Practical Energy Storage Devices Research Articles

MgO templated carbons: Effect of synthesis methodology on the morphology, surface chemistry and supercapacitor performances

Templating method is a widely adopted route to prepare porous carbon, while the effect of methodology on the structure and performances of the derived porous carbon was rarely focused. Herein, we employed a commercial MgO as template and catechol/formaldehyde as starting materials to prepare porous carbon by incipient impregnation method (the derived product denoted as MgC-I) and aqueous self-assembly method (the derived product denoted as MgC-S), respectively. Systematically analysis indicates that impregnation method favors the construction of two-dimensional structure, while, aqueous self-assembly method benefits formation of densified structure. Concerning to the surface chemistry, aqueous self-assembly method enables more residual oxygenic functionalities than that of impregnation derived ones. As electrode for supercapacitor in aqueous electrolyte, the MgC-S achieves superior volumetric performances including high specific volumetric capacitance of 319 F/cm3@1.0 A/g and large energy density of 27.9 Wh/L@1193 W/L, showing a potential for practical energy storage devices. Whereas, in organic electrolyte of 1.0 M TEANBF4/AN, the MgC-I electrode show a superior energy storage ability with energy density of 40.5 Wh kg−1@1350 W kg−1, the value is about six times higher than that of MgC-S based one. This study provides a reference for how to choose synthesis methods for preparing carbon materials with specific target.

Highly efficient alkaline aqueous MXene-based asymmetric supercapacitors developed by corrugation-like MoS2 and WS2 modified CMX electrodes

The preparation of superior performance supercapacitors to achieve high energy density, fast charge-discharge speed and long cycle stability characteristics has become the focus of attention to realize their potential as practical energy storage devices. In this paper, a cross-linking CNTs@MXene (CMX) architecture is selected as the negative electrode to increase the contact area with electrolyte, and corrugation-like morphologies MoS2 and WS2 nanoparticles modified CMX (Mo/W-CMX) two-dimensional nanostructure as the positive electrode to provide multiple ion diffusion through its channels structure, which presents good electrochemical performance with high specific capacitance and high energy density in 1 M KOH alkaline electrolyte. CNTs introduced into MXene interface by bridges can effectively impede the re-stacking of MXene, meanwhile, CMX as a matrix can also alleviate the properties degradation caused by the agglomeration and volume strain for sulfides. Benefiting from the facilitate accessibility of ions and high ability of electron transfer, the prepared Mo/W-CMX electrode exhibits a dramatic specific capacitance of 1160 F g−1 at 1 A g−1 and excellent capacitance retention of 88.67% at 25 A g−1 after 10,000 cycles. Meanwhile, the assembled asymmetric supercapacitor (Mo/W-CMX // CMX) presents an ultrahigh energy density of 28.1 Wh kg−1 at the power density of 697.3 W kg−1 and maintains 81.25% cycle stability at 15 A g−1 for 10,000 charge-discharge cycles. It is essential to highlight that the superior performance fabricated asymmetric supercapacitor holds a wide application prospect and very competitive energy-storage values in the upgrading of new high-performance devices.

Sputtered vanadium carbon nitride (VCN) thin films: a potential electrode for supercapacitors

The preparation of efficient thin film-based electrode materials is a vital prerequisite for practical energy storage devices. Herein, we have prepared unique vanadium carbon nitride (VCN) thin films on FTO substrates by pulsed DC magnetron sputtering technique for competent supercapacitor electrodes. XRD analysis confirmed the crystalline nature of VCN thin films. SEM and AFM revealed a smooth morphology with an average grain size of 30 nm. Raman spectra showed two broad peaks around 1346 and 1589 cm−1, belonging to the D-band and G-band of VCN. The surface electronic states of VCN were investigated by XPS analysis, which confirmed the formation of pure VCN films without any impurities. The electrochemical performance of the thin film electrode was evaluated using cyclic voltammetry (CV), Galvanostatic charge–discharge (GCD), and Electrochemical impedance analysis (EIS). The electrochemical results showed the VCN thin films exhibited super capacitive behaviours. The maximum specific capacitance (Cs) value of 78.2 F g−1 was obtained from GCD studies. A variation in charge transfer resistance is detected from the EIS study, which arises due to the partial oxidation of the active nitride component. The VCN electrode showed good cycling stability, retaining 87% of its capacitance at a current density of 5 A g−1 even after 2000 cycles. The sputtered VCN films have been demonstrated as potential thin film electrodes for electrochemical supercapacitors for practical energy storage devices.

