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A ternary core–shell metal-free supercapacitor composed of a CS/CN/PPy nanocomposite material was successfully fabricated via a CVD method and an in situ polymerization route.

Unexpected strongly luminescent complexes were constructed via the weakly luminescent [1]rotaxane coordinating with Zn2+ specifically due to the coordination-induced emission effect.

The multiple ordered porous honeycomb structure of g-C3N4 with carbon ring in-plane splicing (Cr–PHCN) has been successfully fabricated with simultaneous morphology regulation and electronic structure modulation.

CuNiSxQDs were fabricated onto g-C3N4by photochemical deposition method. The small size can expose more active S sites on the edge and the introduction of Cu2+into NiSxcan slightly modulate the electronic structure of Ni and S centers, thus weakening the S–Hadsbonds.

Alkaline aqueous batteries such as the Zn||Ni batteries have attracted substantial interests due to their merits of high energy density, high safety and low cost. However, the freeze of aqueous electrolyte and the poor cycling stability in alkaline condition have hindered their operation in subzero conditions. Herein, we construct a stable aqueous electrolyte with lowest freezing point down to -90 °C by adding dimethyl sulfoxide (DMSO) as alkaline tolerant antifreezing additive into 1 M KOH solution. Meanwhile, we find the DMSO can also retard Zn anode corrosion and prevent Zn dendrite formation in alkaline condition, which enables the Zn plating/stripping over 700 h cycle at 1 mA cm

The renaissance of aqueous Zn ion batteries has drawn intense attention to Zn metal anode issues, including dendrites growth, dead Zn, low efficiency, and other parasitic reactions. However, against the widely used 2D Zn foil, in fact, the Zn powder anode is a more practical choice for Zn-based batteries in industrial applications, but the related solutions are rarely investigated. Herein, we focus on the Zn powder anode and disclose its unknown failure mechanism different from Zn foils. By utilization of 2D flexible conductive Ti3C2Tx MXene flakes with hexagonal close-packed lattice as electrons and ions redistributor, a stable and highly reversible Zn powder anode without dendrite growth and low polarization is constructed. Low lattice mismatch (∼10%) enables a coherent heterogeneous interface between the (0002) plane of deposited Zn and (0002) plane of the Ti3C2Tx MXene. Thus, the Zn2+ ions are induced to undergo rapid uniform nucleation and sustained reversible stripping/plating with low energy barriers via the internally bridged shuttle channels. Paired with cyano group iron hexacyanoferrate (FeHCF) cathode, the FeHCF//MXene@Zn full battery delivers superior cycle durability and rate capability, whose service life with a CE of near 100% touches 850% of bare Zn powder counterparts. The proposed Ti3C2Tx MXene redistributor strategy concerning high-speed electrons/ions channel, low-barrier heterogeneous interface, is expected to be widely applied to other alkali metal anodes.

The Zn metal anodes of aqueous zinc ion batteries (ZIBs) suffer from dendrites and severe side reactions, such as the hydrogen evolution reaction (HER) and passivation, which seriously restrict the shelf life of ZIBs. Herein, these issues were addressed with a solid polymer electrolyte (SPE) based on the poly(vinylidene fluoride-co-hexafluoropropylene) filled by the poly(methyl acrylate) grafted MXenes (denoted as PVHF/MXene-g-PMA) for the first time. Homogeneously dispersed MXenes were achieved benefiting from the intriguing interaction between the highly grafted PMA and PVHF matrix. The resulting SPE exhibits three orders of magnitude larger ionic conductivity than the PVHF matrix, reaching 2.69 × 10−4 S cm−1 at room temperature. Dendrite-free Zn plating/stripping with high reversibility was achieved (over 1000 h cycles at room temperature and 200 h at high temperature). Subsequently, the fabricated solid full cells with eliminated HER and suppressed anode dendrites exhibited excellent cycling performance of 10 000 cycles at 2C at room temperature and could work normally at temperatures ranging from −35 °C to 100 °C. Most importantly, over 90 days of shelf life was attained for the all-solid-state ZIBs after storage at low/high temperatures. Our work represents a substantial progress on the all-solid-state ZIBs with superior stability and reliability, reflected by the effectively suppressed dendrites and side reactions, excellent cycling performance and remarkable shelf life.

