Origin and Acceleration of Insoluble Li2S2−Li2S Reduction Catalysis in Ferromagnetic Atoms-based Lithium-Sulfur Battery Cathodes

Accelerating insoluble Li₂S₂−Li₂S reduction catalysis to mitigate the shuttle effect has emerged as an innovative paradigm for high-efficient lithium-sulfur battery cathodes, such as single-atom catalysts by offering high-density active sites to realize in situ reaction with solid Li₂S₂. However, the profound origin of diverse single-atom species on solid-solid sulfur reduction catalysis and modulation principles remains ambiguous. Here we disclose the fundamental origin of Li₂S₂−Li₂S reduction catalysis in ferromagnetic elements-based single-atom materials to be from their spin density and magnetic moments. The experimental and theoretical studies disclose that the Fe−N₄-based cathodes exhibit the fastest deposition kinetics of Li₂S (226 mAh g⁻¹) and the lowest thermodynamic energy barriers (0.56 eV). We believe that the accelerated Li₂S₂−Li₂S reduction catalysis enabled via spin polarization of ferromagnetic atoms provides practical opportunities towards long-life batteries.     

Chloro-propylene Sulfite as Electrolyte Additive for Li/S Batteries

Chloro-propylene sulfite (ClPS) was employed as electrolyte additive of Li/S batteries for the first time. Linear potential sweep test showed that the C1PS keeps high electrochemical stability even under the voltage of 5.0V. Being used as electrolyte additive in Li/S batteries, C1PS displayed an excellent property for self-discharge prohibition. With C1PS additive the Li/S cells' initial discharge capacity was 856.2 mAh·g-1 and 830.8 mAh·g-1 at the current density of 15 mA·g-1 and 30 mA·g-1, after 30 cycles the discharge capacities were contained at as high as 753.8 mAh·g-1 and 715.6 mAh·g-1. By means of infrared spectra, TG/DTA experiment and element content analysis the speculated reason of CIPS's novel function as additive was proposed.     

Edge-functionalized acetylene black anchoring sulfur for high-performance Li–S batteries

To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanostructured sulfur cathodes are not so promising, because of the low volumetric energy density and high cost. In this work, we obtained the low-cost, scalable, eco-friendly mass production of edge-functionalized acetylene black-sulfur(FAB-S) composites by high-energy ball-milling technique for lithium sulfur batteries. The as-prepared FAB-S composite can deliver a high initial discharge capacity of 1304 mAh/g and still remain a reversible capacity of 814 mAh/g after 200 cycles at a charge-discharge rate of 0.2 C in the voltage range of 1.7–2.7 V. The observed excellent electrochemical properties demonstrate that the cathodes obtained by the facile high-energy ball-milling method as the cathode for rechargeable Li-S batteries are of great potential because it used the sole conductive additive acetylene black(AB).Such improved properties could be attributed to the partially exfoliation of AB, which not only keeps the AB's inherent advantage, but also increases the specific surface area and forms chemical bonds between carbon and sulfur, resulting in the accumulation of the polysulfides intermediate through both the physical and chemical routes.     

N- and S-doped ordered mesoporous carbon tubes with efficient S confinement for high-performance Li–S batteries

The insulating properties of S/Li₂S₂/Li₂S and the soluble Li₂S₄/Li₂S₆/Li₂S₈ obstruct the practical application of Li–S batteries. In this work, highly ordered N and S co-doped mesoporous carbon tubes (NSMCTBs) with high specific surface areas and large pore volume are employed to confine and improve the utilization efficiency of S species in Li–S batteries. The strong S_nLi₂?N interaction and S–S chemical bond between thiophenic S and Li₂S_n guarantee the exceptional electrochemical performance of as-prepared NSMCTBs/S cathode. A relatively high discharge capacity of 1315.2 mAh g^?1 is achieved for the first cycle at 0.5 C and maintained at 644.1 mAh g^?1 after 500 cycles. The NSMCTBs/S with high S content of up to 80%, it also delivers a discharge capacity of 1092.1 mAh g^?1 and considerable cycling performance. More importantly, the NSMCTBs/S can effectively suppress the self-discharge behavior of Li–S batteries.     

