Poly(2,5‐dimercapto‐1,3,4‐thiadiazole) as a Cathode for Rechargeable Lithium Batteries with Dramatically Improved Performance

Organosulfur compounds with multiple thiol groups are promising for high gravimetric energy density electrochemical energy storage. We have synthesized a poly(2,5‐dimercapto‐1,3,4‐thiadiazole) (PDMcT)/poly(3,4‐ethylenedioxythiophene) (PEDOT) composite cathode for lithium‐ion batteries with a new method and investigated its electrochemical behavior by charge/discharge cycles and cyclic voltammetry (CV) in an ether‐based electrolyte. Based on a comparison of the electrochemical performance with a carbonate‐based electrolyte, we found a much higher discharge capacity, but also a very attractive cycling performance of PDMcT by using a tetra(ethylene glycol) dimethyl ether (TEGDME)‐based electrolyte. The first discharge capacity of the as‐synthesized PDMcT/PEDOT composite approached 210 mAh g^?1 in the TEGDME‐based electrolyte. CV results clearly show that the redox reactions of PDMcT are highly reversible in this TEGDME‐based electrolyte. The reversible capacity remained around 120 mAh g^?1 after 20 charge/discharge cycles. With improved cycling performance and very low cost, PDMcT could become a very promising cathode material when combined with a TEGDME‐based electrolyte. The poor capacity in the carbonate‐based electrolyte is a consequence of the irreversible reaction of the DMcT monomer and dimer with the solvent, emphasizing the importance of electrolyte chemistry when studying molecular‐based battery materials.     

Poly(2,5-dimercapto-1,3,4-thiadiazole) as a cathode for rechargeable lithium batteries with dramatically improved performance

Organosulfur compounds with multiple thiol groups are promising for high gravimetric energy density electrochemical energy storage. We have synthesized a poly(2,5-dimercapto-1,3,4-thiadiazole) (PDMcT)/poly(3,4-ethylenedioxythiophene) (PEDOT) composite cathode for lithium-ion batteries with a new method and investigated its electrochemical behavior by charge/discharge cycles and cyclic voltammetry (CV) in an ether-based electrolyte. Based on a comparison of the electrochemical performance with a carbonate-based electrolyte, we found a much higher discharge capacity, but also a very attractive cycling performance of PDMcT by using a tetra(ethylene glycol) dimethyl ether (TEGDME)-based electrolyte. The first discharge capacity of the as-synthesized PDMcT/PEDOT composite approached 210 mAh g(-1) in the TEGDME-based electrolyte. CV results clearly show that the redox reactions of PDMcT are highly reversible in this TEGDME-based electrolyte. The reversible capacity remained around 120 mAh g(-1) after 20 charge/discharge cycles. With improved cycling performance and very low cost, PDMcT could become a very promising cathode material when combined with a TEGDME-based electrolyte. The poor capacity in the carbonate-based electrolyte is a consequence of the irreversible reaction of the DMcT monomer and dimer with the solvent, emphasizing the importance of electrolyte chemistry when studying molecular-based battery materials.     

Amorphous Selenium and Crystalline Selenium Nanorods Graphene Composites as Cathode Materials for All-Solid-State Lithium Selenium Batteries