Nanocrystals Conversion Chemistry within Slit-like 2D-Nanogap for High-Rate Cyclic Stability of Lithium-Ion Battery Anodes

A deep understanding of nanocrystal (NC) conversion chemistry is necessary to access alternative synthetic routes for naturally inaccessible nanostructures and fundamental solutions of any interference impeding their practical applications. For durable catalytic processes and practical energy storage devices, this can enable sustaining full reversibility connecting the active NC components under long, harsh operational conditions. Redox convertible late transition metal oxide (TMO) NCs are excellent anode materials for Li-ion batteries (LIBs) with many superior properties but have deviated from the reversible lithiation/delithiation mechanism (MxOy + 2yLi+ + 2e- xM0/yLi2O). Thus, undesired NC-coalescence and irreversible solid-electrolyte-interphase (SEI) formations result in significant capacity loss with repeated charge/discharge cycles and at high cycling rates (>2.0 C). Several methods, involving immobilization on conductive supports, manipulated crystalline phases, and fabricating hierarchical assemblies, have been investigated to resolve this issue. Sheet-like 2D-TMO nanostructures, which electrochemically convert to reduced metal NC-arrays in 2D-geometry, have proven effective at improving reversible and cycling anode performance at moderate current density ranges (0.2 ~ 1.0 C). However, for practical LIB devices, an increased storage performance, especially at quick charging conditions (> 3.0 C), is required, which may be realized through optimizing 2D-TMOs for improved conversion reversibility. However, as the attempted 2D-TMOs have rough thickness uniformity mostly in the 10 ~ 100 nm range long with the lateral size above 250 nm and often fabricated in the carbon-hybrid form, precise interpretation of thickness-dependent effects of 2D-TMO electrodes, especially within a few-nm-thick range, is still unaccomplished. Hence, we attempted fabrication of thinner 2D-TMOs with well-controlled uniform few-nm thicknesses and assess their effectiveness as LIB anodes based on transformation behavior under redox-switching conditions. The confinement of in-situ created NCs inside the few-nm-thin 2D-nanospace, as pre-defined by the thickness of initial 2D-TMO, would hinder free movement, agglomeration, and sintering of included NCs during their phase transition, improving conversion reversibility. The use of atomic-thin 2D-TMOs was envisioned to place single laterally aligned NC arrays at the ultrathin 2D nanogap, ensuring fully reversible interconversion between reactive NC redox-pairs. However, atomic-thin 2D nanosheets of late TMOs, which are intrinsically non-layered materials, remain a synthetic challenge under conventional methods.Herein, we adopted the nanospace confinement strategy to thermally transform delaminated layered double hydroxides (NiCo-LDH) within a 2D-SiO2 envelope, forming isomorphic 2D-TMOs (Ni3Co1Ox, NCOs) of uniform 1 nm and 7 nm thicknesses from LDH precursors. A thermal conversion study of the 2D-TMOs under the 2D-SiO2-shell protection, as well as an electrochemical investigation within the in-situ formed 2D SEI-envelope identified a substantial confinement effect on sustaining the fully cyclic transformation behavior of the derived NC arrays from 1 nm-thin 2D-TMOs. Thus, the atomic-thin 2D-TMO anode demonstrated highly reversible capacity of 848.36 mAh g-1 at the first cycle and a high-rate capability (a specific capacity of 61.2% at 5.0 C relative to 0.2 C) and, the long-term stable Li-ion storage capacity delivered 1169 mAh g-1 and 913 mAh g-1 of specific capacity during 1000 cycles even at rapid charge/discharge conditions of 3.0 C and 5.0 C rates, respectively.

