High Electrochemical Performance Research Articles

Delocalized Isoelectronic Heterostructured FeCoOx Sy Catalysts with Tunable Electron Density for Accelerated Sulfur Redox Kinetics in Li-S batteries.

High interconversion energy barriers, depressive reaction kinetics of sulfur species, and sluggish Li+ transport inhibit the wide development of high-energy-density lithium sulfur (Li-S) batteries. Herein, differing from random mixture of selected catalysts, the composite catalyst with outer delocalized isoelectronic heterostructure (DIHC) is proposed and optimized, enhancing the catalytic efficiency for decreasing related energy barriers. As a proof-of-content, the FeCoOx Sy composites with different degrees of sulfurization are fabricated by regulating atoms ratio between O and S. The relationship of catalytic efficiency and principal mechanism in DIHCs are deeply understood from electrochemical experiments to in situ/operando spectral spectroscopies i.e., Raman, XRD and UV/Vis. Consequently, the polysulfide conversion and Li2 S precipitation/dissolution experiments strongly demonstrate the volcano-like catalytic efficiency of various DIHCs. Furthermore, the FeCoOx Sy -decorated cell delivers the high performance (1413 mAh g-1 at 0.1 A g-1 ). Under the low electrolyte/sulfur ratio, the high loading cell stabilizes the areal capacity of 6.67 mAh cm-2 at 0.2 A g-1 . Impressively, even resting for about 17 days for possible polysulfide shuttling, the high-mass-loading FeCoOx Sy -decorated cell stabilizes the same capacity, showing the practical application of the DIHCs in improving catalytic efficiency and reaching high electrochemical performance.

Synthesis of Mo 2C MXene with high electrochemical performance by alkali hydrothermal etching

Synthesis of Mo ₂C MXene with high electrochemical performance by alkali hydrothermal etching

A quasi‐solid polymer electrolyte‐based structural battery with high mechanical and electrochemical performance

AbstractStructural batteries are attractive for weight reduction in electric transportation. For their practical applications excellent mechanical properties and electrochemical performance are required simultaneously, which remains a grand challenge. In this study, we present a new scalable and low‐cost design, which uses a quasi‐solid polymer electrolyte (QSPE) to achieve both remarkably improved flexural properties and attractive energy density. The QSPE has a high ionic conductivity of 1.2 mS cm−1 and retains 91% capacity over 500 cycles in graphite/NMC532 cells. Moreover, the resulting structural batteries achieved a modulus of 21.7 GPa and a specific energy of 127 Wh kg−1 based on the total cell weight, which to our knowledge is the highest reported value above 15 GPa. We further demonstrate the application of such structural batteries in a model electric car. The presented design concept enables the industrialization of structural batteries in electric transportation and further applications to improve energy efficiency and multifunctionality.image

Polyaniline Films Fabricated by Pre‐Nucleation Electrodeposition Method with High Electrochemical Activity: Parameter Optimization and Analysis

AbstractElectrochromic polyaniline (PANI) films with high electrochemical performance have been intensively pursued for their potential applications in various fields. Here, the growth process of the PANI films synthesized by the pre‐nucleation electrodeposition method is analyzed and the optimal parameters with highest electrochemical activity are obtained. The PANI film fabricated under high current density of 10 mA cm−2 and impact time of 0.2 s shows the best electrochemical performance. It has a maximum active charge of 22.3 mC cm−2. The optimum electrochemical performance is attributed to the loose and porous structure. The PANI films fabricated under the optimal parameters also show the flattest structure and the smooth surface. It concludes a universal evaluation basis of the optimal conditions for the pre‐nucleation method. That is, in the nucleation stage, the potential curve shall peak rapidly and then fall slowly to the valley without any upward growth; when entering into the low current density growth stage, the potential shall fall rapidly to a certain value and grow at that potential smoothly. This work evokes a deeper understanding and controlling of the growth process of polymers.

Preparation of a High-Performance Asymmetric Supercapacitor by Recycling Aluminum Paper and Filter Components of Heated Tobacco.

