB) is used as a stabilizer. By adjusting parameters such as the ratio of solvents and concentration, we precisely control the supersaturation, finely tuning the size of the sulfur particles. To enhance the electrical conductivity of the electrode materials, we uniformly composite sulfur with reduced graphene oxide (rGO). As the sulfur particle size decreases, the charge transfer resistance of the S@rGO cathode rapidly decreases, demonstrating excellent electrode kinetics. A lithium-sulfur coin cell assembled with S@rGO-75 exhibits a discharge specific capacity of 1272 mAh g−1. After 180 cycles, the capacity retention remains at 89.1 %, with a Coulombic efficiency of 98.9 %. Additionally, a pouch cell (PC-75) achieves stable charge–discharge behavior at a total sulfur loading of 300 mg, with an initial discharge specific capacity of 1047 mAh g−1 and a capacity retention of 63.7 % after 80 cycles. Under lean electrolyte conditions (E/S = 1.5 μl mg−1), PC-75 maintains outstanding energy density (392.3 Wh kg−1). Based on PC-75, a drone achieves an ultra-long flight time of 255 s, providing preliminary evidence of the practical application potential of PC-75.

High-Density, Low-Tortuosity Sulfur Electrodes for High Energy Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries have attracted significant attention due to their promising theoretical energy and cost-effectiveness.[1] While recently studies have predominantly focused on increasing sulfur mass loading and utilization rate for high specific energy, there remains a noticeable gap in addressing the intrinsic challenge of improving volumetric energy density.[2] This challenge arises as many Li-S investigations rely on highly porous electrodes.[3] Here, we employ a shear-rolling approach to prepare free-standing electrodes characterized by high density (porosity<15%), low tortuosity, and substantial S content (>70%). The incorporation of a vascular-like porous network, facilitated by a pore soft template, plays a pivotal role in achieving high sulfur utilization (>1000 mAh g-1) in high-loading electrodes (>4 mg cm-2) under lean electrolyte condition (E/S 4 mL g-1). This approach results in an extraordinarily high volumetric energy density (668 Wh L-1 of dry cell) when applied to practical Li–S pouch cells. Our study underscores that realizing high volumetric energy in Li–S cell can be achieved by rationalizing the dense electrode architecture. Furthermore, the shear-rolling approach holds broad applicability for fabricating high-energy electrodes using porous or nanoparticle materials with desirable structures. Details of the progress will be discussed at the conference.