Attention In Energy Storage Devices Research Articles

Oxygen‐Poor Amorphous Heterostructure Derived from Nb2CTx Toward Superior Lithium‐Ion Storage

AbstractDue to the long‐range atomic disorder and more active sites, amorphous MXenes with better chemical reactivity and electrical conductivity, have attracted wide attention in energy storage devices. However, to reach the practical applications of MXenes, investigations into the best structure of the amorphous layer are essential. Here, the structure evolution of MXenes induced from ammonium persulfate is explored via synchrotron radiation X‐ray absorption spectroscopy. Then, a kind of oxygen‐poor amorphous heterojunction Nb2CTx MXene (a‐Nb2CTx) is designed. Benefitting from the oxygen‐poor amorphous heterojunction, the a‐Nb2CTx electrode exhibits excellent Li+ storage performance with a high discharge specific capacity of 382 mAh g−1 at 0.1 A g−1 and a long cycling stability of 300 mAh g−1 at 1.0 A g−1 after 800 cycles. Operando synchrotron X‐ray diffraction results reveal that oxygen‐poor amorphous heterojunction stabilizes Nb2CTx MXene from undergoing structural changes during cycling. This work provides new insights into the rational design of novel amorphous MXenes, which is of great significance for the development of MXenes and their applications in high‐performance energy storage systems.

Ultrafast Hole Migration at the p-n Heterojunction of One-Dimensional SnS Nanorods and Zero-Dimensional CdS Quantum Dots.

The p-n heterojunctions fabricated from one-dimensional (1D) p-type tin sulfide nanorods (SnS NRs) decorated with n-type zero-dimensional (0D) cadmium sulfide quantum dots (CdS QDs) have gained significant research attention in energy storage devices. Herein, we have successfully synthesized a 1D/0D SnS@CdS heterostructure (HS) using a hot injection method. Structural and morphological studies clearly suggest that CdS QDs are uniformly anchored on the surface of SnS NRs, resulting in intimate contact between two components. The photoluminescence (PL) study revealed the transfer of photoexcited holes from CdS QDs to SnS NRs, which was further confirmed by transient absorption (TA) studies. TA measurements demonstrate the hole transfer from the valence band of CdS QDs to SnS NRs and delocalization of electrons between the conduction band of SnS NRs and CdS QDs in SnS@CdS HS, resulting in efficient charge separation across the p-n heterojunction. These findings will open up a new paradigm for improving the efficiency of optoelectronic devices.

Interconnected Vanadyl Pyrophosphate Nanonetworks as a Flexible Electrode for High-Voltage and Long-Life Li-Ion Supercapacitors.

Engineering vanadium-based materials with high conductivity, superior redox performance, and high operating voltage has attracted widespread attention in energy storage devices. Herein, we demonstrated a simple and feasible phosphorization technique to design three-dimensional (3D) network-like vanadyl pyrophosphate ((VO)2P2O7) nanowires on flexible carbon cloth (CC) (VP-CC). The phosphorization process enabled the VP-CC to increase the electronic conductivity, and the interconnected nano-network of VP-CC opens pathways for fast charge storage during the energy storage processes. Specifically, the 3D VP-CC electrodes and LiClO4 electrolyte designed as a Li-ion supercapacitor (LSC) demonstrate a maximum operating window of 2.0 V with a superior energy density (Ed) of 96 μWh cm-2, power density (Pd) of 10,028 μW cm-2, and outstanding cycling retention (98%) even after 10,000 cycles. In addition, a flexible LSC assembled utilizing VP-CC electrodes with a PVA/Li-based solid-state gel electrolyte exhibits a high capacitance value of 137 mF cm-2 and excellent cycling durability (86%) with a high Ed of 27 μWh cm-2 and Pd of 7237 μW cm-2. Considering excellent energy storage features, the highly conductive vanadium-based material has been utilized as an ideal electrode for various flexible/wearable energy storage devices with superior performance.