In this study, Al paper and cellulose acetate (CA) filters derived from heated tobacco waste were successfully converted into current collectors and active materials for a supercapacitor device. Typically, heated tobacco contains electrically discontinuous Al paper. First, Al was extracted from the tobacco waste using HCl to produce Lewis acid (AlCl3). This acid was then used in an Al electrodeposition process utilizing the chloroaluminate ionic liquid reaction between the acid and the base (RCl) at room temperature. To enhance the conductivity, a supplementary coating of Al metal was applied to the Al paper through electrodeposition, thus re-establishing the electrical continuity of the discontinuous parts and forming an Al-coated current collector. Moreover, the CA filters were carbonized under a nitrogen atmosphere, yielding carbon precursors (C-CA) for the supercapacitor electrodes. To further enhance the electrochemical performance, nickel oxide (NiO) was incorporated into C-CA, resulting in C-CA@NiO with pseudocapacitance. The specific surface area of CA increased with carbonization and the subsequent incorporation of NiO. The as-synthesized C-CA and C-CA@NiO materials were applied to an Al-coated current collector to obtain C-CA- and C-CA@NiO-based electrodes, exhibiting stable electrochemical behavior in the voltage range of -1.0 to 0 V and 0 to 1.0 V, respectively. An asymmetric supercapacitor (ASC) device was assembled with C-CA@NiO and C-CA as the positive and negative electrodes, respectively. This ASC device demonstrated a high specific capacitance of 40.8 F g-1, while widening the operating voltage window to 2.0 V. The high electrochemical performance of the device is attributed to the successful Al electrodeposition, which facilitates the electrical conductivity and increased porosity of the C-CA@NiO and C-CA materials. To the best of our knowledge, this is a pioneering study in regards to the conversion of biomass waste into current collectors and active materials to fabricate a practical ASC device. Our findings highlight the potential of reusing Al paper and CA filters from heated tobacco waste as essential components of energy storage devices.

Supramolecular design strategy of cyclodextrin polymer-polyaniline/hollow carbon spheres with core-shell nanostructures for supercapacitor

Controllable polymerization is of great significance for the design of nanoscale devices with high electrochemical performances. In this study, cyclodextrin polymer (CDP)-functionalized polyaniline (PANI)/hollow carbon sphere (HCS) composites were prepared by an in-situ polymerization strategy. HCSs were used as carbon structural templates. CDP can be decorated with a controllable PANI layer owing to supramolecular interactions, effectively preventing the problem of secondary growth of PANI during the polymerization of aniline. Consequently, the integration promotes the more consistent growth of PANI on HCS and further ameliorates the capacitance performance of CDP-PANI/HCS. In a three-electrode system, the specific capacitance of PANI/HCS at 1 A g−1 was 390 F g−1, which can be increased to 569 F g−1 after CDP-induced polymerization. CDP-PANI/HCS shows a high energy density of 24.5 Wh∙kg−1 at a power density of 700 W kg−1, and the energy density still retains 15.5 Wh∙kg−1 even at a higher power density of 14000 W kg−1. Thus, the strategy established in this work has great potential for improving the growth of polymers via CDP-assisted polymerization.

Laser-induced reduction and pattern regulation of graphene oxide film with high biosafety for wearable micro-supercapacitors

A two-step laser process consisting of surface treatment and pattern scribing was developed to prepare micro-supercapacitors (MSCs) with high electrochemical performance and structural robustness. First, an ultrathin and uniform graphene oxide (GO) film was deposited onto a copper foil by electrophoretic deposition, after which a laser beam with a wavelength of 450 nm was used to remove the oxygen-containing functional groups and introduce porous structures into the GO film. Subsequently, another laser beam with a wavelength of 1064 nm was used to scribe the film to form finger-patterned electrodes. After being assembled into flexible MSCs, the volume specific capacity of the MSCs reached 1.94 F cm−3, and the power and energy densities reached 4 mW cm−3 and 0.172 mWh cm−3, respectively. After 7000 charge-discharge cycles, the device showed excellent cycling stability with a capacitance retention rate of ∼87.5%. Moreover, the MSCs could be bent into different forms with marginal capacitance loss, confirming their high structural tolerance. Remarkably, the laser-irradiated GO (L-GO) film showed high biosafety toward human empirical cells in the biotoxicity tests, indicating that the devices could be adopted as reliable micro-devices with high biosafety for fabricating wearable electronics on human skin.

