Ultrahigh Specific Capacitance Research Articles

Designing electron/ion dual-phase conductor Ni@TiO2 for high-performance lithium-ion storage: Combining insertion and space charge mechanism

In this study, we construct an yolk-shell Ni@TiO2 nanosphere to investigate its performance in lithium-ion batteries. The composite possesses a synergistic storage mode consisting of a Li+-accepting and an electron-accepting phase. Used as an anode material, it delivers ultra-high specific capacity with excellent rate performance and cycling stability. In situ magnetic characterization and thermodynamic simulation reveal the existence of space charge storage mechanism. We propose an overall view on the Li storage mechanism of the Ni@TiO2 and demonstrate the importance of space charge storage for performance improvement in Li-ion batteries.

DFT insights into the adsorption mechanisms of lithium polysulfides on Ni2P (0001) surface for lithium–sulfur batteries

Reliable and sustainable energy storage systems are crucial for a renewable energy future. The ultrahigh theoretical specific capacity and energy density of lithium–sulfur batteries (LSBs) make them one of the most promising next-generation battery technologies. However, their large-scale applications are seriously limited by rapid capacity fading and poor Coulombic efficiency owing to the shuttling of lithium polysulfides (LiPSs). Herein, we investigate nickel phosphide (Ni2P) as an effective host material to realize high-performance LSBs based on first-principles density functional theory (DFT) calculations. Our calculated adsorption energies of the LiPSs species reveal that the Ni2P(0001) surface possesses moderate to high adsorption strength and the adsorption process is facilitated via charge transfer from the LiPSs to the interacting Ni2P(0001) surface atoms. Due to the strong interactions between Ni2P(0001) and LiPSs (Li2Sx, x = 1, 2, 4, 6 and 8), we observe elongation of the intramolecular Li–S bonds in LiPSs upon their adsorption. The stronger adsorption of Li2S coupled with its spontaneous dissociation suggests a faster charging process could occur on the on Ni2P(0001) surface. These results demonstrate that Ni2P can provide effective anchoring sites for the soluble LiPSs, potentially having implications for the design of electrodes for practical LSBs.

Enhancing air stability of LiMg alloy anode through Yb segregation at grain boundaries

Owing to the ultrahigh theoretical specific capacity and the most negative electrochemical potential, lithium metal has become the most promising lithium battery anode material. However, it is highly susceptible to oxidation during industrial production and storage processes. The polycrystal surface of the lithium metal anode serves as the site for oxidation reaction, and the reaction pathway is inevitably influenced by the microstructure of the anode surface. especially the grain boundaries, which with higher activity than a crystallographic plane, leading to intercrystalline oxidation reactions. Within the LiMg@Yb alloy system, ytterbium (Yb) segregated at the grain boundaries, leading to a reduction in intercrystalline energy as predicted by Density Functional Theory (DFT) calculations. Thus, the LiMg@Yb alloy can effectively suppress intercrystalline oxidation reactions and enhance air stability. More impressively, even exposed to ambient air for 0.5 h, the LiMg@Yb-0.5||LFP full cell exhibited a higher capacity retention rate (80.7%) than the bare Li-0.5||LFP (35.9%) after 100 cycles. This work presents a new approach for enhancing air stability by inhibiting intercrystalline oxidation reactions between anodes and air.

Petaloid bimetallic metal-organic frameworks derived ZnCo2O4/ZnO nanosheets enabled intermittent lithiophilic model for dendrite-free lithium metal anode