Synthesis and electrochemical performance of CeO2@CNTs/S composite cathode for Li–S batteries

The shuttle effect of lithium-sulfur (Li–S) battery is one of the crucial factors restraining its commercial application, because LiPSs (lithium polysulfides) usually leads to poor cycle life and low coulomb efficiency. Some studies have shown that metal oxides can adsorb soluble polysulfides. Herein, CeO₂ (cerium-oxide)-doped carbon nanotubes (CeO₂@CNTs) were prepared by the hydrothermal method. The polar metal oxide CeO₂ enhanced the chemisorption of the cathode to LiPSs and promoted the redox reaction of the cathode through catalysis properties. Meanwhile, the carbon nanotubes (CNTs) enhanced cathode conductivity and achieved more sulfur loading. The strategy could alleviate polysulfide shuttling and accelerate redox kinetics, improving Li–S batteries' electrochemical performances. As a result, the CeO₂@CNTs/S composite cathode showed the excellent capacity of 1437.6 mAh g⁻¹ in the current density of 167.5 mA g⁻¹ at 0.1 C, as well as a long-term cyclability with an inferior capacity decay of 0.17% per cycle and a superhigh coulombic efficiency of 100.434% within 300 cycles. The superior electrochemical performance was attributed to the polar adsorption of CeO₂ on polysulfides and the excellent conductivity of CNTs.

     

All-solid-state Li/S batteries with highly conductive glass–ceramic electrolytes

All-solid-state cells using sulfur-based cathode materials and Li₂S–P₂S₅ glass–ceramic electrolytes were successfully prepared and exhibited excellent cycling performance at room temperature. The cathode materials consisting of sulfur and CuS were synthesized by mechanical milling using sulfur and copper crystals as starting materials. The cell performance was influenced by the milling time for the cathode materials and the cell with cathode materials obtained by milling for 15 min retained large capacities over 650 mA h g⁻¹ for 20 cycles. Sulfur as well as CuS in cathode materials proved to be utilized as active materials on charge–discharge processes in the all-solid-state Li/S cells.     

Li10GeP2S12固态电解质电极界面特性研究

采用高温固相法合成了固态电解质Li₁₀GeP₂S₁₂,其室温离子电导率为2.02×10^-3 S/cm,并组装了LiNbO₃@LiNi_1/3Co_1/3Mn_1/3O₂/Li₁₀GeP₂S₁₂/Li全固态电池.恒流充放电测试表明全固态电池首次放电容量121.2 mAh/g,库伦效率40周后稳定在99.8%左右,循环100周后容量保持率达93.7%.电化学阻抗谱的测试结果表明,其典型的阻抗谱图由高频区半圆（HFS）、中频区半圆（MFS）和低频区斜线（LFL）组成,其中,HFS归属于电解质阻抗（R_el//Q_el）,MFS归属于电荷传递过程（R_ct//Q_dl）,LFL归属于锂离子的固态扩散过程.通过选取适当的等效电路,对实验所得的电化学阻抗谱数据进行拟合,并分析了R_el和R_ct随电极电位的变化规律.     

Recent advances on flexible electrodes for Na-ion batteries and Li–S batteries

Flexible energy storage devices are essential for emerging flexible electronics. The existing state-of-the-art Li-ion batteries are slowly reaching their limitation in terms of cost and energy density. Hence, flexible Na-ion batteries(SIBs) with abundance Na resources and Li–S batteries with high energy density become the alternative for the Li-ion batteries in future. This review summarizes the recent advances in the development of flexible electrode materials for SIBs with metallic matrix and carbonaceous matrix such as carbon nano-tubes, carbon nano-fiber, graphene, carbon cloth, carbon fiber cloth, and cotton textiles.Then, the potential prototype flexible full SIBs are discussed. Further, the recent progress in the development of flexible electrode materials for Li–S batteries based on carbon nano-fiber, carbon nano-tubes,graphene, and cotton textiles is reviewed. Moreover, the design strategies of suitable interlayer, separator,electrolyte, and electrodes to prevent the dissolution and shuttle effect of polysulfides in flexible Li–S batteries are provided. Finally some prospective investigation trends towards future research of flexible SIBs and Li–S batteries are also proposed and discussed. The scientific and engineering knowledge gained on flexible SIBs and Li–S batteries provides conceivable development for practical application in near future.     

Recent advances in chemical adsorption and catalytic conversion materials for Li–S batteries

Owing to their low cost, high energy densities, and superior performance compared with that of Li-ion batteries, Li–S batteries have been recognized as very promising next-generation batteries. However, the commercialization of Li–S batteries has been hindered by the insulation of sulfur, significant volume expansion, shuttling of dissolved lithium polysulfides(Li PSs), and more importantly, sluggish conversion of polysulfide intermediates. To overcome these problems, a state-of-the-art strategy is to use sulfur host materials that feature chemical adsorption and electrocatalytic capabilities for Li PS species. In this review, we comprehensively illustrate the latest progress on the rational design and controllable fabrication of materials with chemical adsorbing and binding capabilities for Li PSs and electrocatalytic activities that allow them to accelerate the conversion of Li PSs for Li–S batteries. Moreover, the current essential challenges encountered when designing these materials are summarized, and possible solutions are proposed. We hope that this review could provide some strategies and theoretical guidance for developing novel chemical anchoring and electrocatalytic materials for high-performance Li–S batteries.     