Selenium (Se) is an element in the same main group as sulfur and is characterized by high electrical conductivity and large capacity (675 mAh g⁻¹). Herein, a novel ultra-high dispersion amorphous selenium graphene composite (a-Se/rGO) was synthesized and a selenium nanorods graphene composite (b-Se/rGO) was prepared by hydrothermal method as the cathode material for all solid-state lithium−selenium (Li−Se) batteries, hoping to improve the efficiency and utilization rate of active substances in all solid-state batteries. The all-solid-state batteries were assembled using a heated thawing electrolyte (2LiIHPN−LiI; HPN=3-hydroxypropionitrile). The utilization rate of a-Se/rGO was 103 % and the capacity was 697 mAh g⁻¹, which remained at 281 mAh g⁻¹ (41.6 % of the 675 mAh g⁻¹) after 30 cycles under 0.5 C. Notably, a-Se/rGO showed excellent performance concerning its utilization rate, with a capacity of up to 610 mAh g⁻¹ at 2 C, due to the high availability of amorphous Se and the special properties of the electrolytes. However, in the charge and discharge cycles, the second discharge capacity of a-Se/rGO was more significantly attenuated than that of the first discharge due to the formation of larger crystals of selenium during the charging process. The battery assembled using b-Se/rGO maintained a capacity of 270.58 mAh g⁻¹ after 30 cycles (the retention rate of discharge capacity was 66.13 % compared with that in the first cycle). Through TEM and other relevant tests, it is speculated that amorphous selenium is conducive to capacity release, which, however, is affected by the formation of crystalline selenium after the first charge process.     

Synthesis and electrochemical characteristics of xLi2MnO3–(1−x)Li(Mn0.375Ni0.375Co0.25)O2 (0.0 ≤ x ≤ 1.0) thin film cathode for lithium rechargeable micro batteries

We have compared the structure, microstructure, and electrochemical characteristics of xLi₂MnO₃–(1−x)Li(Mn_0.375Ni_0.375Co_0.25)O₂ (0.0 ≤ x ≤ 1.0) thin films with their bulk cathode laminate counterparts of identical compositions. Pure Li(Mn_0.375Ni_0.375Co_0.25)O₂ as well as the synthesized composite films partially transform into cubic spinel structure during charge–discharge cycling. In contrast, such layered to spinel phase transformation has only been identified in bulk cathode laminates with x ≥ 0.75. At a current density 0.05 mAcm⁻², the discharge capacity of Li(Mn_0.375Ni_0.375Co_0.25)O₂ thin film was measured to be ∼60 μAhcm⁻². The discharge capacity (∼217 μAhcm⁻²) was markedly improved in x∼0.5 composite thin film. The capacity retention after 20 charge discharge cycles are improved in composite films; however, their capacity fading could not be eliminated completely.     

Catalytically Active CoSe2 Supported on Nitrogen-Doped Three Dimensional Porous Carbon as a Cathode for Highly Stable Lithium-Sulfur Battery

Lithium-sulfur batteries are promising secondary energy storage devices that are mainly limited by its unsatisfactory cyclability owing to inefficient reversible conversion of sulfur and lithium sulfide on the cathode during the discharge/charging process. In this study, nitrogen-doped three-dimensional porous carbon material loaded with CoSe₂ nanoparticles (CoSe₂-PNC) is developed as a cathode for lithium-sulfur battery. A combination of CoSe₂ and nitrogen-doped porous carbon can efficiently improve the cathode activity and its conductivity, resulting in enhanced redox kinetics of the charge/discharge process. The obtained electrode exhibits a high discharge specific capacity of 1139.6 mAh g⁻¹ at a current density of 0.2 C. After 100 cycles, its capacity remained at 865.7 mAh g⁻¹ thus corresponding to a capacity retention of 75.97 %. In a long-term cycling test, discharge specific capacity of 546.7 mAh g⁻¹ was observed after 300 cycles performed at a current density of 1 C.     

Well-dispersed sulfur anchored on interconnected polypyrrole nanofiber network as high performance cathode for lithium-sulfur batteries

Preparation of novel sulfur/polypyrrole (S/PPy) composite consisting well-dispersed sulfur particles anchored on interconnected PPy nanowire network was demonstrated. In such hybrid structure, the as-prepared PPy clearly displays a three-dimensionally cross-linked and hierarchical porous structure, which was utilized in the composite cathode as a conductive network trapping soluble polysulfide intermediates and enhancing the overall electrochemical performance of the system. Benefiting from this unique structure, the S/PPy composite demonstrated excellent cycling stability, resulting in a discharge capacity of 931 mAh g⁻¹ at the second cycle and retained about 54% of this value over 100 cycles at 0.1 C. Furthermore, the S/PPy composite cathode exhibits a good rate capability with a discharge capacity of 584 mAh g⁻¹ at 1  C.     

