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Biomass‐derived carbon is a promising electrode material in energy storage devices. However, how to improve its low capacity and stability, and slow diffusion kinetics during lithium storage remains a challenge. In this research, we propose a "self‐assembly‐template" method to prepare B, N codoped porous carbon (BN‐C) with a nanosandwich structure and abundant pyridinic N‐B species. The nanosandwich structure can increase powder density and cycle stability by constructing a stable solid electrolyte interphase film, shortening the Li+ diffusion pathway, and accommodating volume expansion during repeated charging/discharging. The abundant pyridinic N‐B species can simultaneously promote the adsorption/desorption of Li+/PF6− and reduce the diffusion barrier. The BN‐C electrode showed a high lithium‐ion storage capacity of above 1140 mAh g−1 at 0.05 A g−1 and superior stability (96.5% retained after 2000 cycles). Moreover, owing to the synergistic effect of the nanosandwich structure and pyridinic N‐B species, the assembled symmetrical BN‐C//BN‐C full cell shows a high energy density of 234.7 W h kg−1, high power density of 39.38 kW kg−1, and excellent cycling stability, superior to most of the other cells reported in the literature. As the density functional theory simulation demonstrated, pyridinic N‐B shows enhanced adsorption activity for Li+ and PF6−, which promotes an increase in the capacity of the anode and cathode, respectively. Meanwhile, the relatively lower diffusion barrier of pyridinic N‐B promotes Li+ migration, resulting in good rate performance. Therefore, this study provides a new approach for the synergistic modulation of a nanostructure and an active site simultaneously to fabricate the carbon electrode material in energy storage devices. [ABSTRACT FROM AUTHOR]

Li-rich Mn-based materials provide higher capacity than commercial NCM layered materials due to the synergistic redox effect of cations and anions. However, lattice straining and structural collapse caused by the irreversible oxygen release at high voltage range during cycling, which results in severe capacity and voltage decay. Herein, a synergistic strategy of surface-induced spinel structure and F doping is provided to improve the structural stability. The surface spinel structure helps to reduce the structural collapse caused by electrolyte corrosion on the cathode and effectively inhibits voltage decay resulted from structural evolution. The stronger Mn-F bonds are formed by F doping to inhibit migration of transition metal (TM) and induce the uniform deposition of LiF to form the thinner and more stable CEI on the cathode. Accordingly, the designed cathode (LMNO-NF) shows remarkable cycling performance with the capacity retention of 86.68 ​% and voltage retention of 96.6 ​% for 200 cycles at 1C, higher than pristine material (68.76 ​% and 85.75 ​%). Therefore, this simple dual-modification strategy of one-step synthesis is promising for solving the structural evolution and voltage decay of Li-rich Mn-based cathode materials effectively, achieving further commercialization. [ABSTRACT FROM AUTHOR]

[Display omitted] The commercialization of lithium metal batteries (LMBs) is encountering significant challenges due to the electrolyte incompatibility and poor mechanical properties of polyolefin separators, as well as the hazardous growth of lithium dendrites at the anode. Simultaneously, the development of safe and environmentally-friendly separators has become a central focus in rechargeable battery technology. In this study, we introduce a novel Janus separator (CP@SiO 2), featuring a composite structure with cellulose paper (CP) as the base layer and electrospun polyvinylidene fluoride (PVDF) nanofibers as the top layer. The nanofibers are uniformly coated with mesoporous SiO 2 nanoparticles through hydrogen bonding. The CP@SiO 2 separator leverages its three-dimensional lithium-ion channels and rigid ceramic particles to enhance electrolyte retention and stabilize lithium metal anodes (LMA). Shielded by this separator, LMA exhibits an impressive cycling performance, enduring a current density of 2 mA cm−2 for 350 h without short-circuiting, effectively doubling the cycle life compared to conventional PP separators. Furthermore, the Li/LiFePO 4 cell utilizing the CP@SiO 2 separator demonstrates a high capacity of 101 mAh·g−1 at 5C, with 90 % capacity retention after 1000 cycles. This outstanding electrochemical performance is attributed to the compatible anode/separator interface and the effective inhibition of lithium dendrite growth. The research presented in this work capitalizes on a synergistic configuration design, offering a promising pathway towards the development of high-safety and advanced lithium-ion separators. [ABSTRACT FROM AUTHOR]

Polyaniline (PANi) has high theoretical specific capacitance by storing energy through redox reactions and thus is widely used in supercapacitors. However, the skeleton of PANi expands and contracts during the process of ion inhalation and exfoliation, which leads to a decrease in electrochemical performance. To solve this problem, we graft the sulfonic acid group onto the PANi backbone via a borate ester bond, which serves as a proton reservoir to provide protons for PANi to undergo redox reactions and provide pseudocapacitance. SPANi is then polymerized in situ on graphene oxide (GO), and its comprehensive performance of the electrode is further enhanced by designing ordered structures and synergistic interactions. The SPANi 5 /GO 5 composite that are created in-situ have a fantastic specific capacitance of 460.56 F g−1 at 1 A g−1 and maintained 85.19% of the primary capacitance after 10,000 cycles. The device is assembled with PAAM/H 2 SO 4 /GO as the gel electrolyte, which achieves a specific capacitance of 137.75 F g−1, and the capacitance is retains at 90.74% after 10,000 cycles. The supercapacitor exhibits a large energy density of 13.76 Wh kg−1 when the power density is 200.27 W kg−1. The present study presents a novel and efficient approach for the fabrication of high-performance supercapacitor electrodes. [Display omitted] • Grafting the sulfonic acid group onto the PANi backbone via borate ester bond. • The in-situ polymerization of SPANi on GO formed a composite electrode. • SPANi 5 /GO 5 composite electrode with specific capacitance up to 460.56 F g−1. • SPANi/GO as electrode and PAAM/H 2 SO 4 /GO as gel electrolyte form a supercapacitor. • The device has a capacitance retention rate of 90.74% after 10,000 cycles. [ABSTRACT FROM AUTHOR]

Abstract Biomass‐derived carbon is a promising electrode material in energy storage devices. However, how to improve its low capacity and stability, and slow diffusion kinetics during lithium storage remains a challenge. In this research, we propose a “self‐assembly‐template” method to prepare B, N codoped porous carbon (BN‐C) with a nanosandwich structure and abundant pyridinic N‐B species. The nanosandwich structure can increase powder density and cycle stability by constructing a stable solid electrolyte interphase film, shortening the Li+ diffusion pathway, and accommodating volume expansion during repeated charging/discharging. The abundant pyridinic N‐B species can simultaneously promote the adsorption/desorption of Li+/PF6− and reduce the diffusion barrier. The BN‐C electrode showed a high lithium‐ion storage capacity of above 1140 mAh g−1 at 0.05 A g−1 and superior stability (96.5% retained after 2000 cycles). Moreover, owing to the synergistic effect of the nanosandwich structure and pyridinic N‐B species, the assembled symmetrical BN‐C//BN‐C full cell shows a high energy density of 234.7 W h kg−1, high power density of 39.38 kW kg−1, and excellent cycling stability, superior to most of the other cells reported in the literature. As the density functional theory simulation demonstrated, pyridinic N‐B shows enhanced adsorption activity for Li+ and PF6−, which promotes an increase in the capacity of the anode and cathode, respectively. Meanwhile, the relatively lower diffusion barrier of pyridinic N‐B promotes Li+ migration, resulting in good rate performance. Therefore, this study provides a new approach for the synergistic modulation of a nanostructure and an active site simultaneously to fabricate the carbon electrode material in energy storage devices.

