Flexible Energy Storage Devices Research Articles

Conductive MXene/Polymer Composites for Transparent Flexible Supercapacitors.

Transparent flexible energy storage devices are limited by the trade-off among flexibility, transparency, and charge storage capability of their electrode materials. Conductive polymers are intrinsically flexible, but limited by small capacitance. Pseudocapacitive MXene provides high capacitance, yet their opaque and brittle nature hinders their flexibility and transparency. Herein, the development of synergistically interacting conductive polymer Ti3C2Tx MXene/PEDOT:PSS composites is reported for transparent flexible all-solid-state supercapacitors, with an outstanding areal capacitance of 3.1 mFcm-2, a high optical transparency of 61.6%, and excellent flexibility and durability. The high capacitance and high transparency of the devices stem from the uniform and thorough blending of PEDOT:PSS and Ti3C2Tx, which is associated with the formation of O─H…O H-bonds in the composites. The conductive MXene/polymer composite electrodes demonstrate a rational means to achieve high-capacity, transparent and flexible supercapacitors in an easy and scalable manner.

3D Architecting triple gradient graphene-based fiber electrode for high-performance asymmetric supercapacitors

High-performance fibrous architectures and controllable fabrication methods for active nanomaterials are fundamental in the development of fiber-based supercapacitors (FSCs). Herein, we rationally designed a triple gradient structured fibrous electrode based on three-dimensional (3D) architectural approach with Ni3S2 nanoflakes (Ni3S2 NFs) in situ growth on Ni-coated graphene fiber (Ni3S2-NiGFs) for highly energy-dense asymmetric supercapacitors. Remarkably, the Ni-metal coating imparted the Ni3S2-NiGFs exceptional electrical conductivity (619.8 S cm−1), mechanical strength (335.0 MPa), and flexibility without significantly compromising its density. Moreover, the unique 3D interconnected ultrathin Ni3S2 NFs significantly increase the contact area between the electrode and the electrolyte solution, providing abundant redox activity to facilitate ion transport and accumulation. Therefore, the fibrous electrode showcased a remarkable areal specific capacitance of 1387.6 mF cm−2 at 3 mA cm−2 in 3 M KOHaq electrolyte, while its asymmetric FSCs delivered an impressive areal energy density of 15.6 μW h cm−2 at power density of 1.0 mW cm−2 along with durable cycle life (86.7 % of the initial specific capacitance retention over 10,000 cycles). In summary, the featured work provides a facile but robust electrode design to realize highly energy-dense flexible energy storage devices for next-generation wearable industries.

Synthesis and self-assembly of bottlebrush block copolymer electrolytes for solid-state supercapacitors

All-solid-state supercapacitors have attracted increasing attention in recent decades owing to rapid advancements in safe, flexible, and wearable energy storage devices. This study demonstrates a bottlebrush block copolymer electrolyte consisting of poly(styrene-b-butadiene-b-styrene)-g-poly(ethylene glycol) behenyl ether methacrylate (SBS-g-PEGBEM) (simply SgP) for all-solid-state supercapacitors. Due to the adhesive nature and robust mechanical properties of SgP film, devices can be manufactured without the need for separators or packaging. The nonpolar SBS domains serve as scaffolds within the polymer matrix, while the polar PEGBEM domains offer interactive sites for polar ionic liquids (ILs). The synergy between precisely defined nanostructures and the subsequent well-dissociated ions enhances efficient ion transport through the ionic channels. As a result, the supercapacitor with SgP/IL electrolyte exhibits remarkable electrochemical performance. This includes a wide potential window of 2.4 V, an ionic conductivity of 2.4 mS cm−1, and maximum energy density and power density of 28.1 Wh kg−1 and 3080 W kg−1, respectively. The supercapacitor also demonstrates high cycle stability with 87.7 % capacitance retention after 5,000 cycles. The positive impact of the PEGBEM side chains is investigated via molecular dynamics simulations. Thus, this study presents a novel strategy for solid-state electrolytes, offering potential advancements in next-generation energy storage devices.