First principles study of the structural, mechanical and optical properties of Li6PS5X (X= Cl, I) argyrodite compounds

Phosphorus-containing argyrodite are now gaining high attention for energy storage devices. Here, the electronic, structural, optical and elastic properties of Li6PS5X (X = Cl, I) argyrodites by utilizing density functional theory (DFT) have been studied. Trans-Blaha approach of the modified Becke–Johnson (TB-mBJ) potential is used to get accurate band gap energy values where the (PBEsol-GGA) are used for the calculations of the structural parameters of Li6PS5Cl and Li6PS5I compounds with lattice parameters of 10.31 Å and 10.36 Å respectively. The mBJ-functional shows energy bandgap of Li6PS5Cl to be 3.11 eV and for Li6PS5I with band gap of 2.81 eV. The static refractive index for Li6PS5Cl and Li6PS5I are 2.23 and 1.90. Elastic constants of the cubic compounds C11, C12 and C44 and different moduli like Young modulus, Shear moduli alongwith different parameters like Kleinman's parameters, first and second Lame constants, Hardness, Melting temperature, Chung-Buessem anisotropy index, universal anisotropic index, acoustic behavior and its anisotropy, Poisson ratios. Mechanically the compounds determined as brittle. The current study has reported many new results on the argyrodite compounds which maybe interesting for future experimental studies and further theoretical exploration of the family of these compounds.

Metal organic framework-derived MnO@carbon composites for highly durable Li-ion batteries and hybrid electrochemical cells

Exploring structurally stable and high-capacity metal oxides with carbon-based composite have attracted great attention in energy storage devices. Herein, we demonstrate gram scale synthesis of manganese oxide encapsulated carbon (MnO@C) nanofoil composite using the simple thermolysis of manganese metal organic framework (Mn-MOF) under inert atmosphere. The encapsulated MnO nanoparticles on carbon nanofoils enable higher electrochemical conductivity and extended durability as an electrode material for Li-ion batteries and supercapacitors (SCs). Specifically, the prepared MnO@C nanofoil composite delivers a reversible capacity of 1083 mAh g−1 for MnO@C, which is higher than the pristine Mn2O3 (889 mAh g−1) at a current density of 500 mA g−1 after 100 cycles. The MnO@C nanofoil composite also exhibits much better specific capacity of 771 mAh g−1 at a high current density of 2000 mA g−1 with the retention rate of 89% after 800 cycles. Furthermore, as a battery-type electrode for hybrid SCs, the MnO@C nanofoil composite shows higher capacitance and energy/power densities of 46.7 F g−1 and 15.9 Wh kg−1/4356.3 W kg−1 with excellent cycling durability. The cost-effectively synthesized MOF-derived composites could be utilized as promising materials in the development of long-term energy storage devices.

Highly-active CoMn2O4 nanowires decorated with multilayer Ni(OH)2 nanosheets as bind-free electrodes for high-performance energy storage application

Transition metal oxides have obtained considerable research attention in energy storage devices. In this study, we demonstrate the preparation of hierarchical CoMn 2 O 4 @Ni(OH) 2 nanowire arrays (CoMn 2 O 4 @Ni(OH) 2 /Ni) by a combination of hydrothermal reactions and annealing process. This hybrid CoMn 2 O 4 @Ni(OH) 2 /Ni electrode possesses a significantly enhanced capacity of 8.5 F cm −2 at 1 mA cm −2 (3017.9 F g −1 at 0.4 A g −1 ). Additionally, the assembled all-solid-state asymmetric supercapacitor (CoMn 2 O 4 @Ni(OH) 2 /Ni//AC ASC) displays a comparable energy density of 76.2 Wh kg −1 . Meanwhile, the prepared CoMn 2 O 4 @Ni(OH) 2 /Ni anode revealed initial discharge capacity (~3548.2 mAh g −1 ). After 50 cycles, the CoMn 2 O 4 @Ni(OH) 2 /Ni anode also shows a satisfied cycling stability (1437.4 mAh g −1 of capacity maintained). Further, the LED devices can be lit up for more 230 min by the assembled CoMn 2 O 4 @Ni(OH) 2 /Ni cell. Therefore, this novel CoMn 2 O 4 @Ni(OH) 2 /Ni materials with excellent electrochemical property have great potential in the high energy storage applications. • The rough surface of nanowires enhances the binding force with nanosheets and improve the cycling stability. • The ultra-thin Ni(OH) 2 nanosheets can protect the internal CoMn 2 O 4 nanowires and possess large surface area. • The hybrid electrode reveals good electrochemical performance in both supercapacitors and Li ion batteries.