Sustainability and adaptability in structural design of the organic cathodes present promises for applications in alkali metal ion batteries. Nevertheless, a formidable challenge lies in their high solubility in organic electrolytes, particularly for small molecular materials, impeding cycling stability and high capacity. This study focuses on the design and synthesis of organic small molecules, the isomers of (E)‐5,5′‐difluoro‐[3,3′‐biindolinylidene]‐2,2′‐dione (EFID) and 3,9‐difluoro‐6,12‐dihydrodibenzo [c, h][2,6]naphthyridine‐5,11‐dione (FBND). While EFID, characterized by a less π‐conjugated structure, exhibits subpar cycling stability in lithium‐ion batteries (LIBs), intriguingly, another isomer, FBND, demonstrates exceptional capacity and cycling stability in LIBs. FBND delivers a remarkable capacity of 175 mAh g−1 at a current density of 0.05 A g−1 and maintains excellent cycling stability over 2000 cycles, retaining 90% of its initial capacity. Furthermore, an in‐depth examination of redox reactions and storage mechanisms of FBND are conducted. The potential of FBND is also explored as an anode in lithium‐ion batteries (LIBs) and as a cathode in sodium‐ion batteries (SIBs). The FBND framework, featuring extended π‐conjugated molecules with an imide structure compared to EFID, proves to be an excellent material template to develop advanced organic small molecular cathode materials for sustainable batteries. [ABSTRACT FROM AUTHOR]

Due to the synergistic effect between multiple elements, bimetallic selenides materials can generate more active sites in the electrochemical reaction process, which can significantly improve the electrical conductivity for anode materials. Nevertheless, it is liable to produce severe volume expansion and exhibit the poor electrochemical performance. Therefore, we decided to modify it by carbon cladding; the carbon-coated short rod-like NiCoSe2 (NiCoSe2@C) nanomaterials were synthesized through facile hydrothermal reaction, dopamine coating, and carbonization process. It was found that the as-prepared NiCoSe2@C nanomaterial exhibits stable structure, outstanding cycling stability, and high pseudocapacitive contribution. Specifically, the specific charging capacity is 370.6 mAh g−1 (0.1 A g−1, 100 cycles) and 304.8 mAh g−1 (2 A g−1, 600 cycles) as anode when used for SIBs. Comparing with the pure NiCoSe2 nanomaterial, the construction of carbon layer can mitigate the effect of volume expansion and reduce the generation of adverse materials, thus enhancing the cycling stability. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur batteries (LSBs) are one of the most promising and potential modern‐day energy storage devices due to the low‐cost sulfur‐based cathode and remarkably high energy density (∼2600 Wh kg−1). However, the detrimental shuttle effect of lithium polysulfide (LiPS) and the sluggish electrochemical redox kinetics of lithium sulfide (Li2S) formation restrict its commercial viability. Herein, we design a novel transition metal‐rare earth high entropy oxide (TM‐RE HEO) Co0.08Mn0.08Ni0.08Fe1.96Mg0.08Nd0.01Gd0.01Sm0.01Pr0.01O4 as a polysulfide adsorbent and catalyst for the redox reactions of sulfur species in Li−S battery. TM‐RE HEO interlayer exhibits an excellent discharge capacity of 1146 mAh g−1 at 0.1 C rate, high rate capability, and reasonable long‐term cycling stability at 0.5 C rate with a low capacity decay of 0.08 % per cycle after 300 cycles. High degree of chemical confinement of soluble polysulfides, as demonstrated by the strong bonding between TM‐RE HEO and Li2S6, and expedited catalytic conversion to insoluble Li2S, result from strong polar catalytically active multiple metal sites and abundant oxygen vacancies. This work demonstrates the potential of high entropy oxide in developing high‐efficiency LSB technology. [ABSTRACT FROM AUTHOR]

The growing demand for sodium-ion batteries (SIBs) in commercial applications has made it imperative to meet the commercial requirements. However, SIBs face significant challenges because of their poor cyclability and low reversible capacity compared with their rival lithium-ion batteries (LIBs). To address these challenges, various techniques, design strategies, surface engineering, and structural modifications have been developed to enhance the electrochemical performance of SIBs. This review focuses on recent developments in improving the electrochemical performance and cyclability of novel promising electrode materials for SIBs. We discuss several unique state-of-the-art research studies of the past five years that demonstrated excellent electrochemical performance through effective methodologies, surface modulations, and substitution of novel elements into the structure, and boosted the efficiency of the materials. Furthermore, we propose that it is important to adopt a nuanced approach when designing SIBs. Rather than copying the designs and methods used for LIBs, ideas should be absorbed from them and approaches should be tailored to meet the specific requirements of SIBs. This will enable the development of SIBs that are optimized for their intended applications and will avoid the challenges that have hindered the commercial success of earlier attempts at constructing SIBs. Thus, the key to creating high-performance SIBs is to draw inspiration from the best practices used in LIBs, while simultaneously innovating and developing new approaches tailored to the unique characteristics of SIBs.

Aqueous battery (AB) with non-metallic charging carriers is a viable candidate for grid energy storage devices owing to its comparatively low cost and high safety. However, developing practical electrode materials with remarkable electrochemical performance remains a great challenge. In this study, tungsten trioxide nanosheets (WONSs) with one-dimensional tunnels were facilely synthesized through a hydrothermal reaction. When used as the cathode material in aqueous batteries, the as-prepared WONS exhibits excellent long-term cycling stability and impressively high rate capability due to the nearly zero-strain structural characteristics of super-fast proton storage. Notably, a stable cycling performance with 89% capacity retention after 10000 cycles was achieved with an increased mass loading of WONS at around 12 mg cm−2. Our work points to a new direction of promoting high-efficiency AB applications with protons as charge carriers in a mild electrolyte.

The catalyst loading onto polymer films by pump-filtration can effectively solve the problem of catalyst separation and recycling, as well as expose more catalytically active sites. However, this method suffers from the disadvantage of poor catalyst attachment stability, which reduces the ability to catalyze the degradation of pollutants. In this paper, the high adhesion and film-forming properties of chitosan (CS) were utilized to modify the ZnO/NH 2 -MIL-88B (ZM) catalyst-loaded polypropylene non-woven (PP) composite membranes obtained by filtration, and CS/[ZM@PP] catalytic membranes with excellent catalyst adhesion stability and catalytic degradation performance were prepared. The results showed that the prepared CS/[ZM@PP]-X catalytic membranes significantly improved the recovery of the catalysts and possessed good catalytic performance, and the best-performed CS/[ZM@PP]-3 membrane could degrade more than 96.8 % of methylene blue (100 mL, 20 mg/L) within 60 min. In this paper, the effects of different factors on the catalyst recovery on the catalytic membrane were systematically investigated, and the prepared CS/[ZM@PP]-3 membrane can adapt to the complex aqueous environment, has excellent cycling stability, and still has more than 90 % degradation effect after 6 times of recycling, which has good potential for practical application. [Display omitted] • Preparation of catalytic membranes with high cycling stability. • Greatly improve the stability of catalyst adhesion in the membrane by filtration method. • Highly efficient removal of organic pollutants from water. [ABSTRACT FROM AUTHOR]

The development of flexible supercapacitors (SCs) with high energy density, excellent deformation and cycling stability has great meaning for flexible electronic. Herein, polyaniline array@carbon nanotubes/partially reduced graphene oxide hybrid fiber (PANI@CNT/PRGO) was rationally designed and fabricated. The PANI array were vertically and uniformly grown on CNT/PRGO fiber by controlling the nucleation sites on the fiber. This unique structure enabled the ion to rapid diffusion and the electron to fast transport and sufficient utilization of active sites. The strong interfacial interaction between PANI and CNT/PRGO fiber can reduce the risk of PANI shedding from the fiber during mechanical deformation and long-term cycling. As a consequence, a fiber-shaped SC fabricated by PANI@CNT/PRGO fiber can deliver high volumetric capacitance of 50.2 F cm−3 at a current density of 60 mA cm−3 with 62.5% capacitance retention at 2000 mA cm−3. More encouragingly, the device not only possesses outstanding flexibility and deformation stability (Retention 96.6% after 2000 bending cycles) but also owns prominent long-term stability (Retention 95.8% after 20,000 cycles). Furthermore, the device can yield an outstanding energy density up to 6.97 mWh cm−3. This findings may carve out a new path for regulating the nucleation sites to control the distribution of nanomaterials on graphene fiber, thus obtain hybrid fiber electrodes with outstanding electrochemical performances. [Display omitted] [ABSTRACT FROM AUTHOR]