The application of lithium metal anode (LMA) is hindered by its poor cycle life which could be caused by lithium dendrite and critical volume change during cycling. Our group previously proposed an intermittent lithiophilic model for three-dimensional (3D) composite LMA, however, the lithium electrodeposition behavior was not discussed. To verify this model, this work proposed a facile design of a petaloid bimetallic metal–organic frameworks (MOFs) derived ZnCo2O4/ZnO (ZZCO) nanosheets modified carbon cloth (CC), i.e. CC@ZZCO, as a 3D host to achieve the intermittent deposition of lithium (Li). The material characterizations, density functional theory (DFT) calculations, lithium electrodeposition behaviors, and the electrochemical tests were investigated and the intermittent lithium deposition behavior was firstly confirmed. Thanks to the intermittent lithiophilic model, the composite LMA enabled a prolonged lifespan of 1500 h in a symmetrical cell under challenging conditions of 5 mA h cm−2 and 5 mA cm−2, and can maintain stable at 10C with an ultrahigh specific capacity of 110 mAh/g. Furthermore, it can also be coupled with a LiNi0.5Co0.2Mn0.3O2 (NCM523) and a high surface load of LiFePO4 (LFP) cathode (11.5 mg cm−2). This research might open a window for the understanding of the Li deposition behavior and pave the way to develop other alkali-metal-ion batteries.

Three-Dimensional Vanadium and Nitrogen Dual-Doped Ti3C2 Film with Ultra-High Specific Capacitance and High Volumetric Energy Density for Zinc-Ion Hybrid Capacitors.

Zinc-ion hybrid capacitors (ZICs) can achieve high energy and power density, ultralong cycle life, and a wide operating voltage window, and they are widely used in wearable devices, portable electronics devices, and other energy storage fields. The design of advanced ZICs with high specific capacity and energy density remains a challenge. In this work, a novel kind of V, N dual-doped Ti3C2 film with a three-dimensional (3D) porous structure (3D V-, N-Ti3C2) based on Zn-ion pre-intercalation can be fabricated via a simple synthetic process. The stable 3D structure and heteroatom doping provide abundant ion transport channels and numerous surface active sites. The prepared 3D V-, N-Ti3C2 film can deliver unexpectedly high specific capacitance of 855 F g-1 (309 mAh g-1) and demonstrates 95.26% capacitance retention after 5000 charge/discharge cycles. In addition, the energy storage mechanism of 3D V-, N-Ti3C2 electrodes is the chemical adsorption of H+/Zn2+, which is confirmed by ex situ XRD and ex situ XPS. ZIC full cells with a competitive energy density (103 Wh kg-1) consist of a 3D V-, N-Ti3C2 cathode and a zinc foil anode. The impressive results provide a feasible strategy for developing high-performance MXene-based energy storage devices in various energy-related fields.

All-functionalized-graphene ribbon films for flexible asymmetric supercapacitors with ultrahigh energy and power densities

Asymmetric (hybrid) supercapacitors (ASCs) based on different positive and negative pseudocapacitance materials can deliver more energy density than electric double layer capacitors (EDLCs). Yet, few pseudocapacitive materials can provide high energy and power density, simultaneously, due to their poor conductivity and unfavorable reaction kinetics under fast charge/discharge rates. Here, we graft sulphur- and oxygen- functionalized into interconnected graphene ribbons to improve the accessibility of ion and enhance redox-active sites. The prepared sulphur- and oxygen- functionalized interconnected graphene ribbon (S-IGR and O-IGR) films as positive electrode and negative electrode, respectively, for high energy density flexible ASCs. Benefiting from the more “active sites” for the graphene ribbons, the S-IGR and O-IGR films connect more sulphur and oxygen groups. As a result, the S-IGR and O-IGR films exhibit ultra-high specific capacitance of 1660 F g−1 (1.66 F cm−2) and 428 F g−1 (0.43 F cm−2), respectively. More importantly, the assembled O-IGR//S-IGR ASCs based on aqueous and gel electrolytes exhibit ultra-high energy densities of 106.6 Wh kg−1 and 35.6 Wh kg−1, respectively. With the ultrafast charging and discharging capability, the ASCs based on aqueous electrolytes can be charge/discharged within 0.53 s to deliver high energy density of 15.0 Wh kg−1 and ultrahigh-power density of 101.4 kW kg−1. Thus, this strategy could possibly be used as designing and fabricating new generation of all grphene-based ASCs with high energy and power densities.

