Developing carbonyl-based organic electrodes with multi-active sites is crucial for advancing aqueous zinc-ion batteries (AZIBs), but a fundamental understanding of their charge-storage mechanism remains elusive. Herein, we elucidate this mechanism through the molecular design of a conjugated carbonyl compound (DHB) and its oxidized-derivative (o-DHB). While DHB undergoes a 4-electron storage process, strategic oxidation expands this to a reversible 6-electron process in o-DHB. Remarkably, the resultant Zn||o-DHB battery delivers an exceptional specific capacity of 323 mAh g- 1 even at a high current density of 5 A g- 1 and retains 71% of its capacity after 3,500 cycles, outperforming most reported organic AZIBs. Combined electrochemical and spectroscopic comparative analyses reveal that the high oxidation potential of terminal ortho-hydroxyl groups (C & horbar;O & horbar;H) in DHB inhibits their full utilization. In contrast, o-DHB enables the reversible reduction of both ortho- and para-C = O groups at relatively low potentials to form C & horbar;O & horbar;Zn bonds, confirming Zn2+ migration-not H+ insertion-as the dominant charge-storage mechanism. Theoretical calculations further demonstrate that the oxidation engineering lowers the LUMO energy and narrows the HOMO-LUMO gap of o-DHB, promoting electron delocalization, enhancing conductivity, and accelerating reaction kinetics. This work provides profound mechanistic insights and establishes a molecular design principle for developing high-performance organic cathodes for AZIBs.

The sulfured dicyclopentadiene (S-DCPD) is a promising cathode candidate for Li-S batteries. Enlightened by the function of KI in dye-sensitized solar cells, we employ KI as a catalyst in the preparation of S-DCPD without eliminating it in the assembly of Li-S batteries. As a result, the sulfurizing reaction proceeds more completely at a lower temperature. The as-prepared material exhibits a different light response to the blank sample, changing from a higher energy level to a lower one. And the electrochemistry is greatly elevated as well. Theoretical calculations validate that KI plays the key role by altering the electron transmitting path. We can thus unify the behaviors of KI in the field of heat, light, and electricity, phenomenally. Furthermore, we investigate the morphology changes of the electrode by dipping it in an ordinary solution and subjecting it to a cycle calendar life in the electrolyte, respectively. As a result, we make clear that the difference of the behaviors between ordinary solutions and electrolytes is also in associated with the electronic path of KI.

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The limited conductivity and shuttle effect tie the sulfur cathode down. Carbon nanofibers (CNFs) offer long-range conductivity with cost effectiveness but fail for the wanted backing since they are intertwined with each other, which makes it difficult for sulfur to permeate the mass of the CNF matrix. Dissolving or melting sulfur and immersing it in the bulk of CNFs cannot avoid sulfur segregation. By nanosizing sulfur and loading it into the bulk of the CNFs with the assistance of surfactants, we propose a microreactor strategy to address these challenges. Due to the spatial constraints within the S@CNF microreactors, the nanostructured sulfur can be sintered at high temperatures without significant mass loss. As a result, not only is the electrical conductivity improved but also the shuttle effect is obviously confined in microreactors, enhancing cycle performance at an elevated S/C ratio of 8:2. The diffusion coefficient and activation energy characterized by the Randles-Sevcik equation and operando approaches, respectively, validate the enhancement of dynamics, which can be ascribed to the promoting effect of electronic transitions on ionic diffusion. The analysis of optical and electrochemical band gaps confirms this point of view. Thereby, using the microreactor strategy, we turn the adverse mass of the CNFs into favorable factors.

通过溶胶-凝胶法和高温固相法,将负热膨胀材料ZrV2O7包覆在硅微粉表面.结果表明:负热膨胀材料ZrV2O7能有效地改善界面稳定性,提升循环性能.当与碳材料进一步结合,构建C-ZrVO27复合包覆层时,发现负热膨胀材料和碳具有协同作用.C-ZrV2O7包覆层在循环过程中与硅结合得更紧密,从而有效地抑制了硅负极与电解液的反应.改性后的材料有更高的可逆比容量和循环稳定性,在0.1C的放电倍率下,循环120周后放电比容量仍能稳定在500mAh/g以上,接近于纳米硅材料,显示出一定的工业应用价值.