Proposed are Prussian blue analogue hosts with ordered and continuous channels, and electrocatalytic functionality with open Co and Fe species, which facilitate maximum I2 utilization efficiency and direct I2 to I- conversion kinetics of the I2 reduction reaction, and free up 1/3 I- from I3 - . Co[Co1/4 Fe3/4 (CN)6 ] exhibits a low energy barrier (0.47 kJ mol-1 ) and low Tafel slope (76.74 mV dec-1 ). Accordingly, the Co[Co1/4 Fe3/4 (CN)6 ]/I2 //Zn battery delivers a capacity of 236.8 mAh g-1 at 0.1 A g-1 and a rate performance with 151.4 mAh g-1 achieved even at 20 A g-1 . The battery delivers both high energy density and high-power density of 305.5 Wh kg-1 and 109.1 kW kg-1 , higher than I2 //Zn batteries reported to date. Furthermore, solid-state flexible batteries were constructed. A 100 mAh high capacity solid-state I2 //Zn battery is demonstrated with excellent cycling performance of 81.2 % capacity retained after 400 cycles.

Rechargeable Mg-ion battery is regarded as a promising candidate for grid-scale energy storage due to the intriguing features of Mg, including high volumetric capacity, enhanced safety and abundance. However, solid-state Mg-ion full batteries have been rarely reported originating from the limited availability of electrodes and electrolytes. Here, we, developed a solid-sate Mg hybrid ion full battery consisting of an cobalt hexacyanoferrate cathode, an organic 3,4,9,10-perylenetetracarboxylic diimide anode and a solid polymer electrolyte of poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) film filled with polyethylene oxide (PEO)/ionic liquid-based magnesium salt electrolyte (ILMSE). The solid-sate batteries can operate well at high rate of 3A⋅g−1 with a high capacity of 75 mAh•g−1 and superior cyclic stability of 95.9% after 5000 cycles at 2 A⋅g−1. More interestingly, the solid-state battery can withstand a high temperature up to 120 °C, a low temperature down to -20 °C, as well as sewing test of 180 times, demonstrating excellent temperature adaptability and superior sewability. This is the first demonstration of a solid-state Mg ion battery with high excellent electrochemical performance, flexibility and environmental adaption, which could pave the way for practical application of Mg-ion batteries for grid-scale energy storage and flexible/wearable application.

Electrolyte solutions and electrode active materials, as core components of energy storage devices, have a great impact on the overall performance. Currently, supercapacitors suffer from the drawbacks of low energy density and poor cyclic stability in typical alkaline aqueous electrolytes. Herein, the ultrathin Co

Nonbattery behavior related phase transition of electrodes is usually not favorable for any batteries because it results in performance degradation at all times. Here, we demonstrate a zinc hybrid-...

The consensus practice in research of high energy density energy storage devices is to simultaneously achieve high areal capacity and high intrinsic specific capacity. Increasing the areal capacity of batteries necessitates the maximization of their mass loading. However, batteries usually deliver mass loading-dependent electrochemical performance. Take selenium (Se) cathode with a theoretically high specific capacity as an example, Se reaction kinetics, utilization and cycling lifespan seriously deteriorate with increased Se mass loading. Here, we propose an electrocatalytic Se reduction/oxidation reaction strategy to realize high-Se-loading Zn||Se batteries with fast kinetics and high Se utilization. Specifically, the synergetic effects of Cu and Co transition-metal species inside channel structure of host can effectively immobilize and catalytically convert Sen during cycling, which thus facilitates Se utilization and 6-electron (Se4+ \(\leftrightarrow\) Se2–) conversion kinetics. In particular, the Cu[Co(CN)6] host exhibits a remarkably low energy barrier (1.63 kJ·mol−1) and low Tafel slope (95.23 mV·dec−1) for the Se reduction, and highest current response for Se oxidation. Accordingly, the Zn battery employing Se-in-Cu[Co(CN)6] cathode delivers a capacity of 664.7 mAh⋅g−1 at 0.2 A⋅g−1, an excellent rate capability with 430.6 mAh⋅g−1 achieved even at 10 A⋅g−1, and long-cyclic life over 6000 cycles with 90.6% capacity retention. Furthermore, an A-h-level (~1350 mAh) Zn||Se pouch-type battery with high Se loading (~12.3 mg(Se)⋅cm−2) shows a high Se utilization of 3.3 % and outstanding cyclic stability with 9.4 % initial capacity retained after 400 cycles at exceedin 98 % Coulombic efficiency.