High density Ti3C2TX-graphene quantum dot-Ru monolithic film electrode with rich anisotropic microstructures for high-performance supercapacitor and piezoresistive pressure sensor

Ti3C2TX become a promising electrode and pressure sensing material because of high conductivity. However, poor anisotropy limit its practical applications in high-performance pressure sensor. This study reports one solution for protonated arginine and serine-functionalized graphene quantum dot (RS-GQD+)-regulated synthesis of Ti3C2TX-Ru monolithic film. Dropped RS-GQD + aqueous solution to Ti3C2TX aqueous solution to initiate the self-assembly of Ti3C2TX sheets. Followed by reaction with RuCl3 to produce Ru nanocrystals and subsequent vacuum filtration. Adjusting amounts of RS-GQD + results in formation of monolithic Ti3C2TX-Ru film with ultrahigh density of 3.52 g cm−3 and rich anisotropic microstructures. The structure achieves to excellent supercapacitor and pressure sensing behavior. The soft symmetrical supercapacitor with Ti3C2TX-Ru film electrodes without current collector, conductive agent and binder exhibits ultrahigh specific capacitance of 779.3 F g−1 at 1 A g−1 (1828.7 F cm−3) and energy density of 43.8 W h kg−1 at 225 W kg−1. The Ti3C2TX-Ru film pressure sensor offers high-resolution distinguish subtle and complex pressure changes with superhigh sensitivity and precision. Its piezoresistive current linearly increases with increasing pressure between 0.02 and 30 kPa with detection limit of 0.0067 kPa. The self-powered pressure sensor shows broad application prospect in monitoring human movement, writing and facial expression.

Structural Design of 3D Current Collectors for Lithium Metal Anodes: A Review.

Due to the ultrahigh theoretical specific capacity (3860 mAh g-1) and low redox potential (-3.04 V vs. standard hydrogen electrode), Lithium (Li) metal anode (LMA) received increasing attentions. However, notorious dendrite and volume expansion during the cycling process seriously hinder the development of high energy density Li metal batteries. Constructing three-dimensional (3D) current collectors for Li can fundamentally solve the intrinsic drawback of hostless for Li. Therefore, this review systematically introduces the design and synthesis engineering and the current development status of different 3D collectors in recent years (the current collectors are divided into two major parts: metal-based current collectors and carbon-based current collectors). In the end, some perspectives of the future promotion for LMA application are also presented.

Oxygen-enriched vacancies Co3O4/NiCo2O4 heterojunction hollow nanocages with enhanced electrochemical properties for supercapacitors

Research into environmentally friendly energy storage devices is a vital strategy to address the energy crisis and environmental pollution challenges. In this paper, oxygen-rich vacancy Co3O4/NiCo2O4 heterojunction hollow nanocage electrodes were synthesized by a two-step hydrothermal and calcination method. Taking advantage of its unique structure, oxygen vacancies, and the synergistic effect of multi-element transition metal oxides, the electrode has good conductivity, high specific surface area, and abundant active sites. As a result, the Co3O4/NiCo2O4 HHNCs electrode exhibits an ultra-high specific capacitance of 1788F g−1 at 1Ag-1, and the assembled hybrid supercapacitor has an energy density of up to 43.9 Wh kg−1, which is promising for applications in energy storage materials.

Two-step pyrolysis of mango branch for the preparation of B/N/O co-doped porous carbon materials

Porous carbon prepared by conventional pyrolysis of forestry waste usually possesses poor specific capacitance as supercapacitor electrodes, which mainly attributes to the shortcomings of its poor microstructure and few chemical functional groups on the surface. It is suggested that the introduction of active groups can enhance the wettability and induce redox reactions, thereby increasing the specific capacitance. In this paper, novel functional carbon materials with high electrochemical activity were effectively prepared from forestry waste by a green and economical B/N/O co-doping synthesis strategy using NH4B5O8 as bi-functional additive. The doped content of heteroatoms, specific surface area, and pore features were controlled by adjusting the NH4B5O8 mixing ratio and pyrolysis temperature. MA3-T700 showcases a specific surface area of 1621 m2/g, preferable B/N/O atoms doped content (0.62%, 1.98%, and 13.82%, respectively), and interconnected micropores/mesopores structure. It exhibits an ultra-high specific capacitance of 322 F/g at 1 A/g and an exceptional rate performance of 77.02% even at 20 A/g. Furthermore, MA3-T700 symmetric supercapacitor was assembled, exhibiting an impressive capacitance retention of 96.11% after 10,000 cycles and achieving an energy density of 8.4 Wh/kg. This work provides technical and theoretical support for the utilization of high-value resources from forestry waste.