Smart windows, which can provide comfortable indoor conditions for cars or buildings and protect the privacy of people, have attracted much attention. Traditional acrylate‐based smart windows have the disadvantages of high energy consumption and poor stability. Herein, an energy‐efficient smart window based on a liquid crystalline composite stabilized by an epoxy polymer with boscage‐like morphology is reported. This epoxy polymer is prepared by cationic polymerization of the liquid crystalline epoxy monomer E6M in vertically oriented negative nematic liquid crystals. The orientation of the liquid crystals is controlled by the epoxy polymer, which makes the composite film transparent and switchable to scattering by an electric field. Therefore, the composite film can be used in an energy‐efficient reverse‐mode smart window. The reverse‐mode smart window has better cycling stability than does acrylate, owing to the better mechanical properties endowed by the polymer matrix with a unique morphology and high stress tolerance. [ABSTRACT FROM AUTHOR]

[Display omitted] • SPANi is synthesized by copolymerization of aniline and 2-aminobenzenesulfonic acid. • In-situ polymerization of SPANi on MXene to form composite electrode. • SPANi 3 /MXene 3 composite electrode with specific capacitance up to 512.45 F g−1. • The double crosslinked organogel electrolyte with anti-freezing property is prepared. • The capacitance retention rates of the device are 81.82 % (−40 °C) after 10,000 cycles. Polyaniline (PANi) is widely used in supercapacitors owing to its unique structural flexibility and redox behavior. However, due to the limitations of the inherent molecular structure, the expansion and contraction of the PANi skeleton will be triggered during the charging and discharging process, leading to decreased stability and rapid degradation. For this reason, we design a novel sulfonated polyaniline structure of aniline copolymerized with 2-aminobenzenesulfonic acid, thus immobilizing the sulfonic acid group (−SO 3 H) side chain onto the PANi main chain. The −SO 3 H acts as a proton reservoir to provide protons for PANi, accelerating the occurrence of redox reactions and providing pseudocapacitance, effectively suppressing the deprotonation phenomenon. Then SPANi is grown in-situ on the interlayers of MXene, which induces the disordered polymer to be ordered on the MXene substrate, forming a 3D interconnected network composite with both high specific capacitance and excellent stability. SPANi/MXene composite has an outstanding specific capacitance of 512.45 F g−1 at 1 A/g and retains up to 92.16 % of the initial capacitance after 10,000 cycles. Assembled with PHEAA-PAA-MXene double-crosslinked organogel electrolyte to form an anti-freezing device with a specific capacitance of 158.63 F g−1, it retains a high specific capacitance of 118.26 F g−1 even under the extreme conditions of −40 °C. The capacitance retention after 10,000 cycles is 95.2 % (20 °C) and 81.82 % (−40 °C), respectively. This work provides simple and effective methods to fabricate high-performance PANi-based electrodes and anti-freezing supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract Herein, N-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying method. In the preparation process, HCl-treated melamine (HTM) is selected as the sources of carbon and nitrogen. It not only realizes in situ growth of CNTs on the surface of MXene nanosheets with the catalysis of Ni, but also introduces efficient N-doping in both MXene and CNTs. Within the microsphere, MXene nanosheets interconnect with CNTs to form porous and conductive network. In addition, N-doped MXene and CNTs can provide strong chemical immobilization for polysulfides and effectively entrap them within the porous microspheres. Above-mentioned merits enable N-Ti3C2@CNT microspheres to be ideal sulfur host. When used in lithium–sulfur (Li–S) battery, the N-Ti3C2@CNT microspheres/S cathode delivers initial specific capacity of 927 mAh g−1 at 1 C and retains high capacity of 775 mAh g−1 after 1000 cycles with extremely low fading rate (FR) of 0.016% per cycle. Furthermore, the cathode still shows high cycling stability at high C-rate of 4 C (capacity of 647 mAh g−1 after 650 cycles, FR 0.027%) and high sulfur loading of 3 and 6 mg cm−2 for Li–S batteries.

Abstract Organic cathode materials are promising candidates for a new generation of ‘green batteries’, since they have low toxicity and can be produced from renewable resources or from petroleum. This review shows that organic redox polymers can show excellent battery performance regarding cycling stability and rate capability, and attractive specific capacities are accessible. Radical polymers and redox polymers based on heteroaromatics demonstrate superior rate capabilities and cycling stabilities at fast C-rates as well as high discharge potentials of 3–4 V versus Li/Li+, while quinone- or imide-based polymers deliver high specific capacities of up to 260 mAh g−1 with stable cycling at moderate C-rates and lower discharge potentials. This review article highlights the underlying design principles showcasing selected examples of well-performing redox polymers.

TiO 2 is exceptionally useful anode material for Li-ion batteries, and the ability to modify TiO 2 makes it a very attractive and challenging research object for use in different functional materials. In this paper, mesoporous TiO 2 nano hollow spheres (dubbed TiO 2 -1 andTiO 2 -2) with moderate oxygen vacancies were successfully prepared. Structure and composition characterizations revealed that the spheres had a hollow structure, surface oxygen vacancies and an excellent Ti3+/Ti4+ molar ratio of 0.181. In addition, TiO 2 -2 demonstrated synergistic effects in terms of electron and lithium ion transportation, with impedances as low as 3.05 Ω, and its Li-ion diffusion coefficient (7.8 × 10−12 cm2 s−1) was at least a factor of 10 larger than that of TiO 2 -1(6.2 × 10−13 cm2 s−1). More importantly, experiments demonstrated that the well-balanced Li+/e− transportation arising from the synergetic effect between structure and Ti3+/oxygen vacancy in the optimal TiO 2 -2 sample had a high specific capacity of 233 mAh·g−1 at 0.1C, and 79.8% capacity retention after 100 cycles, as well as greatly enhanced rate performance and electrochemical reactivity and stability in comparison with the other TiO 2. Our method for creating oxygen vacancies in TiO 2 nano hollow spheres can be generalized to other electrochemical energy storage materials. [ABSTRACT FROM AUTHOR]