Binderless Sheet-Type Oxide-Sulfide Composite Solid Electrolyte for All-Solid-State Batteries

Lithium-ion batteries have been used as energy sources not only for small electronic devices but also for high-capacity and high-energy-density applications such as electric vehicles. However, the use of flammable organic liquid electrolytes in lithium-ion batteries has raised safety concerns in various applications. Therefore, solid-state batteries using flame-retardant inorganic materials are considered a more reasonable direction for future energy sources due to their high safety and high energy density. Solid electrolytes(SEs) are divided into oxide-based, sulfide-based, and polymer-based. Each solid electrolyte has its own advantages and disadvantages. Oxide-based solid electrolytes (e.g., Li7La3Zr2O12 (LLZO), Li3xLa2/3-xTiO3 (LLTO), Li1.3Al0.3Ti1.7(PO4)3 (LATP)) are air-stable and exhibit excellent electrochemical properties over a wide potential range. However, their high interfacial resistance may limit their practical application as batteries. Sulfide-based solid electrolytes (e.g., Li6PS5X (X=Cl, Br, I), Li10GeP2S12, (100-x)Li2S-xP2S5)) have high ionic conductivity, ductile properties, low interfacial resistance, and good room temperature workability. However, they are vulnerable to atmospheric instability, which can produce toxic gases such as H2S, and are relatively electrochemically unstable with Li metal. Polymer-based solid electrolytes, such as those made from polymers like PEO, PVDF, PAN, etc. that are compounded with other solid electrolytes (oxides, sulfides, etc.), offer the advantage of being able to form solid electrolyte membranes over large areas. But they have low ionic conductivity and weak mechanical properties of the polymer itself, limiting their practical application. To apply solid-state batteries to practical high-energy density energy storage devices such as electric vehicles, high ion conductivity, electrochemical stability, high mechanical properties, and large area formation of the electrolyte layer are essential. Solid electrolytes are mainly formed in powder form, and without a polymer binder, it is limited to apply as a film for large-capacity storage devices. Here, we fabricated a freestanding sheet-type Al-LLZO oxide-based solid electrolyte that forms a 3D network without a polymer material using an electrospinning method. In addition, we prepared a oxide-sulfide composite solid electrolyte membrane by impregnating LPSCl sulfide-based solid electrolyte into the Al-LLZO solid electrolyte sheet. As a result, This process removed the polymer and improved both the ionic conductivity and mechanical properties. Furthermore, it was possible to achieve both large-area and film characteristics without the need for a polymer.

Unveiling the electrochemical characteristics of acetonitrile-catholyte-based Na-CO2 battery

The development of metal-CO2 batteries has attracted intense attention because of their unique electrochemical reaction for utilization of CO2 gas. However, unlike the alkali metal-based O2 batteries, a limited number of combinations of aprotic electrolytes have been employed for Li(Na)–CO2 batteries due to the sluggish reaction for the formation of the Li(Na)2CO3 discharge product. Here, we demonstrate an acetonitrile (MeCN)-based catholyte for use in a hybrid cell type Na-CO2 battery. The presence of a solid ceramic separator in our hybrid cell allows the stable operation of the MeCN catholyte-based Na-CO2 battery, resulting in improved electrochemical characteristics such as low overpotential, high energy density, and long cycle stability compared to the conventional TEGDME-based electrolyte. In particular, results of molecular dynamics simulations suggest that the improved performance is mainly due to the enhanced Na+ diffusion in the electrolyte. The calculated barrier for Na+ diffusion in MeCN is approximately four times lower than that in TEGDME. Thus, this work provides a promising electrolyte combination and reveals the mechanism for the improved performance of the MeCN-based electrolyte used in the hybrid cell structure, promoting the development of Na-CO2 batteries as practical secondary energy storage devices.