One of the most important methods for modifying semiconductors is defect engineering, but only the right quantity of defects in the right chemical environment can produce desirable results. Heat treatment processes associated with g-C3N4 are occasionally carried out in N2 atmosphere, however, the catalytic performance of g-C3N4 produced by direct condensation of only nitrogen-rich precursors in N2 atmosphere is often unsatisfactory. This is typically attributed to the introduction of numerous defects, but the actual relationship between the formation of defects and the N2 atmosphere is rarely explained, and the resulting quantity of defects is difficult to control. We propose that the melam to melem transition is restricted due to the lack of O2 during the heat treatment of the nitrogen-rich precursor of g-C3N4 in N2 atmosphere, which leads to a substantial quantity of defects in the synthesized g-C3N4. To enhance its photocatalytic property, we propose a method to reduce the quantity of defects due to calcinating in N2 atmosphere by protonating the precursor in a way that increases the polymerization of the product. The test analysis indicated that only a moderate quantity of defects that contribute to electron excitation and enhance the separation efficiency and density of photogenerated carriers were retained, and the hydrogen evolution performance of the prepared catalyst was significantly improved.

With the growing demands for large-scale energy storage, Zn-ion batteries (ZIBs) with distinct advantages, including resource abundance, low-cost, high-safety, and acceptable energy density, are considered as potential substitutes for Li-ion batteries. Although numerous efforts are devoted to design and develop high performance cathodes and aqueous electrolytes for ZIBs, many challenges, such as hydrogen evolution reaction, water evaporation, and liquid leakage, have greatly hindered the development of aqueous ZIBs. Developing "beyond aqueous" electrolytes can be able to avoid these issues due to the absence of water, which are beneficial for the achieving of highly efficient ZIBs. In this review, the recent development of the "beyond aqueous" electrolytes, including conventional organic electrolytes, ionic liquid, all-solid-state, quasi-solid-state electrolytes, and deep eutectic electrolytes are presented. The critical issues and the corresponding strategies of the designing of "beyond aqueous" electrolytes for ZIBs are also summarized.

The renaissance of aqueous Zn ion batteries has drawn intense attention to Zn metal anode issues, including dendrites growth, dead Zn, low efficiency, and other parasitic reactions. However, against the widely used 2D Zn foil, in fact, the Zn powder anode is a more practical choice for Zn-based batteries in industrial applications, but the related solutions are rarely investigated. Herein, we focus on the Zn powder anode and disclose its unknown failure mechanism different from Zn foils. By utilization of 2D flexible conductive Ti

Practical application of flexible energy storage devices has not been realized despite the booming of experimental researches. One major concern is their poor mechanical durability, which has seldom been investigated in literatures. On one hand, their flexibility is not good enough to accommodate arbitrary deformations, which was merely demonstrated by statically bending at certain angles. Thus, stability against dynamic mechanical stimuli is highly desired. On the other hand, these devices are not strong enough to endure severe mechanical stimuli including large shear forces and impacts, which greatly limits their practicability. Therefore, device-level toughness to ensure long-term usability is also needed. Here, a mechanically durable Zn-MnO2 battery is developed based on a dual-crosslinked hydrogel electrolyte without the usage of separator. Due to the effective energy dissipation of the hydrogel, the as-fabricated battery maintains a stable energy output when being dynamically deformed under severe mechanical stimuli. It can be vastly deformed into various shapes without electrochemical performance decay, showing excellent flexibility. It also exhibits super toughness that can endure two days' treading pressure and survive 20 times of random run-over by cars on road. These demonstrations reveal its outstanding mechanical stability and durability, suggesting great potential in truly flexible and wearable applications.