Overall collaborative contribution of electrodeposited NiFe2O4@Ni0.75Fe0.25S2 composites for high performance supercapacitors

In this work, a three-dimensional layered NiFe2O4@Ni0.75Fe0.25S2 composite has been synthesised by a two-step electrodeposition process. In the 3 M KOH aqueous solution system, the NiFe2O4@Ni0.75Fe0.25S2 composite exhibits good electrochemical properties due to the overall synergistic effect of the two components. The layered nanostructures provide a high surface area, which increases the specific capacity of NiFe2O4@Ni0.75Fe0.25S2@NF. The current density is 1 A g−1 and the maximum specific electrostatic capacity is 734 C g−1. The construction of an asymmetric supercapacitor (ASC) involves the assembly of NiFe2O4@Ni0.75Fe0.25S2@NF//AC@NF. Operating at a current density of 1 A g−1, this ASC achieves an impressive maximum specific electrostatic capacity of 734 C g−1. In particular, the assembled NiFe2O4@Ni0.75Fe0.25S2 @NF//AC@NF ASC exhibits exceptional electrochemical performance. In particular, it demonstrates an ultra-high specific capacitance of 463 C g−1 at a current density of 1 A g−1, coupled with excellent cycle stability. Even after 10,000 charge-discharge cycles at a current density of 10 A g−1, only 3.6 % of the initial specific capacitance is lost. These impressive results show that NiFe2O4@Ni0.75Fe0.25S2@NF electrodes offer a new solution for the design of high performance aqueous supercapacitors.

Functionalizing the surface of polyetherimide (PEI)-based cross-linked separator by introducing the polyamide layer through interfacial polymerization and adding boric acid as electrolyte additive for boosted performance in lithium‑oxygen battery

Lithium‑oxygen battery is a very promising energy storage device for its ultrahigh specific capacity. However, due to the undecomposable insulating oxidation species accumulated on the cathode and the safety issues caused by dendrite penetration, the cycling performance of lithium‑oxygen battery is seriously restricted. Herein, through interfacial polymerization (IP) method, a polyetherimide (PEI)-based separator with dense polyamide thin layer was prepared. And the PEI-based separator is cross-linked with Polyethylene polyamines (PEPA) and undergoes 1,3,5-benzenetricarbonyl chloride (TMC) amidation. According to the SEM result, the obtained polyamide layer is well cross-linked with the PEI-based separator and at the same time it owns a dense micro-pore structure, which ensures a battery structure stability and a good electrochemical performance of the separator. Moreover, the increased IP layer amidated by TMC can not only greatly increase the ionic conductivity of the polyamide/polyetherimide (P/PEI) cross-linked separator to 1.0 mS cm−1, but also significantly decrease the interfacial impedance between the PEI and the electrode. With all these merits, the battery assembled with the representative P/PEI2 separator shows boosted cycling performance of over 90 cycles at a capacity of 1000 mAhg−1. Besides, the electrophilic boric acid was introduced to reduce the interaction between anions and cations, resulting in effectively promoted transport efficiency of lithium ions and the cycling life of the battery can be even prolonged to 108 cycles at a capacity of 1000 mAhg−1.