Synthesis and characterization of CoMn2O4 spinel onto flexible stainless-steel mesh for supercapacitor application

CoMn2O4 spinel was synthesized on stainless steel mesh through a hydrothermal process, controlling the reaction time (6 h, 12 h, 18 h, and 24 h). Characterization techniques included XRD, ATR-FTIR, XPS, and SEM-EDS. The 24-h reaction time led to CoMn2O4 spinel with the desired structure, stoichiometry, and good crystallinity. The sample exhibited a tetragonal structure, with Co–O and Mn–O vibrational bands, and manganese (Mn3+) and cobalt (Co2+) metal oxides on the surface. It had a sheet-like shape with an average particle size of 1.92 ± 0.28 μm. Electrochemical tests showed high CV-specific capacitance of 1014.15 F g−1 at 1 mV s−1 and 764.84 F g−1 at 5 mV s−1, aligned with GCD-specific capacitance at 5 A g−1 (724.61 F g−1) and a charge-transfer resistance of 7.71 Ω. The synthesized electrode holds promise for practical energy storage devices, namely for supercapacitor applications.

A flexible asymmetric supercapacitor with organohydrogel electrolyte for high voltage operation over wide temperature range

It is highly desirable for supercapacitors to achieve mechanical flexibility and temperature tolerance, as well as high energy density, to fully utilize their superior characteristics of high-power density and long cycle stability to realize their potential as practical wearable energy storage devices. We devise a novel strategy to fabricate a flexible asymmetric supercapacitor based on dual network organohydrogel, exhibiting high energy density and electrochemical stability over a wide temperature range spanning 100 ℃.A three-dimensional core–shell NiCo2O4@MnO2 nanostructure is selected as the positive electrode to supply multiple ion diffusion channels through its mesoporous structure, and nano structured N-doped carbon nanofibers as the negative electrode to increase the contact area with electrolyte, and 6 M KOH based organohydrogel as electrolyte. The resulting supercapacitor exhibits high electrochemical performance including a high operation voltage of 1.7 V and high energy density of 51.1 Wh kg−1 at a power density of 850 W kg−1 and is stable over temperature changes between –20 and 80 ℃. This work demonstrates a high-performance supercapacitor designed with 3D asymmetric electrodes and a dual network organohydrogel, suitable as a practical energy storage device, requiring mechanical stability and stability against temperature change.

Anthraquinone‐Functionalized Polydiacetylene Supercapacitors

AbstractOrganic supercapacitors are considered attractive alternatives to traditional inorganic‐based charge storage devices due to their synthetic versatility, low cost, and environment‐friendliness features. Photopolymerized anthraquinone‐polydiacetylene is employed as a core component in high‐performance asymmetric supercapacitors (ASCs). Specifically, interspersed polydiacetylene‐anthraquinone/polyaniline (PANI) electrodes are prepared via drop‐casting and used as cathodes in devices employing polypyrrole/reduced graphene oxide anodes using aqueous or ionic liquid electrolytes. The excellent electrochemical properties of the polydiacetylene‐anthraquinone/PANI electrodes, specifically high capacitance (specific capacitance ≈720 F g−1 at 1 A g−1), long discharge time, and cycling stability, are ascribed to the superior redox profile of the anthraquinone and ambipolar charge transport associated with the polydiacetylene framework. The asymmetric supercapacitor prepared using the polydiacetylene‐anthraquinone/PANI electrodes displays a high energy density of 36 Wh kg−1 at a power density of 995 W kg−1, underscoring possible utilization of the anthraquinone‐polydiacetylene derivative in practical energy storage devices.

Experimental Analysis of Charging and Discharging Characteristics of Sensible Energy Storage System

Abstract: To meet energy needs in the absence of an energy source, practical energy storage devices can be combined with home and industrial systems. The thermal properties of a practical energy storage system with numerous cylindrical channels are investigated in this work experimentally during the charging and discharging cycles. By adjusting the mass flowrate of air from 0.022 to 0.031 kg/s and the input air temperature from 45 to 75 °C, the transient temperature distribution, energy storage, energy release, and charging/discharging energy efficiency are assessed. At an intake temperature of 55 °C and an air mass flowrate of 0.031 kg/s, the maximum charging energy efficiency of 81.3% was discovered. The maximum discharging energy efficiency is discovered to be 74.3%, which corresponds to an air mass flowrate of 0.031 kg/s and an inlet temperature of 45 °C.