Scalable and economical production of oxygen deficient vanadium oxide with tunable vacancies concentration for bendable zinc ion batteries

Although vanadium oxides have high theoretical capacity and low cost, their practical application in aqueous zinc ion batteries (AZIBs) is bottlenecked by sluggish diffusion kinetics and capacity decline. Herein, the oxygen-deficient V2O5-x·nH2O (defined as VOd) with tunable oxygen vacancy concentration has been obtained via an economic and scalable method. The introduction of oxygen vacancies not only provides extra sites for Zn2+ storage, but also reduces the electrostatic barrier for Zn2+ intercalation, resulting in enhanced capacity and cycling stability. As a result, VOd cathode with proper amount of oxygen defect exhibits a high capacity of 415 mAh g−1 and energy density of 294 Wh kg−1 at 0.2 A g−1, estimating a roughly chemical costs of $64/kWH for VOd cathode. Besides, the VOd exhibits excellent stability at 20 A g−1 with average capacity decay of 0.004 % per cycle for 5000 cycles. Moreover, the bendable quasi-solid VOd//Zn battery maintains stable capacity of 200 mAh g−1 at 2 A g−1 even when repeatedly bending to straight angles. Therefore, the economical production of VOd cathode and construction of bendable quasi-solid battery provides a feasible way to boost the construction of efficient flexible energy storage devices and broadened application of AZIBs.

Polymeric Hydrogels for Energy Devices

Innovative energy storage devices, viz., supercapacitors and rechargeable batteries are of great awareness owing to their comprehensive claims in flexible electronics and implantations. In simple electronic devices, frequently facing problems like bending, collision, steeping, piercing, and even encountering shearing, fire, water, etc. Hence, a high mandate is needed for the constructive and consistency of energy storage devices. Hydrogels are hydrophilic three-dimensional polymers filled with water which are highly noticeable electrolyte materials due to their high-water permeability and smoothness, which enable them to fulfil the vital necessities for flexible energy storage devices. Hydrogels with intriguing physicochemical assets for justifiable energy storing for water production. The proposal of novel hydrogel electrolytes for supercapacitors and batteries with electrochemical performances for imminent growth. The biopolymeric hydrogel electrolytes can be chosen as substitute materials for supercapacitors due to their decent ionic conductivity, no fluid seepage, and no toxicity. Focus of the review aims to highlight the hydrogels materials combined into batteries and deliver thrilling tailorable architectures for multifunctionalities with amicable applications.

A Flexible One‐dimensional Woven Supercapacitor for Low‐power Smart Electronic Textiles

Flexible energy storage devices are attracting a great attention nowadays in the rapidly growing area of implantable/wearable electronics. This bloom has generated great demands on flexible wire‐shaped supercapacitors (WSC) as power sources in wearable electronic systems that can offer tunable sizes, shapes, and versatile designs. Herein, a flexible WSC is fabricated using MgMn2O4 nanofibers (MMO‐NFs) over a flexible carbon yarn substrate via the electrophoretic deposition method in the first report. The binder‐free deposition of highly porous and one‐dimensionally aligned MMO‐NFs over carbon yarn offers excellent ionic/charge transport into the fabricated device. The assembled WSC device at 0.1 mA/cm current rate shows capacitances of 386 mF/cm2 and 45.5 mF/cm. A capacitance retention of 88% for a WSC device after 10,000 cycles indicates its good cyclability. Further, the WSC exhibits good flexibility, retaining 94% of capacitance at 0.5 mA/cm after 2000 bending cycles. Furthermore, the flexible WSC device shows power and energy density of 744 μW/cm and 14.2 μWh/cm, respectively. Additionally, WSC devices demonstrate their practical energy storage capabilities in a video that shows three similar devices being knitted into a wearable glove and glowing a red light‐emitting diode (LED) for more than five minutes in various bending positions.