Abstract: The capacity of cathode materials is one of the main factors to limit the performance of lithium-ion batteries (LIBs), so it is urgent to develop high-performance cathode materials. Herein, trinitrohexaazatrinaphthalene (TNHATN) including an electron-withdrawing group (nitro, -NO2) was synthesized by the condensation reaction between hexaketocyclohexane and 4-nitro-o-phenylenediamine, and it was first investigated as a cathode material for lithium-ion batteries. The TNHATN electrode displays a high discharge specific capacity of 361.7 mAh g-1 at 0.05 A g-1 and a superior cycling stability, remaining the capacity retention of 97.9 % after 200 cycles. The excellent behaviors may be ascribed to its π-conjugated structure including electron-withdrawing groups and multiple redox active sites. The experimental resultes reveal the redox active sites are pyrazine nitrogen atoms and oxygen atoms from nitrio groups. This work confirms that it is an effective route to introduce an electron-withdrawing group into a π-conjugated compound for obtaining high-performance organic cathode materials of LIBs.

Lithium polysulfide intermediates suffer from serious "shuttle effect" and slow redox kinetics, resulting in limited rate performance, low discharge capacity and rapid capacity decay of lithium-sulfur (Li-S) batteries. Here, we propose a concept of cluster-type lithium polysulfides (LiPSs) regulator to address the above-mentioned problems. Dipyridyl disulfide (DpyDS) is introduced to be an electrolyte additive to form low solubility macromolecular lithium pyridine-2-thiolate (LiPyS) clusters in electrolyte by in-situ lithiation and Li bond network. The LiPyS monomer in the clusters form complexes (LiPyS-LiPSs) with LiPSs through bi-directional Li center dot center dot center dot S bonds, so as to restrict LiPSs to the clusters on the cathode side, preventing the parasitic reaction between LiPSs and Li metal. At the same time, LiPyS-LiPSs have higher HOMO energy levels and lower LUMO energy levels than that of single LiPSs. As a result, LiPSs can achieve an enhanced redox activity, and the Li-S battery regulated with DpyDS provides a capacity as high as 900 mA h g(-1) at 2 C rate.

采用热熔法在185℃下使单质硫(S8)发生开环反应得到线性硫,然后再与有机材料双环戊二烯(DCPD)进行耦合,使线性硫接枝到双环戊二烯上,得到新型富硫的有机聚合材料(S-DCPD).通过核磁、拉曼、X射线衍射和x射线光电子能谱表征证实单质硫接枝到双环戊二烯上面.这种以化学键方式固定单质硫的方法,有效地缓解了锂-硫电池中的"穿梭效应"问题.合成了一系列具有不同硫含量的S-DCPD材料,其中60％硫含量的S-DCPD综合电化学性能最优,库仑效率达到98％以上.

Inhibiting the shuttle effect caused by soluble lithium polysulfides (LiPSs) is of importance for lithium-sulfur (Li-S) batteries. Here, a strategy was developed to construct protective layers by self-assembly networks to regulate the LiPSs. 2,5-Dichloropyridine (25DCP) holds two kinds of functional groups. Among them, the two C-Cl bonds were nucleophilic substituted by S in LiPSs to form long chains. The pyridine N interacted with Li in other LiPSs via Li bonds to form a short chain. As a result, the long chains were cross-linked by the short chain to form an insoluble network. The as-prepared network covered the sulfur electrode interface to suppress the shuttle effect of the subsequently generated LiPSs. Furthermore, 25DCP improved the redox dynamics by changing the energy level and electronic structure of the sulfur species. Therefore, the Li-S batteries with 25DCP exhibited good electrochemical performance. This work provides a feasible strategy for regulating the LiPSs.

Aqueous zinc batteries are considered as one of the most promising energy storage systems for large-scale energy storage and wearable electronics, owing to their low cost and intrinsic safety. However, developing high-performance cathode materials with environmentally friendly is still an important task. Here, we demonstrate that two N-containing organic compounds, hexamethoxy hexaazatrinaphthylene (HMHATN) and hexaazatrinaphthylene (HATN), used as cathodes can exhibit high capacity with fast kinetics. Thus, the Zn//HMHATN and Zn//HATN full batteries display the high energy density of 160 and 221.6 W h Kg(-1), respectively, and long-term cycling stability. Electrochemical analysis, density functional theory calculation and ex situ analysis identify that the organic cathodes involve uptake and removal of Zn2+ and H+ in the discharging-charging process. Furthermore, the flexible aqueous Zn//HMHATN and Zn//HATN batteries fabricated also have high capacity, long-term cycling life and impressive energy density, displaying its application prospect in wearable electronics.