N and S co-doped 3D hierarchical porous carbon as high-performance electrode material for supercapacitors

The use of renewable and environmentally friendly biomass to prepare carbon materials with a hierarchical porous structure and large specific surface area has attracted great attention in energy storage devices (Supercapacitors, SCs). Here, a succulent-leaf-derived carbon material with a hierarchical porous structure (N-S-HPC) was prepared through a one-step carbonization strategy using Mg(NO3)2·6H2O and ZnCl2 as double activation agents and CH4N2S as S and N source. The N-S-HPC specific capacitance reached 455.3 F g−1 at 1 A g−1, and with 1 M Na2SO4 electrolyte. The assembled N-S-HPC//N-S-HPC symmetric SCs could enhance the voltage window to 1.8 V. Meanwhile, N-S-HPC exhibited the specific energy of 19.89 Wh kg−1 (450 W kg−1) and highly stable cycling performance. Compared with previously reported biomass-derived carbon materials, N-S-HPC has the advantages of i) hierarchical porous sturcture and 2136.2 m2 g−1 maximal specific surface area, allowing accommodation of more ions; ii) 1177.5 m2 g−1 specific surface area for mesopores and macropores, providing shorter diffusion pathways; iii) rich co-doping of N (9.5 at.%) and S (2.21 at. %), increasing pseudocapacitive contribution and improving surface wettability. All these data indictae the great potential application prospect of N-S-HPC, suggesting the importance of biomass-derived carbon materials for symmetric SCs.

Rational design of cobalt-iron bimetal layered hydroxide on conductive fabric as a flexible battery-type electrode for enhancing the performance of hybrid supercapacitor

Mixed metal hydroxide (MMH) based supercapacitor electrodes, with their outstanding performance from the synergistic effect originating from mixed metallic elements, can effectively address the drawbacks of single metal hydroxide (SMH) based electrodes. Owing to their superior electrochemical properties stemming from their unique structural and chemical compositional design, MMH electroactive materials have attracted considerable attention for energy storage devices. Among those devices, a layered double hydroxide (LDH) structure has been emerged as an alternative electrode due to its large interlayer arrangement, high redox activity, and multiple oxidation states. Herein, we have successfully designed cobalt-iron LDH nanosheets (CoFe LDH NSs) on nickel fabric by a facile electrochemical deposition (ECD) method with a chronoamperometry voltage of − 1.0 V for 100 s. Further, the unique as-fabricated structure that arises from the tunable chemical composition and wide variety of material properties was successfully manipulated to boost the electrochemical energy storage performance. Finally, the optimized electrode made of Co0.5Fe0.5 exhibited superior electrochemical performance due to its porous, surface-stimulated large electroactive area and high conductivity with great stability. By integrating a battery-type electrode of CoFe LDH and a capacitive-type electrode of activated carbon (AC), a hybrid supercapacitor (HSC) device was assembled. Besides, the high areal capacitance of 70 µF/cm2, it delivers high energy density (1.6 mWh/cm2) and power density (0.09 mW/cm2) values along with the excellent cycling stability (91% capacity retention). Moreover, the fabricated flexible device offers the significance as a power source in flexible electronic devices with its high degree of flexibility originated from flexible substrate. This work not only provides a promising electrode for supercapacitors, but also a unique structural and compositional design of electroactive materials for energy storage systems.

Synchrotron X-ray Spectroscopic Investigations of In-Situ-Formed Alloy Anodes for Magnesium Batteries.