Cathode material for sodium-ion batteries based on manganese hexacyanoferrate: the role of the binder component

Sodium manganese hexacyanoferrate (NaMnHCF) was synthesized by a hydrothermal method and investigated as a cathode material for sodium-ion batteries. The morphology and the structure of NaMnHCF were investigated by X-ray diffraction, scanning electron microscopy, and EDX analysis. New composition of NaMnHCF cathode material for sodium-ion batteries with eco-friendly water-based binder consisting of conducting polymer poly-3,4-ethylenedioxythiopene/polystyrene sulfonate (PEDOT:PSS) dispersion and carboxymethyl cellulose (СМС) was proposed. The electrochemical properties of NaMnHCF cathode material with conductive polymer binder were investigated by cyclic voltammetry and galvanostatic charge-discharge, and the results were compared with the performance of a conventional PVDF-bound material. It was shown that the initial discharge capacity of electrodes with conductive binder is 130 mAh g⁻¹, whereas the initial discharge capacity of PVDF-bound electrodes was 109 mAh g⁻¹ (both at current density 120 mA g⁻¹, values normalized by NaMnHCF mass). The material with conductive binder also has better rate capability; however, it is losing in cycling capability to the electrode composition with conventional PVDF binder.

     

SnNi-deposited carbonaceous mesophase spherule as anode material for lithium ion batteries

Carbonaceous mesophase spherule (CMS) is a commercial anode material for rechargeable lithium batteries. A composite anode material of SnNi deposited carbonaceous mesophase spherule was prepared by co-precipitation method. The structural and electrochemical characterization of the SnNi/CMS composite anode material was studied. According to the measurement of its electrochemical characterization, the prepared SnNi/CMS composite anode material shows much better electrochemical performance than CMS. The first discharge capacity of 360 mA h g⁻¹ was obtained for the SnNi/CMS composite anode material, and its discharge capacity maintained at 320–340 mA h g⁻¹ in the following cycles. It indicates that the modification of CMS with SnNi alloy can further improve the intercalation performance of CMS. SnNi/CMS composite material shows a good candidate anode material for the commercial rechargeable lithium batteries.     

Room temperature Na/S batteries with sulfur composite cathode materials

Sodium/sulfur (Na/S) batteries were assembled with a sodium metal anode, liquid electrolyte and a sulfur composite cathode. Their electrochemical characteristics have been investigated at room temperature. Their charge/discharge curves indicate that sodium can reversibly react with sulfur at room temperature. The specific capacity of the sulfur composite cathode material in the first cycle was initially about 655 mA h g⁻¹ and stayed at about 500 mA h g⁻¹ up to the 18th cycle with about 100% charge/discharge efficiency.     

Amorphous MnO2 as Cathode Material for Sodium‐ion Batteries

Amorphous MnO₂ has been prepared from the reduction of KMnO₄ in ethanol media by a facile one‐step wet chemical route at room temperature. The electrochemical properties of amorphous MnO₂ as cathode material in sodium‐ion batteries (SIBs ) are studied by galvanostatic charge/discharge testing. And the structure and morphologies of amorphous MnO₂ are investigated by X‐ray diffraction (XRD ), scanning electron microscopy (SEM ), transmission electron microscopy (TEM ) and Raman spectra. The results reveal that as‐synthesized amorphous MnO₂ electrode material exhibits a spherical morphology with a diameter between 20 and 60 nm. The first specific discharge capacity of the amorphous MnO₂ electrode is 123.2 mAh •g⁻¹ and remains 136.8 mAh •g⁻¹ after 100 cycles at the current rate of 0.1 C. The specific discharge capacity of amorphous MnO₂ is maintained at 139.2, 120.4, 89, 68 and 47 mAh •g⁻¹ at the current rate of 0.1 C, 0.2 C, 0.5 C, 1 C and 2 C, respectively. The results indicate that amorphous MnO₂ has great potential as a promising cathode material for SIBs .     