Preparation of V2O5 nanobelt arrays/NiO nanosheet arrays composite as supercapacitor electrode material

V2O5 nanobelt arrays (VNBAs) is fabricated on Ni foam by using an easy hydrothermal route and then NiO nanosheet arrays (NNSAs) is grown on VNBAs by using a simple chemical bath deposition approach to form VNBAs/NNSAs composite. It is found that the monocrystalline VNBAs with a lamellar structure is uniformly distributed on nickel foam and the polystalline NNSAs with a close packed structure is closely covered on the VNBAs. CV, GCD, EIS and CA electrochemical techniques are used to test the supercapacitive properties of the VNBAs/NNSAs composite. The single electrode displays a high specific capacity of 875 F g−1, a good cycling stability of 96.1%, a small charge transfer resistance of 1.32 Ω and a rapid ion diffusivity of 2.5 × 10−8 cm2 s−1. The symmetric supercapacitor combined by the VNBAs/NNSAs displays a large energy density of 120.1 W h kg−1 at 400 W kg−1 and it retains 68.3 W h kg−1 at 8000 W kg−1. The VNBAs/NNSAs composite with high electrochemical performance is a potential supercapacitor electrode material.

Well-integrated bismuth trioxide nanotriangles on carbon cloth as a flexible faradic electrode for supercapacitor applications

The development of redox-active and binder-free materials using facile synthesis methods has attracted great attention in the fabrication of high-performance energy storage devices. In this work, we have used a simple electrochemical deposition method for the direct growth of bismuth trioxide nanostructures on carbon cloth (Bi2O3/CC) for electrochemical supercapacitors (SCs). The as-synthesized Bi2O3 electrode appeared to be triangle-shaped nanostructures with robust adhesion and good crystallinity on a flexible CC electrode. The binder-free Bi2O3/CC electrode has been directly used as an SC electrode, which demonstrated battery-type redox behavior with high electrochemical performance. The low charge transfer resistance (3.9 Ω) of the binder-free Bi2O3/CC electrode demonstrated a specific capacity of 105.5C/g at a current density of 1 A/g with good rate capability at 12 A/g. Moreover, Bi2O3/CC showed good cycling stability of 70.6 % after 2000 consecutive charge-discharge cycles. Considering the simple and direct growth of anode materials, this work could unlock the enormous potential for the development of negative electrode material in hybrid SCs with excellent energy storage properties.

An imidazole-philic dispersible ionic liquid provides ample proton transport channels and high proton performances for high temperature proton exchange membranes

Abundant proton transport channels in polybenzimidazole proton exchange membranes (PBI-PEMs) has been considered as the guarantee of high electrochemical performances for high-temperature proton exchange membrane fuel cells (HT-PEMFCs). Porous structures are widely employed to create the channels. However, low mechanical properties of membranes results from chaotic aggregated pores hinders the application. In this study, the membrane of continuous micro-porous structure was innovatively fabricated via self-assembly of 1-Allyl-3-methylimidazolium chloride ([AmIm]Cl) in PBIs. The ionic liquid (IL) form continuous phases among PBI chains with inter-molecular distances less than 5 Å. The uniform porous structure enables tighter segment packing of polymer, creating uninterrupted PA channels that significantly enhanced proton transport efficiency without undermining the mechanical properties. The resulting micro-porous membrane displayed exceptional power density of 717.7 mW cm−2 at 160 °C, with 0.6 mg cm−2 Pt loading, accompanied by remarkable tensile strength of 12.4 MPa. Moreover, the catalyst layer exhibited superior oxygen diffusivity by optimizing the PA uptake. These results indicate that the micro-porous structure driven by the imidazole-philic dispersible ionic liquid is an effective strategy for designing high-performance PEMs.