Interdigitated supercapacitor with double-layer active material prepared by sacrificial layer method

Increasing the surface area of active materials is a crucial approach to enhance the capacity of supercapacitors. In this study, we present an interdigitated supercapacitor featuring a double-layer active material prepared using a sacrificial layer method. The replacement of the insulating substrate with a gel electrolyte facilitates ion motion between the active electrodes. Finite element analysis (FEA) and electrochemical experiments confirm that the utilization of double-layer active material can significantly improve the capacity (1.5–1.85 times higher than traditional structures). The electrochemical performance of the three active materials has been significantly improved after using the double-layer active material structure, which proves that the method in this paper has strong material compatibility. Furthermore, an interdigital supercapacitor (ISC) is fabricated using electrodes with double-layer active material through the sacrificial layer method and its electrochemical performance is evaluated. At a scan rate of 10 mV·s-1, ISC exhibits an impressive area-specific capacitance as high as 68.4 mF·cm-2. Remarkably, ISC can maintain stable power output even under extreme deformation and fatigue testing conditions. This strategy involving interdigitated supercapacitors with double-layer active materials prepared via the sacrificial layer method presents a promising solution for flexible energy storage devices.

Conformal Engineering of Both Electrodes Toward High-Performance Flexible Quasi-Solid-State Zn-Ion Micro-Supercapacitors.

The severe Zn-dendrite growth and insufficient carbon-based cathode performance are two critical issues that hinder the practical applications of flexible Zn-ion micro-ssupercapacitors (FZCs). Herein, a self-adaptive electrode design concept of the synchronous improvement on both the cathode and anode is proposed to enhance the overall performance of FZCs. Polypyrrole doped with anti-expansion graphene oxide and acrylamide (PPy/GO-AM) on the cathode side can exhibit remarkable electrochemical performance, including decent capacitance and cycling stability, as well as exceptional mechanical properties. Meanwhile, a robust protective polymeric layer containing reduced graphene oxide and polyacrylamide is self-assembled onto the Zn surface (rGO/PAM@Zn) at the anode side, by which the "tip effect" of Zn small protuberance can be effectively alleviated, the Zn-ion distribution homogenized, and dendrite growth restricted. Benefiting from these advantages, the FZCs deliver an excellent specific capacitance of 125mFcm-2 (125Fcm-3) at 1mAcm-2, along with a maximum energy density of 44.4µWhcm-2, and outstanding long-term durability with 90.3% capacitance remained after 5000 cycles. This conformal electrode design strategy is believed to enlighten the practical design of high-performance in-plane flexible Zn-based electrochemical energy storage devices (EESDs) by simultaneously tackling the challenges faced by Zn anodes and capacitance-type cathodes.

A surface-induced assembly strategy to fabricate flexible carbon nanofiber/coal-based carbon dots films as free-standing anodes for high-performance sodium-ion batteries

Flexible electrodes with superior stability, high performance, and low cost have drawn numerous considerations in energy storage devices. Here, we developed a facile and robust strategy to prepare coal-based carbon dots (i.e., CDs) with high yields derived from lignite by microwave-assisted mild oxidation and further fabricate a carbon nanofiber film decorated with CDs (i.e., CNF@CDs) by electrospinning water-soluble CDs with polyacrylonitrile (i.e., PAN) through thermal treatment and carbonization and applied as flexible electrodes for sodium-ion batteries. The as-prepared CNF@CDs as binder-free anode presents a reversible capacity of 223 mAh g−1 at 20 mA g−1 and obtains a high capacity retention of 96% over 400 cycles. The outstanding electrochemical properties were attributed to the unique structure of CNF@CDs with the optimal ratio of carbon nanofiber and coal-based carbon dots, in which carbon fiber with the 3D framework facilitates the speed of ion diffusion and electron transport as well as the surface-induced assembly of CDs on the surface of the PAN fibers brings in strong structure stability and electrode integrity. The current study supplies a novel and effective approach to constructing flexible electrodes with superior stability and high performances from low-cost materials, which has potential application prospects in flexible energy storage devices.