Featuring with low cost, exceptional inherent safety and decent electrochemical performance, rechargeable Zn-based batteries (RZBs) have attracted increased attention and revived research efforts recently as a compelling alternative battery chemistry to Li-ion. However, some challenges still stand in the way of the development of these energy storage systems, such as low operation voltage, instability of cathode materials as well as dissolution of Zn electrode, etc. In this review, we present a comprehensive overview of recent progress in different RZBs systems including mild electrolyte RZBs, alkaline RZBs, hybrid RZBs, Zn-ion capacitors and Zn air batteries. The fundamental chemistry of various RZB systems, different cathode materials, optimization of Zn anode as well as various types of electrolytes and their influence on the battery performance are summarized. The major issues of different components along with respective strategies to alleviate them are discussed, aiming at providing a general guide for design and construction of high-performance RZBs. Additionally, the development of RZBs with different features in the last few years are summarized. Finally, we discuss the limitations and challenges that need to be overcome, providing potential future research directions in the field of next-generation RZBs.

Flexible Zn-air battery (ZAB) depicts promising prospects for the eventual realization of next-generation flexible electronic devices. However, developing such flexible power sources with high efficiency and durability remains a great challenge, largely due to the low effectiveness of the key components within the ZAB configuration. Herein, we demonstrate an efficient, flexible and rechargeable ZAB by integrating an active Co-N-C reversible electrocatalyst and a highly conductive alkalined polyacrylate hydrogel. The active sites for the oxygen reduction and evolution reactions (ORR-OER) within the catalyst are carefully identified and facily tuned, enabling the engineered catalyst to deliver much better bifunctional activities than the noble-metal counterparts yet with only approximately 7% cost of the latter. The alkalined hydrogel affords preeminent ionic conductivity and water retention capability, well satisfies the role for solid-state electrolyte. Impressively, the thus fabricated solid-state flexible ZAB exhibits an open circuit voltage of 1.45 V, a peak power density of 144.6 mW cm−2, a round trip efficiency of 62%, a stable rechargebility for over 400 cycles at 2 mA cm−2 along with excellent flexibility, which even outperform those from many aqueous ZABs, highlighting its great potential as flexible power source for next-generation electronics.

3D porous boron nitride (BN) foam with thin boron nitride nanosheets walls has been prepared by a in situ templet-free foaming reaction with ammonia borane and thiourea. Thiourea serves as foaming agent in the synthesis and frothing the precursor into Three-dimensional (3D) structure BN foam with thin walls. The products are hierarchically porous with large area of rough surfaces, presenting high adsorption of N2/CO2. Typically, for CO2 adsorption, it could reach up to 150 ml/g under 50 bar at room temperature.

Recently, rechargeable Zn-ion batteries (ZIBs) have attracted incremental attention as prospective energy storage devices for grid-scale applications and flexible devices, due to their low cost, environmental benignity, high safety and unique properties of the Zn metal. However, the sustained development of high-performance ZIBs is hindered by the limited availability of cathode materials. Here, for the first time, we demonstrate MoS2 with expanded inter-layer spacing (E-MoS2) can be a promising cathode candidate for rechargeable and flexible ZIBs. By X-ray diffraction (XRD) and Raman studies, a reversible Zn2+ ion intercalation/deintercalation mechanism was revealed. The E-MoS2 electrode delivers a specific capacity of 202.6 mA h g−1 at 0.1 A g−1, a desirable energy density of 148.2 Wh kg−1 and good cycle stability with a capacity retention ratio of 98.6% over 600 cycles. By using the newly-developed starch/ polyacrylamide (PAM) based polymer electrolyte with high zinc ion conductivity, a quasi-solid Zn/E-MoS2 battery was developed, which exhibits decent electrochemical performance even under various heavy deformations, holding great potential for applications in future flexible and wearable devices.

Nanoscale transition metal oxides and polyoxometalates attract great attention due to their short diffusion channel distance and reversible redox reaction. However, the inevitable agglomeration, shrinkage and volumetric expansion/shrinkage of nanomaterials seriously affect their electrochemical properties. Here, the 3D heterostructure CoWO4/Co3O4 nanocone arrays are synthesized via a facile and efficient microwave hydrothermal method. The obtained CoWO4/Co3O4 NCAs overcome these shortcomings and achieve high electrochemical performance. The electrochemical behaviors of as-prepared composites are investigated systematically, during which four pairs of redox peaks in cyclic voltammetry curve are observed and discussed in detail. The kinetic analysis of redox reaction is employed to confirm the redox pseudocapacitance mechanism (surface capacitance-dominated process) and intercalation pseudocapacitance mechanism (diffusion-controlled process) of charge storage, suggesting faradaic intercalation process of 3D heterostructure CoWO4/Co3O4 NCAs (22% diffusion contribution at 0.8 mV s−1). The assembled solid-state hybrid supercapacitors further exhibit high energy density (45.6 Wh kg−1) and power density (7500 W kg−1 at 32.8 Wh kg−1) even at a super-high total loading mass of 23.1 mg of active materials. This work provides some meaningful and significant basis and foundation for the study of supercapacitors.