Enhanced water retention in carbon nanotube sheets-sandwiched gas diffusion layer in polymer electrolyte membrane fuel cells operated under low humidity conditions

This study introduces the polymer electrolyte membrane fuel cell (PEMFC) using sandwiched-carbon nanotube (CNT) sheets into the gas diffusion layer (GDL). The CNT sheegts are synthesized via floating catalyst chemical vapor deposition and formed into sheets using the direct spinning technique. The sandwiched-CNT sheets PEMFC indicates high electrochemical performance across a range of relative humidity conditions, remarkably in non-humidified conditions of the cathode. This notable achievement can be attributed to the distinctive physical properties of the CNT sheets. In contrast to the microporous layers, the CNT sheets possess a nanoporous structure that enhances reactant diffusion, and appropriate hydrophobicity enhances the water retention capacity in GDL. These properties are confirmed by polarization curves, electrochemical impedance spectroscopy (EIS), quantitative capillary pressure, and water removal rate test in constant current mode at 0.4 A/cm2. In the non-humidified cathode condition, the peak power density of the sandwiched-CNT sheets PEMFC is 45% higher than conventional PEMFC. Moreover, it demonstrates significantly reduced ohmic resistance in EIS. The water retention capability of the PEMFC is assessed through quantitative capillary pressure and water removal rate test. Based on these assessments, we validate that the sandwiched-CNT sheets PEMFC exhibits high performance even under non-humidified cathode conditions.

Nanowire sulfide/carbon composite with high electrochemical performance in potassium-ion batteries

Transition metal chalcogenides (TMCs) have demonstrated great potential in energy storage devices due to their versatile structures and composite functionalities. However, the application of TMCs in potassium-ion batteries (PIBs) suffers from the issues of large volume expansion, polysulfide dissolution, and sluggish kinetics. To overcome these challenges, this work develops nano-flower-like MnS-Co3S4 confined in poly-pyrrole (PPY) carbon nanotube (denoted as MS-CS-PPY) as an excellent anode in PIBs. The nitrogen-doped PPY framework facilitates the interface electron transfer, confines active materials MS-CS effectively, and mitigates the volume change, thus resulting in boosted reaction kinetics and exceptional cycling stability. TMCs induce the surface capacitance and enable the chemical anchoring of the charge/discharge products during the potassium/de-potassium process. Moreover, this work reveals the potassium/de-potassium reaction mechanism, redox kinetics, and solid electrolyte interphase formation of MS-CS-PPY in different electrolytes through theoretical calculations and experimental studies. The solvation ability of electrolytes plays a vital role in manipulating the redox kinetics of the MS-CS-PPY anode material. This study offers feasible strategies for electrode design and electrolyte selection for developing TMCs negative electrodes in future PIBs.

Electrical bridging effects of dual-carbon microsphere frameworks in Si-based composite anodes for high-performance Li-ion batteries

Herein, the successful fabrication of a high-performance Si-based composite Li-ion battery (LIB) anode, comprising a dual-carbon framework of reduced graphene oxide (r-GO) and oxidized single-walled carbon nanohorns (o-NHs), was demonstrated using a simple and scalable spray-drying process followed by heat treatment (h-s-GO/Si/NH). The r-GO nanosheets in the h-s-GO/Si/NH anode acted as a robust spherical framework that facilitated the mechanical and electrical connection between the carbon-coated Si (c-Si) nanoparticles, homogeneous dispersion of c-Si and o-NH nanoparticles, and suppression of the volume expansion and pulverization that occur during lithiation/delithiation. Additionally, the o-NH nanoparticles incorporated in the h-s-GO/Si/NH composite served as electrical bridges between the r-GO nanosheets, resulting in enhanced electrical conductivity and effortless Li-ion shuttling. The h-s-GO/Si/NH composite anode exhibited high electrochemical performance with a very high initial gravimetric charge capacity (2961 mAh g−1 at 0.1 A g−1), stable initial Coulombic efficiency (80.6% at 0.2 A g−1), and high cycling stability (983 mAh g−1 at 0.2 A g−1 after 50 cycles). This study highlights the importance of the effective design of electrically conductive three-dimensional frameworks in Si-based composite anodes, which may contribute to the development of high-performance LIB anode materials.