Self-adhesive, freeze-tolerant, and strong hydrogel electrolyte containing xanthan gum enables the high-performance of zinc-ion hybrid supercapacitors

Hydrogel electrolyte is an ideal candidate material for flexible energy storage devices due to its excellent softness and conductivity properties. However, challenges such as the inherent mechanical weakness, the susceptibility to be frozen in low-temperature environments, and the insufficiency of hydrogel-electrode contact persist. Herein, a “Multi in One” strategy is employed to effectively conquer these difficulties by endowing hydrogels with high strength, freeze-resistance, and self-adhesive ability. Multiple hydrogen bond networks and ion crosslinking networks are constructed within the hydrogel electrolyte (PVA/PAAc/XG) containing polyvinyl alcohol (PVA), acrylic acid (AAc), and xanthan gum (XG), promoting the enhanced mechanical property, and the adhesion to electrode materials is also improved through abundant active groups. The introduction of zinc ions provides the material with superior frost resistance while also promoting electrical conductivity. Leveraging its multifunction of superior mechanical strength, anti-freeze property, and self-adhesive characteristic, the PVA/PAAc/XG hydrogel electrolyte is employed to fabricate zinc ion hybrid supercapacitors (ZHS). Remarkably, ZHS exhibits outstanding electrochemical performance and cycle stability. A remarkable capacity retention rate of 83.86 % after 10,000 charge-discharge cycles can be achieved at high current densities, even when the operational temperature decreases to −60 °C, showing great potential in the field of flexible energy storage devices.

One-step sustainable preparation of laser induced S-doped graphene for assembly of high-performance supercapacitors

Lignin, an industrial by-product that is abundant, renewable and has aromatic ring characteristics, is regarded as an ideal raw material for the synthesis of two-dimensional graphene materials. However, the sustainable development of graphene produced from lignin faces thorny challenges such as environmental pollution, low yield, cumbersome steps and harsh conditions. In this study, low-energy, green, large-scale one-step preparation of sulfur-doped graphene was achieved by co-blending lignin and sodium alginate into a fully biomass-based film, followed by easy-to-operate laser etching. Among them, alkaline lignin not only served as a carbon source but also acted as a sulfur doping source, avoiding the use of additional sulfur doping reagents. The results showed that the sheet resistance of graphene gradually decreased with the increase of laser power. The sheet resistance of graphene prepared when the laser power was 90% was as low as 8 Ω sq−1, which provided an inherent advantage for the subsequent assembly of flexible micro-supercapacitors. The specific capacitance and high energy density of the resulting supercapacitor were as high as 88.29 mF cm−2 and 12.26 μW h cm−2, respectively. This method successfully developed a sustainable and low-energy graphene preparation method, paving the way for the sustainable development of flexible energy storage devices.

3D Hierarchical Sunflower-Shaped MoS2 /SnO2 Photocathodes for Photo-Rechargeable Zinc Ion Batteries.

Photo-rechargeable zinc-ion batteries (PRZIBs) have attracted much attention in the field of energy storage due to their high safety and dexterity compared with currently integrated lithium-ion batteries and solar cells. However, challenges remain toward their practical applications, originating from the unsatisfactory structural design of photocathodes, which results in low photoelectric conversion efficiency (PCE). Herein, a flexible MoS2 /SnO2 -based photocathode is developed via constructing a sunflower-shaped light-trapping nanostructure with 3D hierarchical and self-supporting properties, enabled by the hierarchical embellishment of MoS2 nanosheets and SnO2 quantum dots on carbon cloth (MoS2 /SnO2 QDs@CC). This structural design provides a favorable pathway for the effective separation of photogenerated electron-hole pairs and the efficient storage of Zn2+ on photocathodes. Consequently, the PRZIB assembled with MoS2 /SnO2 QDs@CC delivers a desirable capacity of 366mAhg-1 under a light intensity of 100mWcm-2 , and achieves an ultra-high PCE of 2.7% at a current density of 0.125mAcm-2 . In practice, an integrated battery system consisting of four series-connected quasi-solid-state PRZIBs is successfully applied as a wearable wristband of smartwatches, which opens a new door for the application of PRZIBs in next-generation flexible energy storage devices.