Magnesium batteries present high volumetric energy density and dendrite-free deposition of Mg, drawing wide attention in energy-storage devices. However, their further development remains stagnated due to relevant interfacial issues between the Mg anode and the electrolyte and sluggish solid-state diffusion kinetics of Mg2+ ions. Herein, an in situ conversion chemistry to construct a nanostructured Bi anode from bismuth selenide driven by Li+ is proposed. Through the combination of operando synchrotron X-ray diffraction, ex situ synchrotron X-ray absorption spectroscopy, and comprehensive electrochemical tests, it is demonstrated that the nanosize of the in-situ-formed Bi crystals contributes to the fast Mg2+ diffusion kinetics and highly efficient Mg-Bi alloingy/de-alloying. The resultant Bi anodes exhibit superior long-term cycling stability with over 600 cycles under a high current density of 1.0 A g-1 . This work provides a new approach to construct alloy anode and paves the way for exploring novel electrode materials for magnesium batteries.

Vanadium Disulfide Nanosheets Synthesized by Facile Liquid‐Phase Exfoliation for Ammonia Detection with High Selectivity

AbstractVanadium disulfide (VS2), a typical layered transition‐metal dichalcogenide, has drawn extensive attention in energy storage devices, catalysts as well as sensors due to its intriguing electronic peculiarities, whereas its chemiresistive gas sensing properties have seldom been investigated. In this contribution, first the ammonia sensing properties of VS2 nanosheets (NSs)‐based chemiresistive gas sensor are reported. VS2 NSs are synthesized through facile liquid‐phase exfoliation, and their crystal structure, micromorphology, and elemental component are characterized. Density functional theory calculation has revealed that VS2 (100) is highly affinitive to ammonia molecule, and sufficient electron transfers from ammonia to VS2, which implies VS2 NSs possess high potential for ammonia sensing. The computational results are verified by gas sensing measurement that the resistance of VS2 NSs remarkably increases upon injecting ammonia gas at low working temperature of 40 °C. Additionally, the VS2 NSs exhibit superb selectivity to ammonia. The probable mechanism for ammonia sensing can be that ammonia molecule absorbed at edge sites of VS2 NSs transfers electron to p‐type VS2 NSs, reduces hole concentration in the NSs, and thus leads to resistance enhancement of VS2 NSs.

Self-supported nickel cobalt carbonate hydroxide nanowires encapsulated cathodically expanded graphite paper for supercapacitor electrodes

The self-standing electrode materials with large surface area and high electronic conductivity have attracted intensive attention in energy storage devices. Herein, the expanded graphite paper (EGP) is fabricated via a controlled cathodic expansion in acetonitrile with tetrabutylammonium bromide at 10 V. The as-prepared EGP exhibits a three-dimensional porous structure with large specific surface area and high electronic conductivity, which is a favorable support for in situ growing nickel cobalt carbonate hydroxide (NiCo-CH) nanowires via a simple hydrothermal method. The as-prepared NiCo-CH@EGP composite achieves high areal capacity of 2.55 C cm−2 at 0.5 mA cm−2, and still remains 1.38 C cm−2 even at 60 mA cm−2. The assembled NiCo-CH@EGP//activated carbon asymmetric supercapacitor exhibits the maximum energy density of 0.30 mWh cm−2 at a power density of 0.92 mW cm−2, and a suitable cyclic stability with the capacity retention of 78.1 % after 10,000 cycles at 20 mA cm−2. The results indicate that the self-standing NiCo-CH@EGP is a potential electrode material for energy storage devices.

Activated Carbon Monolith Derived from Coconut Husk Fiber as Electrode Material for Supercapacitor Energy Storage

Biomass-derived porous activated carbon materials have been receiving considerable attention in energy-storage devices especially for supercapacitor due to abundant, renewable, sustainable, and cost-effective production. In this study, porous activated carbon material with monolithic form has been successfully prepared from coconut husk fiber through one-stage integrated pyrolysis and ZnCl2 impregnation. Different physical activation temperature is the main focus in this study including 750, 800, 850, and 900 °C. The reduction of monolith dimensions such as mass, diameter, thickness and density have been reviewed as physical properties. Furthermore, the supercapacitor cells were performed with cyclic voltammetry t 1 M H2SO4 aqueous electrolyte at low scan rate of 1 mV s−1. The supercapacitor device based on the CFM-800 samples exhibited highest specific capacitance of 216 F g−1. This sample also performed a promising performance with an energy density of 30.00 Whkg−1 and a high power density of 108.57 Wkg−1. These results demonstrate that the coconut husk fiberhas been a high potential to as raw material for porous activated carbon monolith through low cost, vehicle and short-time processing with high-performance supercapacitors energy storage.