3D nanocubes NiCo-PBA sulfide for high-performance supercapacitors

In this work, 3D nanocubes NiCo-PBA sulfide (NiCoS-PBA) has been prepared by ammonia solution etching and vulcanizing for NiCo-Prussian blue analogue (NiCo-PBA) homemade. The SEM and TEM show that the obtained NiCoS-PBA has the 3D nanocubes structure with rough surface and inward depressions. Electrochemical analysis indicates that an ultrahigh specific capacitance of NiCoS-PBA is 965 C g−1 at 1 A g−1, which is better than that of NiCo-PBA# (256 C g−1), only sulfurized NiCoS-PBA# (369 C g−1) and only etched NiCo-PBA (281 C g−1) at the same condition. This is thanks to the 3D nanocubes structure, which has large accessible areas and rich active sites for redox reactions to enhance the electrochemical performance of supercapacitors. Meanwhile, this also illustrates that the etching and vulcanizing treatments can significantly boost the specific capacitance of NiCoS-PBA. Additionally, the NiCoS-PBA-based asymmetric supercapacitor (ACS) device offers an energy density of 61.7 Wh kg−1 at a power density of 800.1 W kg−1. It is believed that NiCoS-PBA will be a strong contender as an electrode material in supercapacitors.

In Situ Phase Transformation to form MoO3−MoS2 Heterostructure with Enhanced Printable Sodium Ion Storage

AbstractMolybdenum trioxide (MoO3) possesses high energy density but often suffers from poor electrical conductivity and limited cycling stability when used as a sodium‐ion battery (SIB) anode. To address these issues, the construction of （Molybdenum trioxide‐Molybdenum disulfide）MoO3‐MoS2 heterostructures has proven effective in enhancing electronic conductivity, ion diffusion properties, and structural stability. Guided by the density functional theory (DFT) calculations, which predict favorable Na+ diffusion and adsorption properties, nanorod‐like MoO3‐MoS2 heterostructures are synthesized using a two‐step method. Benefiting from the synergistic effects of the heterostructure and nanosized morphology, the resulting MoO3‐MoS2 electrode exhibits outstanding rate performance (316 mA h g−1 at 10 A g−1) and long‐lasting cycling stability (286 mA h g−1 after 2300 cycles at 5 A g−1) as an SIB anode. In situ XRD measurements reveal that the ultrahigh specific capacity of MoO3‐MoS2 is attributed to the synergistic intercalation‐conversion storage of MoO3 and MoS2. In the pursuit of meeting commercialization requirements, electrodes with adjustable mass loading are also prepared using 3D printing, showcasing the high areal capacity characteristics of the SIBs. This study not only provides theoretical insights into expanding the use of heterojunction materials as SIB anodes but also demonstrates the significant potential for creating high‐energy‐density and cost‐effective SIBs.

Hierarchical three-dimensional nanoflower-like CuCo2O4@CuCo2S4@Co(OH)2 core-shell composites as supercapacitor electrode materials with ultrahigh specific capacitances

Here, we prepare three-dimensional nanoflower-shaped CuCo2O4@CuCo2S4@Co(OH)2 core–shell materials on nickel foam (NF). CuCo2O4 (CuC) nanowire arrays and CuCo2S4 (CuS) nanosheets are grown directly on NF as the core through routine hydrothermal and high-temperature calcination methods and Co(OH)2 (CH) small nanosheets deposited on CuC@CuS nanoflowers via the potentiostatic deposition for 15 mins. Due to its distinctive structure and the synergistic effect between multiple components of CuCo2O4@CuCo2S4@Co(OH)2, the electrode has a fantastic specific capacitance (Cs, 4075F/g) under the current density of 1 A/g and satisfying cyclic stability (88.4 % capacitance retention and 84.6 % coulomb efficiency after 10,000 cycles). Additionally, an asymmetric supercapacitor (ASC) device equipped with CuC@CuS@CH-15/NF as a positive and active carbon (AC) electrode as a negative electrode can work steadily at 0–1.6 V. The ASC device can offer an excellent energy density (E, Wh kg−1) of 232.02 Wh kg−1 at a high-power density of 2879.8 W kg−1 (P, W kg−1) and an unexpected cycle stability (84.2 % of the original Cs and 81.7 % of coulombic efficiency after 10,000 repeated GCD tests), which far surpasses other ASCs of the same type. These results guide to enhancement of the electrochemical properties of cobalt-based oxides/sulfides@Co(OH)2 as the positive electrode for supercapacitors.