Cross-Linked Polyacrylic-Based Hydrogel Polymer Electrolytes for Flexible Supercapacitors.

Hydrogel polymer electrolytes (GPEs), as an important component of flexible energy storage devices, have gradually received wide attention compared with traditional liquid electrolytes due to their advantages of good mechanical, bending, and safety properties. In this paper, two cross-linked GPEs of poly(acrylic acid-co-acrylamide) or poly(acrylic acid-co-N-methylolacrylamide) with NaNO3 aqueous solution (P(AA-co-AM)/NaNO3 or P(AA-co-HAM)/NaNO3) were successfully prepared using radical polymerization, respectively, using acrylic acid (AA) as the monomer, N-methylolacrylamide (HAM) or acrylamide (AM) as the comonomer, and N, N-methylenebisacrylamide (MBAA) as the cross-linking agent. We investigated the morphology, glass transition temperature (Tg), ionic conductivities, mechanical properties, and thermal stabilities of the two GPEs. By comparison, P(AA-co-HAM)/NaNO3 GPE exhibits a higher ionic conductivity of 2.00 × 10-2 S/cm, lower Tg of 152 °C, and appropriate mechanical properties, which are attributed to the hydrogen bonding between the -COOH and -OH, and moderate cross-linking. The flexible symmetrical supercapacitors were assembled with the two GPEs and two identical activated carbon electrodes, respectively. The results show that the flexible supercapacitor with P(AA-co-HAM)/NaNO3 GPE shows good electrochemical performance with a specific capacitance of 63.9 F g-1 at a current density of 0.2 A g-1 and a capacitance retention of 89.4% after 3000 charge-discharge cycles. Our results provide a simple and practical design strategy of GPEs for flexible supercapacitors with wide application prospects.

Biopolymer blend composite films based on polyvinyl alcohol/ chitosan/ grape seed extract via green approach for flexible optoelectronic devices

The flourishing environmental concerns have grabbed the attention of researchers developing environmentally supportive materials in various fields. A green approach was used to create biopolymer blend composites based on polyvinyl alcohol (PVA) and chitosan (CS) doped with various concentrations of grape seed (GS). Various analytical techniques, such as Fourier-transform infrared spectroscopy (FTIR), UV–visible (UV) spectra, field emission scanning electron microscope (FE-SEM) and differential scanning calorimetry (DSC) were used to evaluate the optical, structural and thermal properties of the prepared blend composites. The optical properties of blend composites were determined by UV spectroscopy and the findings revealed that absorption intensity increased with increasing GS, while bandgap energy decreased from 4.18 eV for pure blend to 2.91 eV for blend/15 wt% GS. The homogeneous distribution of GS particles in the biopolymer blend was identified with FE-SEM images. DSC results showed that increasing the GS content increased the glass transition temperature of the blend composites. The AC conductivity and dielectric constant were measured using the LCR meter. The conductivity rises with increasing frequency and dosage of GS, with the greatest conductivity obtained at 15 wt% loading. In comparison to a pure blend, it was discovered that the inclusion of 15 wt% GS enhanced the tensile strength by 50%, hardness by 17% and the reduction in elongation at break by 19 %. As a consequence, environmentally friendly PVA/CS/GS biopolymer blend composites with excellent mechanical, thermal, electrical, and dielectric parameters might be a viable green option for flexible electronic, electrochemical and energy storage devices.