Li7La3Zr2O12 (LLZO) with cubic phase structure is a kind of lithium-ion-conducting nanoparticles. According to the previous studies, incorporation of c-LLZO can improve electrochemical properties of PEO-based composite polymer electrolytes (CPEs). Therefore, in our study, we synthesized a kind of room-temperature-stable cubic phase LLZAO (Li6.25La3Zr2Al0.25O12) nanofibers, and we aimed to confirm the optimal content of LLZAO nanofibers in PEO-based CPEs. With the incorporating 10 wt% LLZAO nanofibers, ionic conductivity of CPEs are 9.87×10−5 S cm−1 at 30 °C and 8.66×10−4 S cm−1 at 60 °C. The Li/CPE incorporating 10 wt% LLZAO nanofibers/Li symmetric cell exhibits little voltage fluctuation in 1000 cycles under a current density of 0.5 mA cm−2, demonstrating better cycling stability with long cycle life. The LiFePO4/CPE incorporating 10 wt% LLZAO nanofibers/Li cell has a high initial discharge-specific capacity of 155.6 mAh g−1 under 0.1 C rate at 60 °C and remains 94.5% of capacity after 100 cycles. This cell also has great cycling performance under 0.2 C and 0.5 C rate, indicating good rate performance. Our work indicates that incorporation of LLZAO nanofibers enhances electrochemical properties and cycling stability of PEO-based all-solid-state lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Herein, KH-550 was used as surface modifier to prepare modified MnO2/reduced graphene oxide (M-MnO2/rGO) composite electrode materials by utilizing electrostatic interaction at low temperature and normal pressure. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy were adopted to characterize the material's phase, morphology, and valence state of elements. The electrochemical properties of the material were measured using a three-electrode system. The results indicate a decrease in the size of the modified MnO2 particles, and that they were uniformly distributed on the rGO sheets. The M-MnO2/rGO composite attained a specific capacitance of 326 F ⋅ g − 1 in a solution of 1 mol ⋅ L − 1 Na2SO4 at a current density of 0.5 A ⋅ g − 1 . The specific capacitance of the material was 92.4% after 1000 cycles. The electrostatic self-assembly method effectively solved the problem of reducing the cycling stability while improving the specific capacitance of the composite materials, and further improved the possibility of applying MnO2/rGO in the field of supercapacitors. M-MnO2/rGO electrode materials with higher specific capacitance and improved cycle life were prepared through KH-550 modification. The reaction stability of MnO2 in aqueous solution was improved and the dispersity of MnO2 particles in the composite was solved by graft modification. In addition, the asymmetric supercapacitor achieves the maximum energy density of 36.4 Wh·kg–1 with the power density of 212.5 W·kg–1, showing intriguing application prospect. [ABSTRACT FROM AUTHOR]

The development of low-cost and highly active bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great significance to promote the practical application of Zn-air battery (ZAB). Herein, the authors report a facile strategy for the fabrication of Fe7S8 nanoparticles embedded in the N, S co-doped porous carbon (NSC) network that served as an efficient bifunctional catalyst. The obtained Fe7S8/NSC shows remarkable oxygen electrocatalytic activity, in terms of superior ORR activity to commercial Pt/C as well as comparable OER capability to RuO2. Besides, when evaluated as the cathode catalyst for a homemade ZAB, Fe7S8/NSC also displays a superior peak power density of 135 mA cm−2 and high cycling stability over 65 h (195 cycles). [ABSTRACT FROM AUTHOR]

Metallic selenides are considered as a promising class of alternative anodes for sodium ion batteries due to the high capacity conferred by their hybrid sodium storage mechanism. However, the low reversible volume expansion induced by larger size sodium ion storage greatly limits their cycle life, theoretical capacity mining and electrode thickness enhancement. Herein, a germanium selenide/carbon nanofibers (GeSe/CNFs) sodium storage anode is first reported by taking advantage of the encapsulation and dispersion of electrostatic spinning technology, i.e., GeO 2 is first mixed with polyacrylonitrile and electrospun to form a wrapped structure, followed by in situ pre-oxidation, carbonization, and selenization. For the optimized electrode, it delivers a high capacity up to 567 mAh g−1 based on the mass of GeSe (320 mAh g−1 based on GeSe/CNFs), reaching > 80% of its theoretical capacity, with a > 2300 cycles cycling stability at 1.0 A g−1. In addition, its capacity barely decays after 700 cycles at near commercial electrode thickness (115 µm, the capacity retention > 47–63% even at the ultrahigh thickness of 187–219 µm). This study opens up new possibilities for the development of Se-based sodium storage anode materials with long life, high capacity and ultra-thick electrode that are expected to meet practical needs. [Display omitted] • GeSe has been reported for the first time as a novel sodium storage material. • Homogeneous dispersion of GeSe in carbon fibers (CNFs) imparts high capacity. • CNFs wrapped GeSe effectively suppresses the instability caused by swelling. • The pore network of CNFs facilitates the smooth diffusion of ions. • It promotes to manufacture ultra-thick electrodes suitable for commercial use. [ABSTRACT FROM AUTHOR]

As one of representative conducting polymers (CPs), poly(3,4-ethylenedioxythiophene) (PEDOT) possesses fascinating electrochromic properties and commercial applications, but it suffers from the poor cycling stability in the charge-discharge process. In this work, we adopted a dual-approach mode to prepare high-quality PEDOT film in boron trifluoride etherate (BFEE) system via reducing the initial oxidation potential (E onset) of 3,4-ethylenedioxythiophene (EDOT) monomers to increasing the conjugation degree of PEDOT films and no requiring the addition of other supporting electrolytes to protect the initial structure of PEDOT films. The E onset of EDOT monomers in BFEE system was only 0.5 V, which was much smaller than other systems reported (1.00–1.26 V). The obtained PEDOT film with porous structure showed remarkable stability with an electrochemical activity retention rate of 91.5% after 190,000 cycles, and that of its electrochromic device (ECD) was 94.23% after 41,000 s. During the redox process, ECD had three color transformations (brown red, cyan, and blue) and the oxidation time and the reduction time were 0.4 s and 1.2 s, respectively. The calculated CE value reached 120 cm2 C−1. All these results suggest that the dual-approach mode can significantly enhance the quality of PEDOT film and thus enhance its cycling stability. In addition to that, the dual-approach mode can provide an effective strategy for the design of highly stable CPs for fabricating long-term stable ECD. [Display omitted] • A dual-approach mode was proposed to prepare high-quality PEDOT film. • BFEE increased the conjugation degree of PEDOT films by decreasing the initial oxidation potential. • BFEE system could protecting the initial structure of PEDOT films requiring no additional supporting electrolytes. • PEDOT film showed remarkable stability with an electrochemical activity retention rate of 91.5% after 190,000 cycles. • The transmittance of ECD based on PEDOT film remained 92.75% after 41,000 s. [ABSTRACT FROM AUTHOR]

Highlights: N-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying and one-step pyrolysis. Within the microsphere, MXene nanosheets intimately interact with CNTs constructing porous and highly conductive network, which can provide strong immobilization for polysulfides. N-Ti3C2@CNT microsphere/S cathode shows highly cycling stability in lithium-sulfur battery. Herein, N-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying method. In the preparation process, HCl-treated melamine (HTM) is selected as the sources of carbon and nitrogen. It not only realizes in situ growth of CNTs on the surface of MXene nanosheets with the catalysis of Ni, but also introduces efficient N-doping in both MXene and CNTs. Within the microsphere, MXene nanosheets interconnect with CNTs to form porous and conductive network. In addition, N-doped MXene and CNTs can provide strong chemical immobilization for polysulfides and effectively entrap them within the porous microspheres. Above-mentioned merits enable N-Ti3C2@CNT microspheres to be ideal sulfur host. When used in lithium–sulfur (Li–S) battery, the N-Ti3C2@CNT microspheres/S cathode delivers initial specific capacity of 927 mAh g−1 at 1 C and retains high capacity of 775 mAh g−1 after 1000 cycles with extremely low fading rate (FR) of 0.016% per cycle. Furthermore, the cathode still shows high cycling stability at high C-rate of 4 C (capacity of 647 mAh g−1 after 650 cycles, FR 0.027%) and high sulfur loading of 3 and 6 mg cm−2 for Li–S batteries. [ABSTRACT FROM AUTHOR]