Lithium-sulfur (Li-S) battery is one of the most promising candidates for the next generation energy storage systems. However, the inherent slow redox kinetics of sulfur leads to limited rate performance, low discharge capacity and rapid capacity fading. Herein, the Li1+xMn2O4 material produced by in-situ lithium intercalation of LiMn2O4 before 2.5 V is selected to improve the performances of Li-S batteries. First-principles calculations show that Li1+xMn2O4 can improve electronic conductivity and chemical adsorption. Electrochemical characterizations further confirm that lithiated material provides a fast conversion kinetics for LiPSs and a low barrier of lithium-ion diffusion. As a result, the Li-S battery incorporating Li1+xMn2O4 presents excellent rate performance with a discharge capacity as high as 915 mAh g(-1) at 2 C rate. At the same time, the battery maintains a high reversible capacity of 531 mAh g(-1) after 1000 cycles at 1 C rate, and the average capacity loss per cycle is only 0.047%. This work can improve the redox kinetics of sulfur cathodes and provide a new path for the advancement of high-performance Li-S batteries. (c) 2021 Elsevier Ltd. All rights reserved.

A facile strategy to synthesize organic cathode material using triquinoxaline (3Q) and elemental sulfur (S) is reported. The 3Q material is a kind of multiredox phase‐transiting composite with a theoretical specific capacity of 418 mA h g −1 and a poor cycling performance. By adding S to 3Q@multiwalled carbon nanotubes (MWCNTs) at 165 °C with a mass ratio of 1:4, S and 3Q are chemically matched to form an organic composite S‐3Q@MWCNT. Interestingly, it is found that the as‐prepared sample exhibits a single‐electrochemical phase transition with a higher specific capacity of 608 mA h g −1 at 0.1C rate. The mass ratio of 1:4 indicates that the capacity of S is equal to the capacity of 3Q, and the monoredox conversion phase suggests that S and 3Q are electrochemically matched. These results show that the chemical matching point is consistent with the electrochemical matching point. The as‐prepared S‐3Q@MWCNT composite presents a good cycling performance. In the absence of any additives, especially without the assistance of coated separators, the coulombic efficiency is stable at around 100% for 400 cycles. It is believed that the monophase redox process of the as‐prepared S‐3Q@MWCNT improves the cycling performance.

Aqueous zinc batteries are considered as one of the most promising energy storage systems for large-scale energy storage and wearable electronics, owing to their low cost and intrinsic safety. However, cathode materials that can reversibly host Zn2+ are still less. Here, we demonstrate that two N-containing organic compounds, hexamethoxy hexaazatrinaphthylene (HMHATN) and hexaazatrinaphthylene (HATN), used as cathodes can exhibit excellent reversible Zn2+ storage capability with fast kinetics and the high capacity of 542 and 963 mA h g-1, respectively. The Zn//HMHATN and Zn//HATN full batteries display the high energy density of 160 and 221.6 W h kg-1, respectively, and long-term cycling stability. Further, we investigate the mechanism of Zn2+ storage in the cathodes. More importantly, the flexible aqueous Zn//HMHATN and Zn//HATN batteries fabricated also have high capacity, long-term cycling life and impressive energy density, displaying its application prospect in wearable electronics. Our work opens a new system for finding organic cathode materials used in aqueous zinc batteries.

Nitrogen-doped carbon/ZnO nanoparticles (ZnO-N-C) have been synthesized via an ordinary one-step calcination of a two-dimensional zinc-based coordination polymer [Zn(tfbdc)(4,4'-bpy)(H2O)(2)] (H(2)tfbdc=tetrafluoroterephthalic acid, 4,4'-bpy=4,4'-bipyridine). As an anode material for lithium-ion batteries, the obtained ZnO-N-C electrode exhibited high reversible capacity, excellent cyclic stability and better rate capability. The reversible capacity of the ZnO-N-C electrode maintains 611 mAh.g(-1) after 50 cycles at a current density of 50 mA.g(-1).