PVDF/PI/BT nanocomposites with excellent charge/discharge efficiency obtained by inserting linear polymer to adjust the ferroelectricity

The problem of low charge/discharge efficiency of ceramic/polymer composites is still one of the hot topics in current research on dielectric materials. Here, we demonstrate that the ferroelectric property of ceramic/PVDF-based composites can be modulated by the introduction of linear polymer PI and the use of a spin-coating process. PI inhibits some polarization and partial dipole orientation by interacting with the molecular chains of the amorphous phase of PVDF and BT nanoparticles. As a result, the decrease in crystallinity and loss led to improved dielectric properties and charge/discharge efficiency. The findings demonstrate that the microstructure of PVDF-PI/BT nanocomposite is uniform and dense, with outstanding dielectric characteristics and high charge/discharge efficiency. The permittivities were stabilized in the range of 12.87–17.86 at 100 Hz, and the dielectric losses were all less than 0.27. Compared with the previously reported binary ceramic/polymer composites, the PVDF-PI/BT nanocomposites possessed a high charge/discharge efficiency with a small variation (63%-84%). This work offers an easy and efficient scheme to obtain nanocomposites with outstanding dielectric characteristics and charge/discharge efficiency. It may be a potential candidate for flexible dielectric substrates for advanced flexible capacitive energy storage devices.

One-step growth of ultrathin CoSe2 nanobelts on N-doped MXene nanosheets for dendrite-inhibited and kinetic-accelerated lithium–sulfur chemistry

The practical application of lithium–sulfur (Li–S) batteries is inhibited by the shuttle effect of lithium polysulfides (LiPSs) and slow polysulfide redox kinetics on the S cathode as well as the uncontrollable growth of dendrites on the Li metal anode. Therefore, both cathode and anode sides must be considered when modifying Li−S batteries. Herein, two-dimensional (2D) ultrathin CoSe2 nanobelts are in situ grown on 2D N-doped MXene nanosheets (CoSe2@N-MXene) via one-step solvothermal process for the first time. Owing to its unique 2D/2D structure, CoSe2@N-MXene can be processed to crumpled nanosheets by freeze-drying and flexible and freestanding films by vacuum filtration. These crumpled CoSe2@N-MXene nanosheets with abundant active sites and inner spaces can act as S hosts to accelerate polysulfide redox kinetics and suppress the shuttle effect of LiPSs owing to their strong adsorption ability and catalytic conversion effect with LiPSs. Meanwhile, the CoSe2@N-MXene film (CoSe2@NMF) can act as a current collector to promote uniform Li deposition because it contains lithiophilic CoSe2 and N sites. Under the systematic effect of CoSe2@N-MXene on S cathode and Li metal anode, the electrochemical and safety performance of Li–S batteries are improved. CoSe2@NMF also shows excellent storage performances in flexible energy storage devices.

Hydrophilic polyanionic hydrogel electrolyte for anti-freezing and bending resistant zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors (ZHSCs) have been widely considered as promising candidates for flexible electrochemical energy storage devices. The key challenge is to develop hydrogel electrolytes with high hydrophilicity, anti-freezing, bending resistance, and stable interface with electrodes. This study reported a hydrogel electrolyte system that can meet the above functions, in which the zincophilic and negatively charged SO3−, migratable Na+, abundant hydrophilic functional groups, gum xanthan, and porous architecture could effectively promote the electrochemical performance of ZHSCs. ZHSCs with such hydrogel electrolytes not only exhibited good low-temperature performance but also showed excellent bending resistance ability. A high specific capacitance could be kept after a long air-working lifespan over 10,000 cycles under a wide operation voltage of 1.85 V at −10 °C. Furthermore, flexible ZHSCs could maintain the capacitance retention of 93.18% even after continuous 500 bends at an angle of 180°. The designed hydrogel electrolytes could be also used for other electrochemical energy storage devices with anti-freezing and bending resistance by changing electrolyte salt.

Robust optimal operation scheduling method for integrated energy system considering flexible energy storage and mixed hydrogen natural gas