Oxygen-Related Defect Engineering of Amorphous Vanadium Pentoxide Cathode for Achieving High-Performance Thin-Film Aqueous Zinc-Ion Batteries

Thin-film aqueous zinc-ion batteries are expected to serve as next-generation energy storage devices that are both low-cost and safe. However, to realize practical energy storage devices based on zinc-ion batteries, it is necessary to develop reliable, high-capacity cathode materials. In this study, we prepared a V2O5-based thin-film electrode and investigated the effect of varying the Ar pressure during radio frequency magnetron sputtering of V2O5, a representative cathode material in thin-film zinc-ion batteries, to control the number of oxygen vacancies in the oxide lattice. The optimized V2O5 thin-film electrode exhibited enhanced electrochemical activities, low degree of polarization, improved ion diffusion, and increased electrical conductivities. Specifically, an oxygen-deficient V2O5–x thin-film prepared by sputtering under high pressure exhibited a high rate capability (57.2 mAh g–1 at 20 C) and superior electrochemical performance (105.2 mAh g–1 for up to 1000 cycles at a current density of 5 C). The mechanism for the performance enhancement was revealed by density functional theory calculations, which showed that the oxygen-deficient V2O5–x had a lower Zn2+-ion diffusion energy barrier than that of pristine V2O5. This defect engineering strategy for tuning the oxidation state should aid in designing high-performance cathodes for advanced thin-film aqueous battery chemistry.

Carbon-Shielded Selenium-Rich Trimetallic Selenides as Advanced Electrode Material for Durable Li-Ion Batteries and Supercapacitors.

In order to achieve a sustainable future, researchers must continue to research improved electrode materials. Considering the high electronic conductivity, versatile redox activity, and enhanced energy storage performance, nanostructures have been employed as a novel electrode material for high-performance lithium-ion batteries (LIBs) and supercapacitors. Herein, carbon-coated selenium-rich trimetallic selenide (Cu2 NiSnSe4 @C) nanoparticles (NPs) as an efficient electrode material in energy storage devices are prepared. The prepared core-shell Cu2 NiSnSe4 @C NPs electrode is employed as ananode material for LIBs, which demonstrated a high reversible specific capacity of 988.46mA h g-1 over 100 cycles at 0.1 A g-1 with good rate capability. Additionally, the core-shell Cu2 NiSnSe4 @C NPs electrode exhibited an outstanding capacity of 202.5mA h g-1 at 5 A g-1 even after 10 000 cycles. Exploiting the synergistic characteristics, the core-shell Cu2 NiSnSe4 @C NPs material is also investigated as a battery-type electrode for hybrid supercapacitors. The assembled hybrid supercapacitor with Cu2 NiSnSe4 @C NPs and activated carbon showed excellent rate capability including high power (5597.77W kg-1 ) and energy (64.26Wh kg-1 ) densities. Considering the simple synthesis and enhanced energy storage properties, carbon-coated selenium-rich trimetallic selenide can be used as a durable electrode material for practical energy storage devices.

Metal Phosphates: Emerging Materials for Energy Storage

In recent years metal phosphates have gained the limelight due to their unique properties and versatile electrochemical behaviour. These materials offer a wide range of compositions, crystal structures, and redox properties, enabling their application in various energy storage systems. This review provides an overview of the recent advancements in metal phosphates for energy storage, focusing on their synthesis, electrochemical performance, and potential applications. Metal phosphates hold great promise as emerging materials for energy storage applications. Their tunable properties, versatile electrochemical behaviour, and potential for multiple energy storage systems make them potential candidates for nextgeneration energy storage technologies. Ongoing research and development efforts are crucial to revealing the full potential of metal phosphates and accelerating their integration into practical energy storage devices

Halogen-regulating induced reversible high-temperature dielectric and thermal transitions in novel layered organic-inorganic hybrid semiconducting crystals.

Organic-inorganic hybrid metal halides for high-temperature phase transition have become increasingly popular owing to their wide operating temperature range in practical applications, e.g., energy storage, permittivity switches and opto-electronic devices. This paper describes the subtle assembly of two new hybrid perovskite crystals, [Cl-C6H4-(CH2)2NH3]2CdX4 (X = Br 1; Cl 2), undergoing high-T reversible phase transformations around 335 K/356 K. Differential scanning calorimetry (DSC), differential thermal analysis (DTA) and VT PXRD tests uncover their reversible first-order phase transition behaviors. Furthermore, the compounds exhibit switchable dielectricity near T, making them potential dielectric switching materials. Hirshfeld surface analysis well discloses a distinct difference in hydrogen-bonding interaction between 1 and 2. UV spectra and computational analysis demonstrate that the compounds are a type of direct-band-gap semiconductor. This research will contribute an effective approach to the structure and development of multifunctional molecular hybrid crystals.