A facile approach that combines the chemical etching with sulfidation of the sacrificial templates of the Fe-based MOFs is developed to prepare FeS 2 @ Porous Octahedral Carbon (FeS 2 @POC). The porous carbon shell can improve the conductivity of active materials, bring a high reversible capacity. Moreover, the void space between carbon and FeS 2 can accommodate the volume changes during cycling and the existence of carbon can prevent the aggregation of pulverized FeS 2 particles during Li ions insertion/extraction process, which are favorable to gain superior cycling stability. When used as an anode for lithium-ion batteries, the FeS 2 @POC shows superior electrochemical performance with a high specific capacity, excellent rate performance (381 mAh g−1 at 5000 mA g−1) and good cyclability (1074 mAh g−1 at 100 mA g−1 after 100 cycles, about 99% capacity retention). The results demonstrate that this product may be considered as a promising anode material for advanced lithium-ion batteries. [ABSTRACT FROM AUTHOR]

• Supercapacitor performance of CuO/ZnSb 2 O 6 nanocomposites was explored. • CuO/ZnSb 2 O 6 nanocomposites delivered better electrochemical stability. • The electrochemical stability is due to non-aggregation effect. • The non-aggregation effect is due to ultrasonic-assisted preparation methodology. • CuO/ZnSb 2 O 6 nanocomposites could be potential supercapacitor electrode materials. In this work, a new nanohybrid consisting of copper oxide and zinc antimonate was designed using ultrasonication assisted homogenous magnetic stirring approach and investigated their performance as an electrode material for supercapacitors. Combination of the duo could enhance the electrical conductivity and charge storage capacity of whole nanostructured electrode, which is very much essential for supercapacitor application. Primarily, the prepared nanohybrid electrode material was investigated through XRD, FT-IR, FE-SEM, HR-TEM, UV-DRS, PL and XPS to determine their structural, morphological, optical and compositional characteristics. Thereafter, the electrochemical properties of the nanohybrid electrode were investigated using CV, GCD and EIS studies in 1.0 M KOH solution. The fabricated nanohybrid electrode material exhibits exceptional electrochemical performance by delivering maximum specific capacitance of 257.14 F g−1 at a current density of 12.5 A g−1. The nanocomposite showed high cycling stability of 102.0% even after 2000 cycles at a current density of 10.0 A g−1. These exceptional electrochemical characteristics of CuO/ZnSb 2 O 6 nanocomposites are due to their dual nanorod morphology, influence of ultrasonication on non-aggregated nanocomposite formation, presence of more number of electrochemical active sites, and their synergistic interactions. The obtained results confirmed that CuO/ZnSb 2 O 6 nanocomposites could be a potential candidate as electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]

Highlights • CoS@rGO@C are introduced as anode for sodium-ion batteries. • Specific capacity of porous CoS@rGO@C after 100 cycles is 567 mAh·g−1. • Extra outer carbon coating leads to enhanced cycling stability. Abstract Carbon-coated cobalt sulfide@reduced graphene oxide (CoS@rGO@C) composite was innovatively synthesized by a simple solvothermal reaction and subsequent carbon coating process for use as the anode material in sodium-ion batteries (SIBs). In this composite structure, the rGO network and extra outer carbon coating worked synergically to achieve excellent electrode architecture stability upon long-term cycling. Specifically, the CoS@rGO@C composite anode demonstrated superior reversible capacity (706 mAh·g−1 at 100 mA·g−1 at the 1st cycle), high rate capability (374 mAh·g−1 at 1.6 A·g−1), and remarkably stable cycling performance (80% capacity preservation for up to 100 cycles) based on the synergistic action of rGO and carbon coating on CoS. In addition to improving the electrochemical performance of CoS anodes, this composite material strategy can be conveniently adapted to other metal-based anode designs to improve their cycling stability and promote their application in energy storage. [ABSTRACT FROM AUTHOR]

Abstract SnO x is considered as a promising anode candidate for lithium-ion batteries, but suffers from the low electrical conductivity and severe volume expansion during cycling. To solve these issues, we develop a simple and facile process of incipient wetness impregnation followed by pyrolysis gel molecules to prepare SnO x /mesoporous carbon nanofiber arrays, SnO x /graphene, SnO x /carbon nanotubes and SnO x /three-dimensionally ordered macroporous carbon materials. Notably, SnO x nanoparticles about 5 nm are prepared by a nonaqueous sol-gel method. We also explore the effect of different morphologies and pore structures of four carbon substrates on the electrochemical performance of the composites. Benefiting from the small size of SnO x nanoparticles and the synergistic effect between SnO x and the different carbon matrix materials, SnO x -Carbon electrode materials display excellent rate capability and cycle stability. SnO x /mesoporous carbon nanofiber arrays exhibits the best rate (522 mA h g−1 at 2000 mA g−1) and cycling performances (1327 mA h g−1 after 200 cycles at 100 mA g−1). The superior electrochemical performance, facile synthesized method and low cost of the Sn-based materials exhibit promising application for SnO x /mesoporous carbon nanofiber arrays as anode materials for next-generation lithium-ion batteries. Furthermore, the ex situ X-ray photoelectron spectroscopy studies on this electrode material under different states suggest that the Sn and Li 2 O could reversibly react to form SnO x during the charging process. [ABSTRACT FROM AUTHOR]

Zn 3 V 2 O 8 (ZVO) with sheet-like morphology is synthesized by a simple green precipitation technique via a metal-organic framework (MOF) intermediate for use as an anode in high energy lithium-ion batteries (LIBs). This sheet-like morphology, enriched with highly porous features, is evident from transmission electron microscopy (TEM) and surface area measurements. When tested as a lithium half-cell electrode, the ZVO porous sheets delivered a reversible specific capacity of 1228 mA h g −1 at a current density of 0.3 A g −1 for 200 cycles. Interestingly, on applying two different high current densities of 1 and 3 A g −1 , this porous ZVO material registered high capacities of 665 and 510 mA h g −1 , initially for 30 and 50 cycles, respectively. On reducing the current density to 0.5 and 1 A g −1 for the two instances, both sustained stable capacities of 906 and 687 mA h g −1 in the 160th and 600th cycles, respectively. The fact that these porous sheets maintained a stable capacity as high as 370 mA h g −1 at the high applied current density of 5 A g −1 after 2000 discharge/charge cycles reveals the structural stability of the ZVO prepared by a simple green precipitation technique. [ABSTRACT FROM AUTHOR]

We report the preparation of a series of LiNi 0.8 Co 0.15 Al 0.05 O 2 materials with different reaction time (10, 20, 30 and 40 h) of precursor and their electrochemical properties as cathode material for lithium-ion batteries (LIBs). The preparation of LiNi 0.8 Co 0.15 Al 0.05 O 2 was divided into two steps: a co-precipitation process to obtain Ni 0.8 Co 0.15 Al 0.05 (OH) 2 precursor and a calcination step with LiOH. During the co-precipitation process, AlO 2 - was employed as Al source so as to guarantee Ni 2+ , Co 2+ and Al 3+ co-precipitation. The impacts of different synthesis time of the precursor on crystal structure, morphology and electrochemical performance of LiNi 0.8 Co 0.15 Al 0.05 O 2 were systematically investigated. The samples with various synthesis time of precursor possessed spherical morphology and a layered α-NaFeO 2 structure with R-3m space group. Especially, when the reaction time of precursor was 30 h, the LiNi 0.8 Co 0.15 Al 0.05 O 2 had the weakest degree of Li + /Ni 2+ ions mixing and the best uniformity and integrity. When used as cathode materials for LIBs, the LiNi 0.8 Co 0.15 Al 0.05 O 2 with 30 h exhibited high discharge capacity, good cycling performance and remarkable rate capability. The maximum discharge capacity was 202.3 mAh g −1 at 0.1 C and the capacity retention approached 99.4% after 100 cycles at 1 C. At 10 C, the discharge capacity exceeded 140 mAh g −1 , suggesting a possible application in the high rate LIBs. The excellent electrochemical performance might be attributed to the uniform co-precipitation of Ni 2+ , Co 2+ and Al 3+ and well layered structure with less Li + /Ni 2+ mixing. [ABSTRACT FROM AUTHOR]