Recent progress in fluorinated electrolytes for improving the performance of Li–S batteries

Lithium–sulfur(Li–S) batteries represent a "beyond Li-ion" technology with low cost and high theoretical energy density and should fulfill the ever-growing requirements of electric vehicles and stationary energy storage systems. However, the sulfur-based conversion reaction in conventional liquid electrolytes results in issues like the so-called shuttle effect of polysulfides and lithium dendrite growth, which deteriorate the electrochemical performance and safety of Li–S batteries. Optimization of conventional organic solvents(including ether and carbonate) by fluorination to form fluorinated electrolytes is a promising strategy for the practical application of Li–S batteries. The fluorinated electrolytes, owing to the high electronegativity of fluorine, possesses attractive physicochemical properties, including low melting point,high flash point, and low solubility of lithium polysulfide, and can form a compact and stable solid electrolyte interphase(SEI) with the lithium metal anode. Herein, we review recent advancements in the development of fluorinated electrolytes for use in Li–S batteries. The effect of solvent molecular structure on the performance of Li–S batteries and the formation mechanism of SEI on the cathode and anode sides are analyzed and discussed in detail. The remaining challenges and future perspectives of fluorinated electrolytes for Li–S batteries are also presented.     

超球坐标下Li原子^4S态Schrodinger方程的直接解

以九维超球谐为投影函数, 构造置换群S3一维不可约表示的全反称基函数。应用HHGLF和CFHHGLF方法直接求解Li原子^4S态的Schrodinger方程。由HHGLF方法得到的本征能量与精确变分数值相差较远; CFHHGLF方法给出了与变分值相近的结果。     

Li2S-P2S5体系电解质及其在全固态锂离子电池中的应用研究进展

全固态锂离子电池具有安全性能好、能量密度高、工作温区广等优点,被广泛应用于便携式电子设备。固态电解质是全固态锂离子电池的关键材料之一,其中的硫化物电解质具有离子电导率高、电化学窗口宽、晶界电阻低和易成膜等特点,被认为最有希望应用于全固态锂离子电池。本文综述了Li_2S-P_2S_5体系电解质的发展状况,包括固态电解质的制备、改性、表征以及电极/固态电解质之间的固-固界面的稳定兼容问题。本文还涉及了以Li_2S-P_2S_5为电解质的全固态锂离子电池性能的研究进展。     

An Endogenous Prompting Mechanism for Sulfur Conversions Via Coupling with Polysulfides in Li−S Batteries

The sluggish kinetics process and shuttling of soluble intermediates present in complex conversion between sulfur and lithium sulfide severely limit the practical application of lithium-sulfur batteries. Herein, by introducing a designated functional organic molecule to couple with polysulfide intermediators, an endogenous prompting mechanism of sulfur conversions has thus been created leading to an alternative sulfur-electrode process, in another words, to build a fast “internal cycle” of promotors that can promote the slow “external cycle” of sulfur conversions. The coupling-intermediators between the functional organic molecule and polysulfides, organophosphorus polysulfides, to be the “promotors” for sulfur conversions, are not only insoluble in the electrolyte but also with higher redox-activity. So the sulfur-electrode process kinetics is greatly improved and the shuttle effect is eliminated simultaneously by this strategy. Meanwhile, with the endogenous prompting mechanism, the morphology of the final discharge product can be modified into a uniform covering film, which is more conducive to its decomposition when charging. Benefiting from the effective mediation of reaction kinetics and control of intermediates solubility, the lithium-sulfur batteries can act out excellent rate performance and cycling stability.     