Nitrogen-Linked Hexaazatrinaphthylene Polymer as Cathode Material in Lithium-Ion Battery

Nitrogen-linked hexaazatrinaphthylene polymer ( N²-HATN ) as organic cathode material with low HOMO–LOMO gap was synthesized and was observed to possess reversible high capacity and unexpected long-term cycling stability. The pre-treated N²-HATN and pRGO combination demonstrated good structure compatibility and the resultant cathode exhibited a constant increment of capacity during the redox cycles. The initial capacity at 0.05 A g⁻¹ was 406 mA h⁻¹ g⁻¹, and increased to 630 mA h⁻¹ g⁻¹ after 70 cycles. At 0.5 A g⁻¹ discharging rate, the capacity increased from an initial value of 186 mA h⁻¹ g⁻¹ to 588 mA h⁻¹ g⁻¹ after 1600 cycles. The pseudocapacitance-type behavior is postulated to be attributed to the structure compatibility between the active material and pRGO.     

A ZIF-8 Host for Dendrite-Free Zinc Anodes and N,O Dual-doped Carbon Cathodes for High-Performance Zinc-Ion Hybrid Capacitors

Zn is a promising anode for aqueous energy storage owing to it intrinsic superior properties such as large capacity, abundant reserves, low potential and safety. But, the growth of dendrites during charge and discharge leads to a decrease in reversibility. In addition, further development of zinc-ion hybrid capacitors (ZICs) is seriously challenging because of the lack of an exceptional cathode. Herein, we use ZIF-8 annealed at 500 °C (annealed ZIF-8) as a host material for stable and dendrite-free Zn anodes. Utilization of annealed ZIF-8 results in dendrite-free Zn deposition and stripping as a result of its porous construction, which contains trace Zn. Furthermore, we firstly proposed innovative N,O dual-doped carbon which was designed by the derived ZIF-8 (ZIF-8 derived C) as cathode for high-energy and power-density ZICs. The new ZIC assembled by Zn@annealed ZIF-8 anode and ZIF-8 derived C cathode provides a capacity of 135.5 mAh g⁻¹ and an energy density of 108.4 Wh kg⁻¹ with a power density of 800 W kg⁻¹ at 1.0 A g⁻¹. In addition, it shows outstanding cycling stability of 91% capacity retention after 6000 cycles at 5.0 A g⁻¹. Moreover, the solid-state ZICs can drive LEDs and smart watches. This ZIC holds promise for the practical application of supercapacitors.     

Fabrication of a Practical and Polymer‐Rich Organic Radical Polymer Electrode and its Rate Dependence

A practical and polymer‐rich organic radical cathode that contains 80 wt.‐% poly(4‐vinyloxy‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl) (PTVE) and 15 wt.‐% vapor‐grown carbon fiber (VGCF) has been fabricated. The PTVE/VGCF composite electrode shows a reversible redox peak at 3.56 V (vs Li/Li⁺) in cyclic voltammetry. A coin‐type cell with the PTVE/VGCF composite electrode as the cathode and lithium metal as the anode has also been fabricated and used for charge/discharge measurements. When the cell was discharged at 0.3 mA · cm⁻² (1 C), a capacity of 104 mAh · g⁻¹, which is 77% of PTVE's theoretical capacity (135 mAh · g⁻¹), was obtained. When it was discharged at 9.0 mA · cm⁻² (30 C), its capacity was 52% of the capacity it had when it was discharged at 0.3 mA · cm⁻² (1 C). Even when discharged at 24 mA · cm⁻² (80 C), it surprisingly had 32% of the capacity it had when discharged at 0.3 mA · cm⁻². The observed rate dependence shows that the polymer‐rich electrode could discharge over 50% of the cell capacity in two minutes and over 30% within one minute.