Three challenges remain unsettled for current flexible energy storage devices. One is that most developed devices are not soft enough to conform various deformations; another is that they can hardly guarantee a stable energy output when being dynamically deformed―most of the ever-reported tests on flexibility are performed under static conditions; the third is that they lack sufficient toughness at device level, meaning they are vulnerable to severe mechanical stresses. We believe these problems must be well settled before wearable devices can be practically applied. Here we report a hydrogel with excellent energy-dissipating ability that can be simultaneously used as high-performance electrolyte, super-tough separator and highly effective electrode protector for supercapacitors. The developed supercapacitor is highly soft and super tough at device level. It can well maintain its stable output when being dynamically bent and exhibits high resistance to severe mechanical stimuli including blade-cut, hammering, etc. It can be arbitrarily deformed into irregular shapes while keeping original performances. Moreover, it can even survive extremely harsh conditions including 6 days’ treading and 50 times of car run-over without notable deterioration in capacitance and long-term stability. This super tough supercapacitor shows great potential in truly wearable applications involving severe mechanical stresses and impacts.

Safety and brilliant electrochemical performance are the most important elements for advanced battery systems. Aqueous Zn batteries are considered a promising technology to meet the safety requirements, but are limited by their inferior electrochemical properties. Combining with zinc–air batteries is an effective way to improve the energy density of Zn batteries by introducing the oxygen evolution reaction and the oxygen reduction reaction into the whole electrochemical process. Hence, Ni3S2 nanosheets were utilized as a novel cathode for both Zn batteries and hybrid Zn–air–metal batteries (ZAMBs), of which the energy storage mechanisms were clearly demonstrated. The hybrid ZAMBs exhibited an evident two-stage charge and discharge process and displayed highly stable discharge platforms of 1.7 V and 1.1 V, and could work for more than 300 hours, uninterruptedly. More importantly, sodium polyacrylate served as the separator for the flexible hybrid Zn battery prototype, which shows superior electrochemical properties in an alkaline environment to other hydrogel membranes. This work could introduce a novel method to greatly improve the energy density of Zn batteries and further promote the development of hybrid Zn battery systems.

Aqueous rechargeable zinc ion batteries with advantages of low cost and high level of safety have been considered as a promising candidate for large-scale energy storage. In this work, a freestanding, binder-free cathode comprising hierarchical VS2 in the 1T phase grown directly on a stainless steel mesh (VS2@SS) was developed for aqueous zinc ion batteries. The battery exhibited an excellent Zn ion storage capacity of 198 mA h g−1 and stable cycling performance (above 80% capacity retention over 2000 cycles at 2 A g−1). The detailed structural and chemical composition analyses revealed the phase evolution of VS2 and the reversible Zn ion insertion/extraction mechanism during the charge/discharge process. Notably, with an increased mass loading of VS2 over the commercial level (∼11 mg cm−2), a long-term cycling stability with 90% capacity retention after 600 cycles (only 0.017% loss per cycle) could be achieved, which suggests that the electrodes are promising for practical applications. Furthermore, flexible solid-state Zn ion batteries were demonstrated by using the VS2@SS electrodes, and reliable electrochemical performance could be observed even after 200 cycles.