Carbon-coated Ni2P nanoparticles coated on CNTs synthesized by an in-situ solid-state method for high-performance hybrid supercapacitors and lithium-ion batteries

The pursuit of electrode materials with excellent performance in both supercapacitors and lithium-ion batteries holds the potential to streamline the construction of hybrid electrochemical energy storage systems and contribute to cost reduction. In this paper, we introduce a novel nanocomposite—carbon-coated Ni2P nanoparticles coated on CNTs (CNTs@(Ni2P@C))—via an in-situ one-step solid-state method. This design not only prevents the aggregation of Ni2P nanoparticles with a size of 5–8 nm but also mitigates its volume change during charging and discharging cycles. Simultaneously, it establishes a rapid electron transfer pathway between CNTs and Ni2P nanoparticles, enhancing the electron transport kinetics within the synthesized nanocomposite. The synthesized CNTs@(Ni2P@C) nanocomposite exhibits high performance in both SCs and LIBs. An ultra-high specific capacity of 378.5 mAh g−1 (2725.2 F g−1) at 1 A g−1 and a good rate capacity (189.3 mAh g−1 at 20 A g−1) are achieved when used in supercapacitors. The hybrid supercapacitor device assembled using the synthesized nanocomposite exhibits a high specific capacity of 84.3 mAh g−1 at 1 A g−1 and excellent capacity retention of 92 % after 10,000 cycles. A high energy density of 67.47 Wh kg−1 can be delivered at a power density of 0.84 kW kg−1. When used in LIBs, the synthesized nanocomposite exhibits a reliable reversible specific capacity of 329 mAh g−1 at 0.1 A g−1 after 100 cycles and a high capacity retention of 90 % after 5000 cycles at 2.0 A g−1. The proposed in-situ solid-state method and the synthesized CNTs@(Ni2P@C) nanocomposite will strongly promote the development of difunctional electrode materials for supercapacitors and lithium-ion batteries.

Integrated anode with 3D electron/ion conductive network for stable lithium metal batteries

Lithium metal anode has attracted increasing attention due to its ultra-high theoretical specific capacity and low redox potential. However, the severe interface problems caused by the parasitic reactions at the anode/separator interface greatly hinder its applications. Herein we design a 3D lithium−boron (LiB) fiber integrated lithium anode with polypropylene separator through the interfacial adhesive strategy with poly(vinylidene fluoride-co-hexafluoropropylene)-based polymer electrolyte. The 3D Li/LiB anode after chemical etching can increase the exchange current density to 36.8 mA cm−2, which is about 14 times the value of the pristine anode with 2.6 mA cm−2. Meanwhile, the poly(vinylidene fluoride-co-hexafluoropropylene)-based polymer electrolyte ensures high ionic conductivity and interfacial stability. Thus, the integrated anode with 3D electron/ion conductive network can guide Li deposition away from the unsafe anode/separator interface, and directly suppress the growth of lithium dendrites. As a result, the integrated anode with LiNi0.83Mn0.06Co0.11O2 cathode exhibits an excellent discharge capacity of 168.3 mAh g −1 at a high current density of 5 C. Besides, the rigid LiB skeleton coupling with flexible PVDF-HFP-based polymer electrolyte can effectively prevent the pulverization of lithium anode during long-term cycling, showing superior cycling stability of 1000 cycles at 1 C with a capacity retention of 76 %. This work provides a promising integrated anode for stable lithium metal batteries without lithium dendrite growth.