Cobalt pentlandite structured (Fe,Co,Ni)9S8: Fundamental insight and evaluation of hybrid supercapacitor

From the perspective of improving energy density, research efforts to design electrode materials that can be used in supercapacitors based on mature transition metal sulfides are already so common and efficient but insufficient. So it is a nice approach to empower the traditional transition metal sulfides with new vitality by composite structures to enrich the family of metal sulfides. In this study, we synthesized a kind of cobalt pentlandite structured (Fe,Co,Ni)9S8 originally existed only in natural ores by relatively mild means, and found that such structured materials have good potential for use in supercapacitors. The optimized (Fe,Co,Ni)9S8 sample presents a remarkably high specific capacity of 135 mAh/g at 1 A/g as well as favorable cycling stability. Density functional theory simulations confirmed the metallic properties of such sample, and Co sites are more favorable for the adsorption of OH–. Moreover, a button-type hybrid supercapacitor was fabricated utilizing our designed electrode material, presenting a relatively high energy density of 50 Wh kg−1 at 1353 W kg−1 and good cyclic stability. Moreover, two such hybrid supercapacitors can power a red LED for 22 min, which has shown its attractive and promising possibilities for practical energy storage devices.

Recent Developments of Inkjet‐Printed Flexible Energy Storage Devices

AbstractWith the rapid development of portable and wearable electronics, the design and fabrication of flexible electrochemical energy storage devices, including batteries and supercapacitors, have attracted tremendous attention among both scientific and industrial fields. Inkjet printing is considered to be a promising technology for manufacturing low‐cost high‐performance flexible energy storage devices because of its material‐saving feature and pattern‐writing flexibility. Very recently, great efforts have been dedicated to adapting inkjet printing for the production of practical flexible energy storage devices. In this review, inkjet printing operation mechanisms, ink properties, and the interaction between the droplet and substrate are first described in detail. Then the development of inkjet‐printed flexible electrochemical energy storage devices in recent years is focused on from the perspective of electrode materials. Next, the application of inkjet‐printed flexible energy storage devices in self‐powered electronic systems is briefly introduced. At last, challenges and future development directions of inkjet‐printed flexible energy storage devices are further discussed.

Kinetics-favorable heterojunctional CNTs@CuCo-LDH/BPQD electrode with boosted charge storage capability for supercapacitor

Component modulation and structure construction are the fundamental strategies in designing electrode materials for supercapacitors. Layered double hydroxide (LDH) is considered the promising electrode material, while with the drawback of low electron transmission efficiency and pulverization hinder. Herein, a novel kinetics-favorable heterojunctional self-supporting film electrode, composed of carbon nanotubes (CNTs), CuCo-LDH, and black phosphorus quantum dots (BPQD), is successfully prepared and directly utilized as electrodes in the supercapacitor. Highly conductive CNTs evenly and heavily entangled with CuCo-LDH hollow structures, resulting in robust mechanical property, enhanced electrical conductivity, and accelerated charge transfer during a redox reaction. Together with the surface decorated high-carrier-mobility BPQD, constructing heterojunction and acting as an electron donor to provide numerous active sites and facilitate energy storage behavior, a promoted pseudocapacitive performance was obtained and furtherly demonstrated by the density functional theory simulations based on the adsorption energies of OH–. The as-fabricated CNTs@CuCo-LDH/BPQD electrode presents a maximum capacitance of 1061.6 F g−1. The as-assembled hybrid supercapacitor device represents energy density up to 62.1 Wh kg−1 and remarkable cycling performance with 79.1% capacity retention after 10,000 cyclic tests. The prototype supercapacitor of this work shed light on the engineering of LDH-based materials for practical energy storage devices.