A new naphthalenediimide derivative, 2, 7-di (1, 2, 4-triazolyl) benzophenanthroline-tetraone (3-DTBPT) is synthesized by the condensation reaction of 1, 4, 5, 8-naphthalenetetracarboxylic anhydride (NTCDA) and 3-amino-1, 2, 4-triazole (3-AT). The 3-DTBPT material is characterized by Fourier transform infrared spectrum, X-ray diffraction, thermogravimetric analysis, solid state NMR spectra, field emission scanning electron microscopy, elemental analysis and Brunauer-Emmett-Teller surface. 3-DTBPT is insoluble in organic electrolyte. When used as a cathode material of lithium-ion batteries, 3-DTBPT exhibits an excellent cyclic stability, keeping a specific capacity of 110 mA h g(-1) and a nearly 94.8% capacity retention after 50 cycles at 50 mA g(-1). Our work provides an effective route for overcoming the dissolution problem of organic electrode materials and obtains a potential material for the long-cycle-life and flexible organic rechargeable batteries.

Ce-doped Bi 2 O 3 nanopowders were prepared by reverse titration chemical coprecipitation from Bi 3+ and Ce 4+ containing aqueous solution. Techniques of X-ray diffraction (XRD), transmission electron microscopic (TEM) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the as-synthesized materials. The XRD patterns indicated that the peaks can be easily indexed to β-Bi 2 O 3 and no diffraction peaks of Ce or other impurity phases were detected in the prepared samples. The calculated average crystalline size decreased from 31.72 to 11.96 nm when the Ce content increased from 1 wt% to 10 wt%. The morphology changed from flake-like into the spherical-like with increase in Ce content. The electric conductivity of Ce-doped Bi 2 O 3 electrolyte was also investigated by two probe DC method. Conductivity analysis exhibited that the rate of conductivity increased with increasing Ce 2+ ratio, when the Ce concentration was up to 5 wt%, the as-synthesized Ce-doped Bi 2 O 3 electrolyte showed the maximum value of conductivity(0.295 S·cm –1 ).

Monodispersed ZnO composite microspheres were successfully prepared by a facile ultrasound irradiation method. Then, the uniform core–shell structured composites were synthesized through the hydrolysis of tetraethyl orthosilicate on the surface of the ZnO composite microspheres. Microstructural studies of the as-obtained powders were carried out using the techniques of the x-ray powder diffraction, field emission scanning electron microscopy and transmission electron microscopy with energy dispersive x-ray spectroscopy. The results show that the pink ZnO composite powders as the core were spherical structures with the size of approximately 100 nm, and the SiO2 shell was fully coated on the surface of the core. On the basis of these results, the effect of SiO2 content on the thickness of the synthesized composites and microstructure, as well as the electrical properties of the ZnO varistors sintered in air at 1150°C for 2 h, were fully studied. In particular, the ZnO varistor prepared with the appropriate amount of the SiO2 coating (∼40 nm) leads to a superior electrical performance with the high breakdown voltage of 418 V mm−1 and an excellent nonlinear coefficient of 70.7, compared with the varistors obtained without the SiO2 coating. The high performance is attributed to the smaller and more homogeneous ZnO grains obtained via the SiO2 coating.

Carbon/sulfur composites were prepared by agradual carbonization method using sulfur, sucrose and diluted sulfuric acid as the reagents.SEM and TEM results showed that the as-prepared samples were evenly scatted spheres with core-shell structure in a diameter of about 3μm and the sulfur was loaded fully in these spheres.This kind of configuration offered an enhanced electrochemical performance with a discharge specific capacity of 1065 mAh/g.After 60 cycles, the discharge specific capacity faded slowly and tended to be stable with a discharge capacity of about 510 mAh/g and a fade rate of about 0.066％ after 150 cycles.The coulombic efficiency remained at above 90％ during long calendar cycles.These results indicated that the gradual carbonization method could be a suitable way to prepare the core-shell structured carbon/sulfur composite material for lithium-sulfur battery.

Naphthalenediimide diamine-functionalized graphene oxide exhibited a high specific capacity and good cyclic stability as a cathode material of lithium batteries.

以钛酸四正丁酯(TBOT)、氧化石墨烯、正硅酸四乙酯(TEOS)为原料,采用水热法合成了一系列二氧化钛(TiO2)/二氧化硅(SiO2)/石墨烯复合光催化剂,并对TiO2/SiO2/石墨烯复合光催化剂进行了表征.研究结果表明,随着SiO2用量的增大,TiO2/SiO2/石墨烯复合光催化剂的比表面积及气孔直径增大,在石墨烯用量为1％(wt,质量分数),SiO2用量为30％(摩尔百分数),10mg TiO2/SiO2/石墨烯复合光催化剂在80min内对亚甲基蓝(MB)溶液(10mg/L,40mL)的光催化降解率达到99.2％.