ABSTRACT At present, the number of electric vehicles is increasing day by day. The full integration of electric vehicles and multi-energy coupled integrated energy systems is the future development trend. This paper introduces a novel form of flexible energy storage in the integrated energy system ;(IES): electric vehicle (EV). And It proposes that mixed natural gas hydrogen be used as the primary energy source for IES, which replaces traditional natural gas. Combined with the above, the IES is scheduled to meet the system’s multi-load for heating, cooling, and electricity demands. Based on the integrated energy system’s structure and energy conversion principles, a robust two-stage optimization model for the IES is proposed to minimize the daily operation scheduling costs. The proposed model considers the uncertainty of distributed renewable generation and flexible energy storage. Uncertain adjustment parameters are introduced into the model, which can flexibly adjust the conservatism of the scheme. Using the column and constraint generation algorithm (C&CG) and the strong duality theory, the model presented in this paper is solved and the optimal scheduling scheme is obtained. The final simulation results validate the effectiveness of the model and algorithm. The addition of flexible energy storage and mixed natural gas hydrogen effectively improves the economy and flexibility of the system while reducing carbon emissions costs. Consideration of uncertainty improves system robustness and safety. In addition, sensitivity analyses of the influence of the proportion of hydrogen mixed with natural gas, the setting of uncertain adjustment parameters, electricity prices, weather, and load fluctuations on system operation. The results show that compared to existing research, electric vehicles as a flexible energy storage device and mixed natural gas hydrogen supply, increase the economic benefits of IES by 19.8% and 23%, respectively.

Three-dimensional Ordered Macroporous Flexible Electrode Design toward High-Performance Zinc-Ion Batteries.

Flexible zinc-ion batteries (ZIBs) have been considered to have huge potential in portable and wearable electronics due to their high safety, cost efficiency, and considerable energy density. Therein, the design and construction of flexible electrodes significantly determine the performance and lifespan of flexible battery devices. In this work, an ultrathin flexible three-dimensional ordered macroporous (3DOM) Sn@Zn anode (60 μm in thickness) is presented to relieve dendrite growth and expand the lifespan of flexible ZIBs. The 3DOM structure can ensure uniform electric field distribution, guide oriented zinc plating/stripping, and extend the lifespan of anodes. The rich zincophilic Sn sites on the electrode surface significantly facilitate Zn nucleation. Accordingly, a lowered nucleation overpotential of 8.9 mV and an ultralong cycling performance of 2400 h at 0.1 mA cm-2 and 0.1 mAh cm-2 are achieved in symmetric cells, and the 3DOM Sn@Zn anode can also operate in deep cycling for over 200 h at 10 mA cm-2 and 5 mAh cm-2. A flexible 3DOM MnO2/Ni cathode with a high structural stability and a high mass-specific capacity is fabricated to match with the anode to form a flexible ZIB with a total thickness of 200 μm. The flexible device delivers a high volumetric energy density of 11.76 mWh cm-3 at 100 mA gMnO2-1 and a high average open-circuit voltage of 1.5 V and exhibits high-performance power supply under deformation in practical application scenarios. This work may shed some light on the design and fabrication of flexible energy-storage devices.

An interface-integrated hydrogel for all-in-one flexible supercapacitor with excellent wide-temperature and self-healing properties

With the rapid development of flexible energy storage devices, the abilities to withstand various of mechanical deformation and maintain stable electrochemical performance at different temperatures are two decisive factors that stand out in their applications. Herein, aniline containing 2-acrylamido-2methylpropane sulfonic acid sodium is polymerized in-situ on hydrogels with double cross-linked networks constructed by polyacrylamide, polyvinyl alcohol and quaternary ammonium salt of chitosan through electrostatic interaction, so as to obtain the PPHP-Na hydrogels for the construction of the all-in-one flexible supercapacitors. The PPHP-Na hydrogels can withstand a maximum of 544% tensile strain at tensile stress up to 601 kPa, and can maintain stable dissipation during stress-strain tensile cycles and recover quickly after cycling, exhibiting excellent mechanical properties. In addition, the optimal PPHP-Na hydrogel shows a high ionic conductivity of 65.6 mS cm−1. More importantly, as an all-in-one flexible energy storage device, the PPHP-Na supercapacitor shows high area capacitance of 250.75 mF cm−2, and can maintain relatively stable electrochemical performance at -40-80 °C and good self-healing property. This interface-integrated strategy of all-in-one flexible supercapacitors with excellent and stable electrochemical performance constructed provides meaningful ideas for the development of flexible electronic devices.