3D heterostructure constructed by few-layer 1T MoS2 and MXene under high electrostatic fields for high-performance supercapacitors

Electrostatic spray deposition (ESD) is a promising technique for preparing high-quality heterostructure materials to achieve high electrochemical performance. Moreover, the materials obtained by ESD possesses well-dispersed, bonder-free and easy-control advantages. Herein, we firstly report that 1T MoS2/Ti3C2Tx heterostructure material is successfully constructed by few-layer 1T MoS2 and Ti3C2Tx MXene through ESD. The construction of heterostructure by high electrostatic fields is able to solve problem of agglomeration of layered materials, improve conductivity and stabilize 1T MoS2 to realize outstanding electrochemical performance of supercapacitor. As expected, the binder-free 1T MoS2/Ti3C2Tx heterostructure displays an excellent specific capacitance (1198 mF cm−2 at 3 mA cm−2), a high rate performance (45% as current density from 3 to 20 mA cm−2) and long-cycle life (73.8% capacity retention after 7000 cycles at 20 mA cm−2). More interestingly, a simple and efficient route to prepare 2D/2D heterostructure electrode for storing energy can be extended to other materials.

In‐Built Polaronic States Self‐Regulation for Boosting Potassium‐Ion Diffusion Kinetics

AbstractPotassium ion batteries (PIBs) have attracted enormous attention due to their low cost and high abundance of potassium resources. Here, self‐hybridized BiOBr0.5I0.5 with a flower‐like structure composed of 2D nanosheets is assembled and used as PIBs anode. According to the systematic theoretical calculations, the unbalanced charge distribution between Br and I atoms induces an intensified internal electric field and a wide van der Waals gap; while the decreasing of electron polarons caused by the hybridized structure improves the stability and electronic conductivity of the system. Moreover, the K+ ion uptake induces an energetic evolution in polaronic states in the BiOBr0.5I0.5 crystal skeleton, whereby the dynamic K+ ion‐halogen atoms correlation in situ forms hole‐like polarons, which substantially promotes K+ ion diffusion kinetics and the corresponding reaction kinetics during charge/discharge processes, imparting significant implications for the design of high‐performance energy storage electrode materials by engineering the interface interaction and electronic structure. Therefore, with this atomic orbital self‐hybridized structure, the K+ ion diffusion kinetics and the corresponding reaction kinetics during the charge/discharge process are both enhanced remarkably, thus enabling a high electrochemical performance of 155 mAh g−1 at 1000 mA g−1 over 4000 cycles in PIBs with the BiOBr0.5I0.5 as the anode.

Preparation of SiO2 Nano Matrix Engendered from Coal Fly Ash Encrusted with NiFe2O4 Nanocomposites for High Electrochemical Performance

Preparation of SiO2 Nano Matrix Engendered from Coal Fly Ash Encrusted with NiFe2O4 Nanocomposites for High Electrochemical Performance

Designing p-n heterostructure of LSCF-CeO2 material for ionic transportation as an electrolyte for semiconductor ion membrane fuel cell

Development of protonic ceramic fuel cells (PCFCs) electrolyte with fast ionic conduction and high electrochemical performance at low temperature is highly desirable for the hydrogen suitable application. In this regard, semiconductor heterostructure of LSCF-CeO2 is designed by introducing n-type CeO2 into p-type semiconductor material La0.8Sr0.2Co0.8Fe0.2O3-δ (LSCF) to construct a p-n heterojunction structure. This work discusses the role of semiconductor charge separation in fuel cell device on electrochemical performance by interesting physical and electrochemical characterizations in terms of energy band alignment, oxygen vacancies formation and Schottky junction. Further, the constructed LSCF-CeO2 heterojunction composites by combining CeO2 and LSCF with different concentrations tested the electrochemical performance as electrolyte to assemble fuel cell devices with significant power densities and high ionic conductivity of 0.11 S/cm. By comparison, it is found that the LSCF-CeO2 heterojunction composite constructed with 20% molar ratio of CeO2 play a better role in preventing electron transport, reflecting ionic conductivity and a pretty power output.

Electrochemical determination of Vitamin B6 using coral-like MnO2-Pi on Ti3C2Tx MXene

MXenes are 2D nanomaterials that are considered the materials of the future generation due to their high electrical conductivity, good biocompatibility, and ease of functionalization. This research work reports the electrochemical sensing of Vitamin B6 using the Manganese dioxide-inorganic phosphate/MXene brush-coated Carbon fiber paper electrode (MnO2-Pi/MXene/CFP) electrode for the first time. The three-dimensional Ti3C2Tx MXene nanosheets consisting of highly ordered, vertically aligned nanosheets with electrochemically deposited MnO2-Pi are capable of yielding a synergistic effect in combination with high electrochemical performance and large surface area of MnO2-Pi. The reported electrochemical sensor exhibited a wide linear dynamic range (0.06–650 µM) and a low-level detection limit of 0.021 µM. An increase in the anodic peak current confirms the rapid transfer of electrons transfer arising between the Ti3C2Tx MXene and MnO2-Pi. The results attained substantiate that the fabricated sensor has enhanced selectivity, reproducibility, and stability toward the electrochemical determination of Vitamin B6 in real samples.