     

脉冲激光沉积法制备FeSe薄膜电极及其电化学性质

采用脉冲激光溅射Fe和Se粉末的混合靶制备FeSe薄膜并用XRD、充放电和循环伏安测试研究了薄膜的结构和电化学性质. XRD结果显示, 当基片温度为200 ℃时, 薄膜主要由晶态的FeSe组成. 在电压1.0～3.0 V范围内, 该薄膜的可逆容量为360.8 mAh•g^－1, 经过100次循环之后的放电容量为396.5 mAh•g^－1, 具有很好的循环性能. ex situ XRD结果显示FeSe能够和Li发生可逆的电化学反应, 颗粒尺寸大于5 nm的纳米铁颗粒能够驱动Li₂Se的分解并在充电过程中重新生成FeSe. FeSe具有较高的可逆容量和较好的循环性能, 可能成为一种优良的锂二次电池正极材料.     

Layer-By-Layer (LBL) hybrid MOF coating for graphene-based multilayer composite: Synthesis and application as anode for lithium ion batteries

The hybrid anodic materials with high porosity and low charge resistance exhibit high specific capacity and stable cyclic stability for lithium ion battery (LIBs). For this purpose, three-dimensional hollow material, metal organic framework (MOF-199) was coated over the active surface of oxidized derivative of graphene (Graphene oxide, GO), via layer-by-layer (LBL) coating method. Cupric acetate and benzene-1,3,5-tricarboxylic acid [Cu₃(BTC)₂], were alternatively coated on the active surface of GO as an anode material, to enhance the structural diversity and reduce the synergistic effect of insertion and extraction of Li⁺ ions for LIBs. Sharp absorption peaks from 1620 cm⁻¹ to 1360 cm⁻¹ and intense ring bends ∼1000 cm⁻¹ was identified through FTIR. Powder XRD provides the evidence for size reduction of Cu₃(BTC)₂@GO composite (32.6 nm) comparative to GO (43.7 nm). Outcome of EIS analysis shows the charge transfer resistance of simple GO is 2410 Ω, which is 4 times higher than R_ct of Cu₃(BTC)₂@GO composite (590 Ω). Similarly the Warburg impedance co-efficient for simple GO (448.8 Ωs^−1/2) is also higher than A_w of Cu₃(BTC)₂@GO composite (77.64 Ωs^−1/2). The synthesized material show high initial charge/discharge capacity, 1200/1420 mAh/g with 85% Coulombic efficiency and reversible discharge capacity, 1296 mAh/g after 100 cycles at 100 mA/g current density. The 98.9% Coulombic efficiency and 91% retaining capacity of composite at 100th cycle with cyclic stability, provides the phenomenon approach towards the rechargeable LIBs for industrial technology.     

Investigation of immiscible alloy system of Al–Sn thin films as anodes for lithium ion batteries

The Al–Sn, which is immiscible alloy, film was prepared by e-beam deposition to explore the possibility as anode material for lithium ion batteries for the first time. The film has a complex structure with tiny Sn particles dispersed homogeneously in the Al active matrix. The diffusion coefficients of Li⁺ in these Al–Sn alloy films were determined to be 2.1–3.2 × 10⁻⁸ cm²/s by linear sweep voltammetry. The film electrode with high Al content (Al–33wt%Sn) delivered a high initial discharge capacity of 972.8 mA h g⁻¹, while the film electrode with high Sn content (Al–64wt%Sn) with an initial discharge capacity of 552 mA h g⁻¹ showed good cycle performance indicated by retaining a capacity of about 381 mA h g⁻¹ after 60 cycles. Our preliminary results demonstrate that Al–Sn immiscible alloy is a potential candidate for anodic material of lithium ion batteries.     