Soy protein isolate/MXene decorated acidified carbon paper interlayer for long-cycling Li–S batteries

The terrible shuttling of lithium polysulfides (LiPSs) is a major obstacle for commercializing lithium–sulfur (Li–S) batteries as high-performance energy storage systems. In this study, a carbon-based interlayer with effective suppression capability on the shuttle effect is developed by simply coating a well-dispersed mixture of soybean protein isolate/MXene onto the acidified carbon paper (ACP). The resultant composite interlayer (SM@ACP) is able to synergistically diminish the shuttle effect through chemical adsorption and physical blocking. Meanwhile, this interlayer displays excellent conductivity and facilitates the diffusion of Li ions due to the composite coating to promote both electron/ion conduction as well as the porous structure of ACP. Benefiting from the unique properties of the composite interlayer, the as-assembled Li–S batteries with SM@ACP interlayers show a great improvement in the cycling stability and rate performance, delivering a very low-capacity decay rate of 0.071% per cycle at 0.5 C even after 800 cycles. This work provides a feasible route to realize rational design and commercial mass production of desirable interlayers for promoting the commercialization of Li–S batteries.     

Chemistry-Performance Relationships of Polymer Gel-Electrolytes for Mg−S and Li−S Batteries: Influence of Network Cation Solvation Capacity on Polymer-Polysulfide Interactions

Metal-sulfur batteries are a promising next-generation energy storage technology, offering high theoretical energy densities with low cost and good sustainability. An active area of research is the development of electrolytes that address unwanted migration of sulfur and intermediate species known as polysulfides during operation of metal-sulfur batteries, a phenomenon that leads to low energy efficiency and short life-spans. A particular class of electrolytes, gel polymer electrolytes, are especially attractive for their ability to repel polysulfides on the basis of structure, electrostatics, and other polymer properties. Herein, within the context of magnesium- and lithium-sulfur batteries, we investigate the impact of gel polymer electrolyte cation solvation capacity, a property related to network dielectric constant and chemistry, on sulfur/polysulfide-polymer interactions, an understudied property-performance relationship. Polymers with lower cation solvation capacity are found to permanently absorb less polysulfide active material, which increases sulfur utilization for Li−S batteries and significantly increases charge efficiency and life-span for Li−S and Mg−S batteries.     

Li/Li(100)面自扩散体系的理论研究

本文应用对势方法构造了Li/Li(100)表面缺陷体系的吸附扩散相互作用模型势,考察了各种台阶、扭结、空位等表面缺陷对锂原子表面吸附扩散行为的影响。根据缺陷表面体系结合能和表面扩散活化势垒的结果,提出和分析了捕获能力和捕获网链的概念。     

Li2MnBr4(o-rh.) – eine geordnete NaCl-Defektstruktur des SnMn2S4-Typs

Li₂MnBr₄(o-rh.) – an Ordered NaCl Defect Structure of the SnMn₂S₄ Type Neutron diffraction data of Li₂MnBr₄ at 25°C are presented. The orthorhombic room-temperature polymorph of Li₂MnBr₄ (space group Cmmm, Z = 2, a = 777.78(4), b = 1106.58(5), and c = 388.18(2) pm, R_I = 6.7%) crystallizes in an ordered NaCl defect structure (SnMn₂S₄ type). The tetragonally distorted MBr₆ octahedra are elongated in the case of LiBr₆ and compressed for MnBr₆ owing to the different sharing of these units. The crystal structure of Li₂MnBr₄ oC14 (and those of alternative structure models with a larger pseudotetragonal cell) are discussed with respect to X-ray intensities, Madelung part of lattice energy (MAPLE), and the Raman spectra. The symmetry coordinates and vibrational modes of the \documentclass{article}\pagestyle{empty}\begin{document}$ (\mathop {\rm k}\limits^ \to = 0) $\end{document} phonons of Li₂MnBr₄ oC14 are given.     

Self-assembled Li4Ti5O12/TiO2/Li3PO4 for integrated Li–ion microbatteries

This work aims to maximize the number of active sites for energy storage per geometric area, by approaching the investigation to 3D design for microelectrode arrays. Self-organized Li₄Ti₅O₁₂/TiO₂/Li₃PO₄ composite nanoforest layer (LTL) is obtained from a layer of self organized TiO₂/Li₃PO₄ nanotubes. The electrochemical response of this thin film electrode prepared at 700 °C exhibited lithium insertion and de-insertion at 1.55 and 1.57 V respectively, which is the typical potential found for lithium titanates. The effects of lithium phosphate on lithium titanate are explored for the first time. By cycling between 2.7 and 0.75 V the LTL/LiFePO₄ full cell delivered 145 mA h g^− 1 at an average potential of 1.85 V leading to an energy density of 260 W h kg^− 1 at C/2. Raman spectroscopy revealed that the γ-Li₃PO₄/lithium titanate structure is preserved after prolonged cycling. This means that Li₃PO₄ plays an important role for enhancing the electronic conductivity and lithium ion diffusion.