We reported a polyacrylic acid/polyacrylamide-based hydrogel electrolyte containing gelatin for efficient electrochromic device with outstanding cycling stability and flexible compatibility. [Display omitted] • A polyacrylic acid/polyacrylamide-based hydrogel electrolyte containing gelatin was developed for electrochromic devices. • The present electrochromic device showed high optical contrast over 85 %. • The present electrochromic device exhibited outstanding stability with less than 3 % loss of the initial optical contrast after 15,000 cycles switching. • The efficient adhesiveness of the present hydrogel electrolyte enabled the compatibility with flexible device and improved the device bending stability. Hydrogel electrolytes have been attracted intense research interest due to their widespread applications in advanced electronic devices. In this work, we developed a new hydrogel electrolyte to overcome two critical issues in electrochromic devices, involving long-term cycling stability and flexible compatibility. Briefly, gelatin was introduced into a hydrogel polymer matrix based on polyacrylic acid/polyacrylamide, resulting in high transparency, high electronic conductivity, durable electrochemical stability, inherent adhesiveness. Complementary electrochromic devices employing the present hydrogel electrolyte exhibited efficient performance with high optical contrast over 85 %, short response time, high coloration efficiency of 205.7 cm2/C. Remarkably, an excellent operation stability was achieved with less than 3 % loss of the initial optical contrast after 15,000 cycles switching, which was the best case among those based on the same electrochromic materials reported so far. Moreover, the efficient adhesiveness of the present hydrogel electrolyte enabled the compatibility with flexible device and improved the device bending stability. These findings might shed light on the development of durable and flexible electrochromic devices toward practical application. [ABSTRACT FROM AUTHOR]

Ternary graphene/sulfur/SiO 2 (graphene/S/SiO 2 ) composite has been successfully synthesized by compositing sulfur with graphene and then wrapping with SiO 2 . The graphene/S/SiO 2 composite exhibits superior specific capacity and improved cycling stability owing to the combined contributions from both graphene and SiO 2 when used as cathode materials for lithium/sulfur batteries. The graphene/S/SiO 2 demonstrates a specific capacity of 696 mAh g −1 after activated, which is considerably higher than the graphene/S and pure sulfur samples. In addition, the graphene/S/SiO 2 and graphene/S composites demonstrate improved cycling stability and much higher coulombic efficiency than the pure sulfur sample owing to the successful prevention of polysulfides diffusion. Furthermore, both graphene/S/SiO 2 and graphene/S composites show an activation step in first 30 cycles, which can be attributed to the gradually increased capacity from reduction of high-order polysulfides to low-order polysulfides. [ABSTRACT FROM AUTHOR]

Poly(ethylene oxide)-coated sulfur/carbon (S/C/PEO) composite with a high sulfur loading is prepared to improve the performance of lithium-sulfur batteries. By magnetic string, 3.7 wt% PEO is coated onto the surface of ball-milling obtained S/C composite, leading to synthesis of S/C/PEO composite containing 78 wt% S. It is confirmed from a series of measurements that PEO covers the S/C composite uniformly, and PEO coating is quite effective in stabilizing the electrochemical performance. When employed as cathode for lithium-sulfur batteries, S/C/PEO delivers an initial discharge capacity of 989.6 mAh g and remains 648.3 mAh g after 110 cycles at a discharge/charge rate of 1 C (based on sulfur weight). Meanwhile, the coulomb efficiency of S/C/PEO composite reaches to ~98 % during the latter 105 cycles. The improved electrochemical performance can be attributed to the formation of PEO coating layer which can keep a tight contact between carbon and sulfur and lead to improved conductivity. Moreover, the PEO coating can act as a flexible cushion to accommodate volume changes of sulfur cathode as well as a barrier to trap soluble polysulfide intermediates during the charge-discharge processes. [ABSTRACT FROM AUTHOR]

Ternary graphene/sulfur/polyaniline (graphene/S/PANI) composites have been successfully prepared via a facile two-step synthesis method. S nanoparticle is uniformly decorated on the graphene surface, and PANI nanowires cover the graphene/S surface. When used as cathode material for lithium-sulfur batteries, the specific ternary composite achieves excellent electrochemical performance with high capacity and improved cycling stability. The graphene/S/PANI sample delivers a specific capacity of up to 837 mAh g −1 after a few cycles at 0.1C, which is considerably higher than that delivered by the graphene/S sample. In addition, the graphene/S/PANI sample and the graphene/S sample show improved cycling stability with improved Coulombic efficiency compared with pure S sample. This observation indicates the successful prevention of the polysulfide species diffusion owing to graphene introduction. Furthermore, the activation mechanism of graphene/S is studied through morphology change during cycling, which demonstrates that activation is ascribed to the gradual spread of S on the graphene surface during cycling. [ABSTRACT FROM AUTHOR]

An utrastable and excellent organic cathode of DNPT/rGO has been developed for aqueous zinc-ion batteries (ZIBs), with good capacity of 120 mAh g−1 after 1000 cycles. Product of DNPT 2 (H+) 6 (Zn2+) from two adjacent DNPT molecules with one zinc ion and six protons by DFT is optimal structure during charging-discharging, which provides a broad prospective of carbonyl compounds used for ZIBs. [Display omitted] • Organic carbonyl compound of DNPT/rGO is proposed for aqueous zinc-ion battery. • DNPT/rGO aqueous zinc-ion battery delivers outstanding cycle life over 2000 cycles. • Co-participate of proton and zinc ion mechanism verified by Ex-situ and CV analysis. • DNPT 2 (H+) 6 (Zn2+) is optimal structure during charge/discharge by DFT calculation. Carbonyl compounds have been widely used for cathodes of aqueous zinc-ion batteries (ZIBs) nowadays, however, poor electrical conductivity has limited its development. Reduced graphene oxide (rGO) could easily interact with carbonyl compounds by π-π stacking to achieve good conductivity. Herein, a carbonyl compound, 6,15-dihydrodinaphtho[2,3- a :2′,3′- h ]phenazine-5,9,14,18-tetraone (DNPT, pigment blue 60), interacts with rGO to obtain DNPT/rGO as cathode for ZIBs, which shows excellent stability with capacity of 120 mAh g−1 after 1000 cycles at current density of 500 mA g−1, as well as good rate performance (20C). Through ex-situ analysis and density functional theory calculation, synergistic mechanism of proton and zinc ion in DNPT/rGO has been detailed discussed with three possible discharging processes of DNPT(H+) 4 , DNPT 2 (H+) 6 (Zn2+), DNPT 2 (H+) 4 (Zn2+) 2. The combination of two adjacent DNPT molecules with one zinc ion and six protons suggests optimal structure of DNPT 2 (H+) 6 (Zn2+) during charge–discharge process. Prospectively, DNPT/rGO material with good electrical performance and high cycling stability would inspire development of carbonyl compounds used for ZIBs. [ABSTRACT FROM AUTHOR]