Dual-engineering of ammonium vanadate for enhanced aqueous and quasi-solid-state zinc ion batteries

Ammonium vanadate holds promise for the high-performance cathode in aqueous zinc ion batteries (ZIBs) due to its stable layered structure and superior theoretical capacity. However, excessive ammonium cations occupying the interlayer and too strong electrostatic interaction between Zn2+ and defect-free V-O bonds largely hinder the capacity and rate performance of ammonium vanadate in ZIBs. Here, in this work, a dual-engineering method that integrates the partial removal of ammonium cations and the increase of oxygen vacancies has been proposed to boost the performance of NH4V4O10 (NVO). Experimental evidence and theoretical calculations demonstrate that this method can ensure an enlarged room for the (de)intercalation of more Zn2+ ions and weaken the strong electrostatic interaction between the V-O layer and Zn2+ to reduce the energy barrier of the Zn2+ diffusion process. As a consequence, the specific capacity of the as-obtained NVO with the above dual characteristic (NVO-300) was enhanced from 304 mAh g−1 to 355 mAh g−1, relative to the NVO without dual characteristic. And the rate capability of NVO-300 has a more than 300% increase relative to NVO. Furthermore, benefiting from the superior performance and self-supporting feature of this NVO-300, a quasi-solid-state ZIB based on NVO-300 displays a satisfactory specific capacity of 307 mAh g−1 at 0.5 A g−1 and a high energy density of 214 Wh kg−1 at 345 W kg−1, demonstrative of its great usage potential as a practical portable energy storage device.

(Invited, Digital Presentation) Multiscale Measurements and Characterization of Thermal Transport in Materials and across Interfaces in Li-Ion Cells

Li-ion cells are used universally for energy conversion and storage. Key application areas include electric vehicles, grid energy storage, air/space vehicles and consumer electronics. Overheating of Li-ion cells is a well-known problem, with serious concerns related to thermal runaway and fire. Additionally, Li-ion cells also under-perform at low temperatures, which is a particularly important problem for automotive and space applications. Advances in battery materials are needed to mitigate these concerns and improve the performance and safety of Li-ion cells. This talk will summarize research advances in understanding and optimizing thermal transport in Li-ion cell and battery pack materials. Measurement of thermal conductivity of cylindrical Li-ion cells, indicating the highly anisotropic nature of thermal conduction will be described. This will be followed by discussion of measurement of thermal properties of individual cell materials, such as the separator, as well as thermal contact resistance at the cathode-separator interface. This contact resistance will be shown to play a rate-limiting role in determining overall thermal transport properties of the cell, and is, in particular, responsible for anisotropic thermal conduction. Experiments to mitigate this thermal resistance through molecular bridging at the interface will be described. Good agreement with molecular dynamics simulations will be demonstrated. Challenges associated with practical implementation of such techniques will be discussed. Finally, numerical simulations to understand the nature of thermal transport in battery packs will be described, with the goal of minimizing thermal runaway propagation. These measurements and modeling techniques contribute towards a fundamental understanding of multiscale thermal transport in Li-ion cell materials, and may help optimize and improve thermal performance of practical energy conversion and storage devices.

Ti3C2TxMXenes-based flexible materials for electrochemical energy storage and solar energy conversion

AbstractOver the past decade, two-dimensional (2D) Ti3C2TxMXenes demonstrated attractive characteristics such as high electrical conductivity, tunable layered structure, controllable interfacial chemical composition, high optical transparency, and excellent electromagnetic wave absorption, enabling Ti3C2TxMXenes as promising electrode materials in energy storage devices. Among these devices, flexible energy storage devices have attracted wide attention and developed rapidly due to the synchronously excellent electrochemical and mechanical properties. This review summarizes the recent progress of Ti3C2TxMXenes pertaining to novel material preparation and promising applications in energy storage and conversion including batteries, supercapacitors, solar cells, and solar steam generation. This work aims to provide an in-depth and reasonable understanding of the relationship between the unique nanostructure/chemical composition of Ti3C2TxMXenes and competitive electrochemical properties, which will facilitate the development of 2D Ti3C2TxMXenes for practical energy storage and solar energy conversion devices.