Effective assembling of nickel oxide-reduced graphene oxide heterostructures for ultrahigh capacity supercapattery

Developing new materials to facilitate sustainable and renewable energy storage is the most sought research frontier of the current era. In this regard, supercapacitors have drawn huge research attention in developing efficient electroactive materials. Herein, a nickel oxide/reduced graphene oxide (NiO-rGO) composite has been synthesized using the facile precipitation-aging-calcination and ultrasonication technique for energy storage applications. Due to the composite's enhanced surface area and the synergistic effect of redox-active NiO and highly conductive rGO, the resulting heterostructure exhibits excellent performance as a supercapattery. The electrochemical investigations show that the designed NiO-rGO heterostructure exhibits battery-type electrode features with an ultrahigh specific capacity of 850 Cg-1 at 1 Ag-1 current density with 91 % capacity retention even after 5000 charge-discharge cycles. The efficacy of this composite has also been tested in a symmetrical device assembly (NiO-rGO//NiO-rGO), which shows a very high maximum energy density (56.6 Wh.kg−1) and power density (9.65 kW kg−1) with excellent performance retention for 10000 charge/discharge cycles. Further, the experimental charge storage outcomes of the materials have also been supported by calculating the energetics of OH* adsorption using DFT. This work provides a facile approach to maximize the synergistic interactions within metal oxides-rGO-based 3D/2D heterostructures to derive improved electrochemical features. Moreover, it also offers experimental and theoretical insights into designing efficient and cost-effective materials for energy storage.

Boosting supercapacitor performance with a cobalt hydroxide in-situ preparation orange peel biochar flower-like composite

In this study, we present a novel composite material known as Cobalt oxide/orange peel-derived biochar (CoNF@OBC), which exhibits a distinctive flower-like structure and showcases exceptional potential for high-performance supercapacitors. The CoNF@OBC composite is created by employing Co(OH)2 as a supporting material. The inherent hierarchical and porous structure of CoNF@OBC facilitates efficient flow and dispersion of ions and electrons within the electrolyte. This structural advantage results in shorter diffusion pathways and enhanced conductivity, rendering CoNF@OBC highly suitable for energy storage applications. Remarkably, CoNF@OBC demonstrates an ultra-high specific capacitance of 563 F g−1 at a current density of 1 A g−1, with an outstanding capacitance retention of 96 % even after undergoing 10,000 charge-discharge cycles. When integrated into a device, CoNF@OBC yields a specific capacitance of 124 F g−1. Furthermore, the Ragone plot for the symmetric device reveals an energy density ranging from 10 to 41 Wh kg−1, accompanied by power densities spanning from 811 to 5143 W kg−1. This remarkable performance highlights the extensive potential of CoNF@OBC in practical applications, supported by its long-term cyclic stability of 92 % after 10,000 charge-discharge cycles. This study underscores the sustainability aspect of utilizing agricultural waste, such as orange peels, as eco-friendly carbon sources. By combining these waste materials with various metal hydroxides for eco-friendly supercapacitor electrodes, promoting sustainable energy storage solutions.

Porous Magnesium Hydride Nanoparticles Uniformly Coated by Mg‐Based Composites toward Advanced Lithium Storage Performance

Magnesium hydride (MgH2) has been recognized as a promising anode material of lithium‐ion batteries (LIBs) owing to its ultrahigh specific capacity. The low conductivity and the structural pulverization induced by large volume expansion, however, has long limited its practical lithium storage performance. Herein, a series of yolk‐shell‐like structures, composed of porous MgH2 nanoparticles (NPs) decorated with Mg‐based composites through in‐situ solid‐gas reaction using MgH2 as both the reactant and the structural template, have been fabricated and uniformly dispersed on electronically conductive graphene. It could not only physically accommodate the volume change of MgH2 owing to the physical protection of Mg‐based composites and the formation of void space inside MgH2 NPs, but also effectively facilitate the transportation of electrons throughout the whole electrode. Particularly, the uniform decoration of ultrathin Mg(BH4)2 as the shell with thermodynamically favorable intercalation of lithium ions and low kinetic barrier for the lithium‐ion diffusion promotes facile transportation of lithium ions into active MgH2, which, coupled with the porous structure constructed by flexible graphene, effectively improves the ion conductivity of the electrode. The synergistic improvement in electronic and ionic conductivity leads to a high reversible capacity of 1651 mAh g−1 at 200 mA g−1 after 380 cycles.