Constructing PTFE@LATP composite solid electrolytes with three-dimensional network for high-performance lithium batteries

The NASICON-type lithium aluminum titanium phosphate (LATP) solid-state electrolytes is considered as a promising candidate for next-generation all-solid-state lithium batteries (ASSLBs) with high energy density. However, LATP possesses highly interfacial impedance, causing poor electrochemical performance of ASSLBs and seriously hindering its practical application. Herein, the (polytetrafluoroethylene) PTFE@LATP composite solid electrolytes with three-dimensional network have been constructed by combining sol-gel and solid state grinding methods. The electrochemical performance test results show that the introduction of 24 wt% PTFE can effectively reduce the interface impedance of LATP (LATP:2010.0 Ω, PTFE@LATP:126.9 Ω), increased ion conductivity of LATP (LATP:5.50 × 10−5 S∙cm−1, PTFE@LATP:7.56 × 10−4 S∙cm−1), further significantly improve the electrochemical window (LATP:3.2 V, PTFE@LATP:5.0 V), rate capability (corresponds to 95.2% of the initial discharge capacity) and cycling stability (the capacity of the full cell is changed from 140.1 mAh∙g−1 to 88.3 mAh∙g−1 after 500 cycles at 1 C) of ASSLBs. Mechanism research indicates that PTFE@LATP with the excellent electrochemical performance benefits from PTFE@LATP CSEs with three-dimensional network and electrode possess well interface compatibility, it conducive to preventing the occurrence of interface side reactions and promoting the rapid migration of lithium ions. This work provides a theoretical basis and practical guidance for the further development of CSEs with higher electrochemical performance.

Carbon nanofiber-supported elongated square bipyramid-like MnWO4 composite electrodes for high-performance battery-type supercapacitors: Enhanced electrochemical performance via synergistic effect

Battery-type electrode materials known for high electrochemical performance are commonly paired with carbon-based materials, which have recently gained attention for their potential application in supercapacitors. These carbon-based materials offer the potential for comprehensive energy storage properties along with excellent cycle life. In this study, a carbon nanofiber (CNF)-based elongated square bipyramid-like manganese tungstate (MnWO4; MnW) composite was synthesized via a simple and cost-effective solid-state reaction followed by an impregnation method. The main objective was to understand the synergistic effects of varying the content of CNF in the reaction on the formation of two different composites (MnW-CNF@L and MnW-CNF@H) and their physicochemical and electrochemical properties were thoroughly examined and compared to those of the MnW. Pure composites have a high crystalline nature with bipyramid-shaped microstructures anchored on the one-dimensional (1D) tubular CNF backbone, as confirmed by the structural and morphological analysis. In the context of the battery-type supercapacitor, the specific capacity is 2-fold higher for MnW-CNF@L (235.3 mAh g−1/848.1 C g−1) and 4-fold higher for MnW-CNF@H (451.3 mAh g−1/1624 C g−1) compared to the MnW (11.8 mAh g−1/402.6 C g−1) electrode at a current density of 1 A g−1. In addition, the MnW-CNF@H composite electrode delivered 96% capacity retention when current density increased 20-fold and exhibited outstanding cyclic stability of 95% initial capacity retention after 5,000 cycles. A solid-state hybrid supercapacitor was fabricated using the battery-type MnW-CNF@H composite electrode as the cathode and activated carbon (AC) as the anode. The MnW-CNF@H//AC HSC device configuration resulted in remarkable performance metrics, displaying a high energy density of 48.9 Wh kg−1 at 1018.2 W kg−1. The exceptional performance of this composite can be attributed to the synergistic effect among redox centres of Mn, W, and CNF. This work broadcasts a simple and cost-effective approach for designing high-performance supercapacitors, contributing to the development of sustainable energy storage systems.