The heterostructured cathode material has been successfully constructed with Nb-based MXenes, which exhibits excellent structural stability and electrochemical performance. [Display omitted] • LMR/Nb-based MXenes heterostructured Li-rich cathode material is successfully constructed. • Spinel phase and oxygen vacancies are formed due to Nb-based MXenes introduction. • Pseudo-bonding between Nb and O ions can be induced by Nb-based MXenes decoration. • The electrochemical performance was greatly improved for the heterostructured cathode. Lithium rich manganese based materials (LMR) have promised the likeliest candidate for next generation lithium-ion battery cathodes owing to its high energy density and low materials cost. However, severe capacity decline and voltage decay hinder their practical application, which is closely concerned with the structure degradation and irreversible oxygen release. Herein, a simple strategy to reinforce the structural stability of LMR materials by constructing heterostructure with Nb-based MXenes (Nb 2 CT x / Nb 4 C 3 T x) is proposed. A small amount of spinel phase and pseudo-bonding between Nb and O ions as well as extra oxygen vacancies can be induced by the MXenes addition in LMR, effectively inactivating the surface oxygen and suppressing the structure distortion. In addition, MXene can also alleviate the volume change during cycling process and provide additional transport channels for electrons. The ably designed 3 wt% LMR/Nb 2 CT x cathode presented high initial Coulombic efficiency of 85.6% at 0.1C (vs. 77.4% for the pristine material) and excellent cycling performance with a capacity retention of 83.8% after 200 cycles at 0.5C (vs. 66.6% for the pristine material). This work sheds some light on stabilizing the structure of lithium-rich manganese materials and provides a new idea for the design of other high performance cathode materials. [ABSTRACT FROM AUTHOR]

Hybrid supercapacitors are considered the next-generation energy storage equipment due to their superior performance. In hybrid supercapacitors, battery electrodes need to have large absolute capacities while displaying high cycling stability. However, enhancing areal capacity via decreasing the size of electrode materials results in reductions in cycling stability. To balance the capacity-stability trade-off, rationally designed proper electrode structures are in urgent need and still of great challenge. Here we report a high-capacity and high cycling stability electrode material by developing a nickel phosphate lamination structure with ultrathin nanosheets as building blocks. The nickel phosphate lamination electrode material exhibits a large specific capacity of 473.9 C g -1 (131.6 mAh g -1 , 1053 F g -1 ) at 2.0 A g -1 and only about 21% capacity loss at 15 A g -1 (375 C g -1 , 104.2 mAh g -1 , 833.3 F g -1 ) in 6.0 M KOH. Furthermore, hybrid supercapacitors are constructed with nickel phosphate lamination and activated carbon (AC), possessing high energy density (42.1 Wh kg -1 at 160 W kg -1 ) as well as long cycle life (almost 100% capacity retention after 1000 cycles and 94% retention after 8000 cycles). The electrochemical performance of the nickel phosphate lamination structure not only is commensurate with the nanostructure or ultrathin materials carefully designed in supercapacitors but also has a longer cycling lifespan than them. The encouraging results show the great potential of this material for energy storage device applications.

In order to enhance the electrochemical activity of transition metal chalcogenide anodes for sodium ion batteries (SIBs), anion-doping and carbon modification are demonstrated to be effective methods. In this work, using polydopamine (PDA) coated metal organic framework of MIL-88-Fe (MIL-88-Fe/PDA) as self-template, N-doped Fe 7 S 8 embedded in N-doped carbon (N–Fe 7 S 8 @NC) are successfully fabricated, through a high-temperature sulfurization process. Benefited from the PDA coating, integral peapod-liked nanoarchitecture can be preserved, and N atoms are doped both in the Fe 7 S 8 lattice and the carbon matrix and shell. This stable peapod-liked N–Fe 7 S 8 @NC nanoarchitecture with continuous carbon protection, shows fast Na+ insertion/extraction reaction kinetics, demonstrating as fast and stable anode material for SIBs. It displays highly stable capacities of 312.7 mAh g−1 at 5.0 A g−1 after 2000 cycles, giving a capacity retention of 98.1%. Even at ultrahigh current of 10.0 A g−1, after long-term cycling (4000 cycles), a capacity of 238.4 mAh g−1 can be maintained, giving an impressive capacity retention of 81.5%. For the possible kinetics mechanism, the ultrafast pseudocapacitive contribution and higher adsorption energy induced by the anion-doping, may promote its high-rate sodium storage capability. [Display omitted] • Nitrogen-doped Fe 7 S 8 coated by nitrogen-doped carbon shell (N–Fe 7 S 8 @NC) was designed. • N-doping in the Fe 7 S 8 can induce extrinsic defects and modulated band structure. • N–Fe 7 S 8 @NC shows fast Na+ reaction kinetics and good cycling stability. • Capacitive contribution promotes the high rate performance for sodium storage. [ABSTRACT FROM AUTHOR]

• A covalent grafting interface engineering strategy to prepare PP-g-mSiO 2 separator. • The covalent bonding force increase the interfacial stability of the separator. • The mSiO 2 facilitates more storage of electrolyte and swift lithium-ion diffusion. • The LiFePO 4 cell exhibits excellent rate capability and cycling stability. Due to the deficiency of low melting point and poor wettability of commercial polyolefin separators, the design and development of ceramic coating separators have been received more and more attention in Li-ion batteries recently. However, it is challenging to solve the disadvantageous exfoliation issue of ceramic coating during charge/discharge cycles and needs to be addressed urgently. Herein, a covalent grafting interface engineering strategy has been proposed to prepare a highly efficient and stable polypropylene/mSiO 2 separator (PP-g-mSiO 2) by the nanoscale mSiO 2 layer anchoring on the surface of PP separator with covalent bonding. As expected, the covalent bonding force increase the interfacial stability of PP-g-mSiO 2 separator and the mSiO 2 NPs facilitate more storage of electrolyte, which results in high thermal stability, high electrolyte affinity and swift lithium-ion diffusion. When used as the separator in LIBs, the Li/LiFePO 4 cell with PP-g-mSiO 2 separator exhibits excellent rate capability with a discharge capacity of 101 mA h/g at 5 C and remains high capacity retention of 93% after 1000 continuous charge–discharge cycles, which suggests that the PP-g-mSiO 2 separator possesses a stable and covalent grafting ceramic surface and have greater affinity to electrolyte, resulting in quicker lithium-ion diffusion and excellent cycling stability. Therefore, the covalent grafting interface modification has confirmed an effective strategy to block exfoliation issues of ceramic coating and developed the high-performance ceramic separators for LIBs. [ABSTRACT FROM AUTHOR]

• A facile, controllable and scalable method is used to prepare CNF@MnO 2 nanowires. • Synergistic effect of CNF@MnO 2 ensures the enhanced capacity and rate capability. • An ultra-stable cyclability is achieved at a wide range of current density (0.2–3 A g−1). • CNF@MnO 2 holds substantial promise for cost-effective, large-scale and stable ZIBs. Aqueous Zn/MnO 2 batteries have attracted considerable attention for large-scale energy storage application owing to their low cost, high safety and environmental friendliness. However, MnO 2 cathodes still suffer from the inferior utilization and deficient cyclability at a wide range of current densities. Integrating MnO 2 with conductive carbon is promising to overcome the challenges. Unfortunately, the required use of strongly oxidative acids or expensive plasma to functionalize the inherently hydrophobic carbon makes it an obstacle for scalable production. Herein, the hierarchical core-shell carbon nanofiber(CNF)@MnO 2 (MOC) nanowires were synthesized by using a facile, controllable and scalable approach combining simple grinding and low-temperature wet-chemical reaction. A synergistic effect was demonstrated for the MOC cathode in Zn-ion batteries (ZIBs). The conductive CNF backbone significantly boosts the electron transfer kinetics, while ultrathin MnO 2 nanosheets provide large electrode/electrolyte interfacial contact areas and facilitate the ionic diffusion. Additionally, the intimate contact between CNFs and MnO 2 synergistically renders an interconnected network with high electronic and ionic conductivity and flexibility to minimize structural collapse and strain of volume variation upon cycling. The favorable synergistic effect ensures the high capacity, long shelf life, enhanced rate capability and extraordinary cycling stability of MOC. It shows a high capacity of 221 mAh g−1 after 700 cycles at 200 mA g−1. Even at 3000 mA g−1, it still maintains 130 mAh g−1 after 2750 cycles without obvious capacity decay. Featuring the exceptional electrochemical performance, rational design for synergy and low-cost manufacturing, the developed MOC cathode is promising for cost-efficient and high-performance ZIBs. [ABSTRACT FROM AUTHOR]