Hierarchical porous carbon/selenium composites derived from abandoned paper cup as Li-Se battery cathodes

Paper cup composed of crude cellulose is a common waste in daily life. In this paper, hierarchical porous carbons have been successfully prepared by an initial hydrothermal treatment and subsequent activation route from abandoned paper cup, and then paper cup derived carbons are used as scaffolds to fabricate serial carbon/Se composites. The optimal composite presents unique 3D porous structure, with amorphous selenium uniformly confined into the micropores of carbon. As the cathode materials of Li-Se battery, this composite reveals an initial reversible discharge capacity of 517.2 mAh g⁻¹ at 0.2C, and a capacity value of 431.9 mAh g⁻¹ can be retained after 60 cycles. Even at a high rate of 4C, a capacity value of 295.8 mAh g⁻¹ can be obtained. By comparison, the improved electrochemical performance of the optimal composite should be attributed to reasonable porous structure and effective encapsulation of amorphous selenium.     

AlF3包覆对Li1.2Mn0.534Ni0.133Co0.133O2正极材料电化学性能的影响

通过共沉淀法制备锂离子电池富锂锰基正极材料Li1.2Mn0.534Ni0.133Co0.133O2,并对其进行AlF3包覆。实验结果表明,通过AlF3包覆,材料的电化学性能得到明显提高。在0.2C下,包覆前材料的首次放电比容量为253 mAh.g-1,首次充放电效率仅为88.8%。经过AlF3包覆,材料的首次放电比容量提高到294 mAh.g-1,首次充放电效率高达96.4%。同样,在1.0C下循环50次,未包覆材料的放电比容量由225 mAh.g-1降到185 mAh.g-1,容量保持率仅为82.2%。经过AlF3包覆,材料的放电比容量由230mAh.g-1仅降为222 mAh.g-1,容量保持率高达96.5%。     

Scalable Synthesis of Porous SiFe@C Composite with Excellent Lithium Storage

Utilizing cost-effective raw materials to prepare high-performance silicon-based anode materials for lithium-ion batteries (LIBs) is both challenging and attractive. Herein, a porous SiFe@C (pSiFe@C) composite derived from low-cost ferrosilicon is prepared via a scalable three-step procedure, including ball milling, partial etching, and carbon layer coating. The pSiFe@C material integrates the advantages of the mesoporous structure, the partially retained FeSi₂ conductive phase, and a uniform carbon layer (12–16 nm), which can substantially alleviate the huge volume expansion effect in the repeated lithium-ion insertion/extraction processes, effectively stabilizing the solid–electrolyte interphase (SEI) film and markedly enhancing the overall electronic conductivity of the material. Benefiting from the rational structure, the obtained pSiFe@C hybrid material delivers a reversible capacity of 1162.1 mAh g⁻¹ after 200 cycles at 500 mA g⁻¹, with a higher initial coulombic efficiency of 82.30 %. In addition, it shows large discharge capacities of 803.1 and 600.0 mAh g⁻¹ after 500 cycles at 2 and 4 A g⁻¹, respectively, manifesting an excellent electrochemical lithium storage. This work provides a good prospect for the commercial production of silicon-based anode materials for LIBs with a high lithium-storage capacity.     

涂碳铝箔对磷酸铁锂电池性能影响研究

本文研究了使用涂碳铝箔作为正极集流体磷酸铁锂电池的性能。研究对比了使用普通铝箔和涂层铝箔的10 Ah软包磷酸铁锂电池的主要性能。研究表明：使用涂层铝箔不但可以提高磷酸铁锂材料的粘结性,而且使用导电涂层可以有效降低正极材料和集流体的接触内阻,从而减小电池内阻,提高电池倍率性能。与使用普通铝箔作为集流体相比,通过使用涂碳铝箔可以使得电池的内阻降低65%左右,但是,磷酸铁锂正极材料的克容量却偏低约5~10 mAh·g^-1,首次效率也偏低4%左右;在快速放电15C倍率下,使用涂碳铝箔的电芯比使用普通铝箔容量提高约15%左右,10C放电倍率下,平台增加0.3~0.4 V;使用涂碳铝箔电芯的常温自放电率较高,但容量恢复率也较高;550周循环下,使用涂碳铝箔可以使得电池的循环性能提高约1%。而在电池低温性能方面,使用涂碳铝箔对低温性能并无改善。