Biomass-derived porous carbon electrodes for high-performance supercapacitors

Biomass-derived porous carbon materials have been receiving considerable attention in energy-storage devices by virtue of the abundant and renewable sources. In this work, we developed a facile, yet scalable fabrication of nitrogen doping porous carbon (QPC-3) with high specific surface area (SSA) of 2597 m2 g−1 derived from quinoa. The QPC-3 electrode exhibits a special capacitance of 330 F g−1 in 6 M KOH at a density of 1 A g−1 and a good rate capability. Additionally, symmetrical supercapacitors assembled by QPC-3 can deliver capacitances of 254 F g−1 and 99.2 F g−1 at 0.5 A g−1, and the energy densities approach 9.5 Wh kg−1 and 22 Wh kg−1 in aqueous and organic electrolyte, respectively. The results suggest that this quinoa-derived porous carbon could be a promising biomass-derived electrode material applied in high-capacitance supercapacitors.

In-situ temperature regulation of flexible supercapacitors by designing intelligent electrode with microencapsulated phase change materials

Benefiting from the on-going update of wearable electrical devices, flexible supercapacitors have attracted extensive attention in energy storage devices. However, the challenge still exists in achieving high electrochemical performance and cycling stability at high operating temperatures. Herein, an innovative in-situ thermal management system by rationally implanting microencapsulated phase change materials (MPCMs) into three-dimensional porous reduced graphene oxide/polyaniline (GP) frameworks on the surface of carbon nanotube film (CNF) was developed for flexible all-solid-state supercapacitors via facile one-pot electrochemical co-deposition method. The flexible sandwich-shaped all-solid-state supercapacitors using hybrid CNF/GP/MPCMs as electrodes and PVA-H2SO4 as the gel electrolyte were successfully assembled. The incorporation of MPCMs effectively suppressed the temperature fluctuation of the supercapacitor and promoted its operation stability at high temperatures. The supercapacitor containing MPCMs showed superior long-term cyclic stability in comparison with the counterpart without MPCMs. Moreover, the as-prepared supercapacitor was capable of enduring deformations of various angles and maintained 94.1% of the initial capacitance after 500 bending cycles, manifesting excellent mechanical performance. The study paves a feasible way of facilely constructing temperature regulation mechanism based on MPCMs for flexible high-performance supercapacitors.

Polyoxometalates-Based Metal-Organic Frameworks Made by Electrodeposition and Carbonization Methods as Cathodes and Anodes for Asymmetric Supercapacitors.

Hybrid materials have obtained well-deserved attention for energy storage devices, because they show high capacitances and high energy densities induced by the synergistic effect between complementary components. Polyoxometalate-based metal-organic frameworks (POMOFs) possess the abundant redox-active sites and ordered structures of polyoxometalates (POMs) and metal-organic frameworks (MOFs), respectively. Here, an asymmetric supercapacitor (ASC) NENU-5/PPy/60//FeMo/C was fabricated in which both its electrodes are prepared from POMOF precursors. A typical POMOF material, NENU-5, was first connected with polypyrrole (PPy) through electrodeposition to form the cathode material NENU-5/PPy. Another representative POMOFs material, PMo12 @MIL-100, was carbonized to obtain the anode material FeMo/C. Cathode NENU-5/PPy exhibited an extraordinary capacitance of 508.62 F g-1 (areal capacitance: 2034.51 mF cm-2 ). In addition, anode FeMo/C shows excellent cyclic stability attributed to its unique structure. Finally, benefiting from the outstanding capacitances and structural merits of the anode and cathode, assembled asymmetric supercapacitor NENU-5/PPy/60//FeMo/C achieves an energy density of 1.12 mWh cm-3 at a power density output of 27.78 mW cm-3 , as well as a notable life of 10 000 cycles with an capacity retention of 80.62 %. Thus, the unique ASC is strongly competitive in high capacitance, long cycle life, and high energy-required energy storage devices.