Silicon-based anode for lithium-ion batteries (LIBs) has attracted much attention due to its high theoretical capacity, low operating potential and abundant resources. However, the large volume expansion/shrink during the lithiation/delithiation process induces extreme damage to the electrode microstructure. The resulting failure of electrical contact between silicon and current collector will severely deteriorate the cycling stability. Herein, a three-dimensional nano-Si/N-doped carbon network was obtained by a facile approach with NaCl templates. The N-doped carbon network not only significantly improves the electronic conductivity, but also ensures a valid electrode microstructure through a highly elastic carbon framework. Additionally, a two-dimensional nano-Si/N-doped carbon sheet was prepared without NaCl templates, revealing the boosting action of NaCl templates in the microstructure adjustment from low dimension to spatial crosslinking. The optimal three-dimensional nano-Si/N-doped carbon composite can deliver a high specific capacity of 1396 mAh g−1 with a capacity retention of 84.3% after 100 cycles at 200 mA g−1. This study provides effective guidance for novel Si-based anode design to achieve high-energy LIBs with excellent cycling stability. Image 1 [ABSTRACT FROM AUTHOR]

Highlights: N-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying and one-step pyrolysis. Within the microsphere, MXene nanosheets intimately interact with CNTs constructing porous and highly conductive network, which can provide strong immobilization for polysulfides. N-Ti3C2@CNT microsphere/S cathode shows highly cycling stability in lithium-sulfur battery. Herein, N-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying method. In the preparation process, HCl-treated melamine (HTM) is selected as the sources of carbon and nitrogen. It not only realizes in situ growth of CNTs on the surface of MXene nanosheets with the catalysis of Ni, but also introduces efficient N-doping in both MXene and CNTs. Within the microsphere, MXene nanosheets interconnect with CNTs to form porous and conductive network. In addition, N-doped MXene and CNTs can provide strong chemical immobilization for polysulfides and effectively entrap them within the porous microspheres. Above-mentioned merits enable N-Ti3C2@CNT microspheres to be ideal sulfur host. When used in lithium–sulfur (Li–S) battery, the N-Ti3C2@CNT microspheres/S cathode delivers initial specific capacity of 927 mAh g−1 at 1 C and retains high capacity of 775 mAh g−1 after 1000 cycles with extremely low fading rate (FR) of 0.016% per cycle. Furthermore, the cathode still shows high cycling stability at high C-rate of 4 C (capacity of 647 mAh g−1 after 650 cycles, FR 0.027%) and high sulfur loading of 3 and 6 mg cm−2 for Li–S batteries. [ABSTRACT FROM AUTHOR]

Both poor electron conductivity and low ion diffusion of electrode materials are two main issues limiting the rate performance of pseudocapacitors. The present work reports the design and fabrication of hierarchically nano-architectured electrodes consisting of sulfide vacancies enhanced Ni-Co-S nanoparticle covering bent nickel nano-forest (BNNF). We propose new insight into vastly increased ion-accessible active sites and fast charge storage/delivery enhanced the reaction kinetics. The Ni-Co-S@BNNF electrode exhibits extremely high rate performance with 90.1% capacity retention from 1 to 20 A g -1 , and even still remains 83.6% capacity at 40 A g -1 , much superior to reported NiCo 2 S 4 -based electrodes. The high rate performance is attributed to the unique nano-architecture providing increased ion availability of electrochemically active sites and high conductivity for fast electron transport. Especially the electrode achieves remarkable long-term cycle stability with more than 100% initial capacity value after 5000 cycles at 5 A g -1 and exhibits excellent cycle reversibility even at 20 A g -1 . Goog cycle stability should be attributed to the sulfide vacancies in Ni-Co-S nano-branches and the electrode architecture sustaining structural strain during fast redox reactions. An asymmetric pseudocapacitor applying such electrode achieves a high energy density of 99.9 W h kg -1 and exhibits superior cycling stability at a high current density of 20 A g -1 . This study underscores the potential importance of developing nanoarrays covered with highly redox-active materials with increasing ions/charge kinetics for energy storage., (© 2021 IOP Publishing Ltd.)

• A universal strategy for multi-shelled hollow microsphere of transition metal oxides. • Homogeneous and monodispersed Co/Ni-MOF was designed. • The Co 3 O 4 @C electrode show high capacity and excellent cycling performance for LIBs. • The proposed synthesis strategy demonstrated great potentials in materials science. Although the synthesis of transition metal oxide hollow structure is well established, it is still very difficult to control the size distribution, morphological uniformity, cavity volume, shell clarity and functional groups of products. Herein, the strategy of "oxidation-sedimentation-recrystallization-formation" was proposed to synthesis of well-defined multi-shelled hollow microsphere by thermal oxidation of the metal-organic frameworks (MOFs) general precursors. The spherical Ni-MOF and Co-MOF are first synthesized and subsequently transformed into corresponding multi-shelled metal oxide and carbon composites. These nitrogen-doped multi-shelled Co 3 O 4 @carbon hollow microspheres were adopted as anode for lithium-ion batteries, demonstrating remarkable electrochemical properties. Impressively, an ultra-high reversible capacity of 1701 mAh g−1 was retained at a current density of 100 mA g−1 after 60 cycles. Even at a large current density of 5000 mA g−1, 427 mAh g−1 was retained. [ABSTRACT FROM AUTHOR]

Cu–MOF was obtained by a facile aqueous room temperature synthesis method, and Cu–C was prepared by using Cu–MOF as a sacrificial template. The ultrafine SnOx nanoparticles were loaded onto Cu–C by a pyrolysis process to form SnOx/Cu–C. Cyclic voltammetry and galvanostatic charge/discharge were employed to examine the electrochemical properties of the as-synthesized composite. Benefiting from the excellent conductivity of Cu, the ultra-fine size of nanoparticles, the unique structure derived from MOF and the synergistic effect between SnO X and Cu–C, SnO X /Cu–C electrode exhibited an exceptional electrochemical property. A high charge specific capacity of 649 mA h g−1 can be reached even at a current density of 2000 mAg−1. The reversible capacity is maintained at 668 mA h g−1 at 1000 mA g−1 after 300 cycles. The results indicate that the material may be considered as a promising anode candidate for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Herein, high‐content N‐doped carbon nanotube (CNT) microspheres (HNCMs) are successfully synthesized through simple spray drying and one‐step pyrolysis. HNCM possesses a hierarchically porous architecture and high‐content N‐doping. In particular, HNCM800 (HNCM pyrolyzed at 800 °C) shows high nitrogen content of 12.43 at%. The porous structure derived from well‐interconnected CNTs not only offers a highly conductive network and blocks diffusion of soluble lithium polysulfides (LiPSs) in physical adsorption, but also allows sufficient sulfur infiltration. The incorporation of N‐rich CNTs provides strong chemical immobilization for LiPSs. As a sulfur host for lithium–sulfur batteries, good rate capability and high cycling stability is achieved for HNCM/S cathodes. Particularly, the HNCM800/S cathode delivers a high capacity of 804 mA h g−1 at 0.5 C after 1000 cycles corresponding to low fading rate (FR) of only 0.011% per cycle. Remarkably, the cathode with high sulfur loading of 6 mg cm−2 still maintains high cyclic stability (capacity of 555 mA h g−1 after 1000 cycles, FR 0.038%). Additionally, CNT/Co3O4 microspheres are obtained by the oxidation of CNTs/Co in the air. The as‐prepared CNT/Co3O4 microspheres are employed as an anode for lithium‐ion batteries and present excellent cycling performance. [ABSTRACT FROM AUTHOR]