High electrochemical performance energy storage devices coupled with low cost and high safety operation are in urgent need due to the increasing demand for flexible and wearable electronics. For these applications lithium-ion and sodium-ion batteries are vastly limited due to their relatively low power density and security risks. On the other hand, conventional supercapacitors are suitable for flexible and wearable electronics due to their high power density while their low energy density has hindered their wide applications. Lithium or sodium ion hybrid supercapacitors are promising energy storage devices that benefit from the combined high energy density of batteries and high power density of supercapacitors. However, the use of organic electrolytes and shortage of lithium resources are expected to limit their widespread commercialization for flexible and wearable electronics. Here, for the first time, we introduce a safe and flexible solid-state zinc ion hybrid supercapacitor (ZHS) based on co-polymer derived hollow carbon spheres (HCSs) as the cathode, polyacrylamide (PAM) hydrogel as the electrolyte and Zn deposited on carbon cloth as the anode. Owing to the high surface area of the HCSs and the hollow structure which improves the ion adsorption and desorption kinetics of the cathode, the flexible solid-state ZHS delivers a highest capacity of 86.8 mA h g−1 and a maximum energy density of 59.7 W h kg−1 with a power density of 447.8 W kg−1. Besides, it displays excellent cycling stability with 98% capacity retention over 15 000 cycles at a current density of 1.0 A g−1. Moreover, the solid-state ZHS is flexible enough to sustain various deformations including squeezing, twisting and folding due to the use of flexible electrodes and electrolytes. Our study unveils a pioneering flexible solid-state ZHS with high safety, which is a promising candidate for flexible and wearable energy storage devices.

Recently, non-invasive detection and diagnosis technology of electrical equipment has developed rapidly. Pulse current method with PDcheck is one of the common methods to detect the partial discharge of electrical appliances. However, the PDcheck device not only detects the expected defect discharge, but also other types of discharge, especially the discharge of insulating bushing. And few efforts have been made to identify these two types of discharges. The purpose of this paper is to distinguish them with a simple and easy method. An experimental platform is designed, which is relatively easy to discharge. Then the needle plate defect on the disc insulator is set as artificial defect, and the defect is placed in the sealing chamber. The discharge threshold voltage of the defect can be controlled by adjusting the proportion of N 2 and SF 6 in the environment. Two types of discharge can be identified by analyzing PRPD spectrum and time-frequency relationship. However, it is found that PDcheck results with different defects do not have superposition, which conflicts with previous experimental results. A possible explanation is put forward, i.e. when the intensity of partial discharge in the casing is close to or greater than the intensity of partial discharge in the defect, the partial discharge in the casing will produce electromagnetic interference to the defect. A more accurate explanation of this phenomenon needs further study.

Aqueous graphite-based dual ion batteries have unique superiorities in stationary energy storage systems due to their non-transition metal configuration and safety properties. However, there is an absence of thorough study of the interactions between anions and water molecules and between anions and electrode materials, which is essential to achieve high output voltage. Here we reveal the four-stage intercalation process and energy conversion in a graphite cathode of anions with different configurations. The difference between the intercalation energy and hydration energy of bis(trifluoromethane)sulfonimide makes the best use of the electrochemical stability window of its electrolyte and delivers a high intercalation potential, while BF4− and CF3SO3− do not exhibit a satisfactory potential because the graphite intercalation potential of BF4− is inferior and the graphite intercalation potential of CF3SO3− exceeds the voltage window of its electrolyte. An aqueous dual ion battery based on the intercalation behaviors of bis(trifluoromethane)sulfonimide anions into a graphite cathode exhibits a high voltage of 2.2 V together with a specific energy of 242.74 Wh kg−1. This work provides clear guidance for the voltage plateau manipulation of anion intercalation into two-dimensional materials., The interactions between water molecules, electrode materials and anions are essential yet challenging for aqueous dual ion batteries. Here, the authors demonstrate the voltage manipulation of dual ion batteries through matching intercalation energy and solvation energy of different anions.

Zn metal batteries are promising for large-scale energy storage systems because of their extremely intrinsic safety and low cost. However, parasitic side reactions such as hydrogen evolution, Zn corrosion, and flourished dendrite growth behavior impede their practical implementation. Notably, electrode/electrolyte interface plays a critical role in regulating Zn deposition and improving the cyclic lifespan of rechargeable Zn metal batteries. Here, the fundamentals of Zn electrode/electrolyte interface and the related issues are discussed. Thereafter, competent strategies including artificial protective layers, electrolyte optimization, structural engineering to fulfill a stable working Zn metal anode are presented. Subsequently, progressive characterization techniques reveal interfacial chemistries and morphological evolution of Zn metal anodes are outlined. Finally, the significantly perspective to guide and promote the developed of Zn batteries are proposed. This review will serve to further advance the development of interfacial engineering for Zn metal anodes.