Desirable Energy Density Research Articles

Cauliflower-like Ni/NiCoP@Boron-doped diamond composite electrodes for high-performance symmetric supercapacitors

Due to the lack of electrocatalytic active sites, the supercapacitors (SCs) even based on the most stable sp3 carbon material (Boron-doped diamond) suffer from poor capacitance and low energy density. Herein, a cauliflower-like biphasic Ni/NiCoP layer has been successfully deposited on the BDD film and further applied as binder-/current collector-free SC electrodes. In a redox-active aqueous electrolyte (0.05 M Fe(CN)63−/4− + 1.0 M KOH), the Ni/NiCoP@BDD electrode with exceptional cyclic stability (∼89.0 % after 10,000 cycles) delivers a specific capacitance of 256.1 mF cm−2 at a current density of 30 mA cm−2, about 2 times higher than that in inert electrolyte. Furthermore, such a symmetric PC device provides a desired energy density of 70.0 Wh kg−1 at a high power density of 3601 W kg−1.

Weak nonlinearity engineering induced excellent low-field energy storage performance in BNTST-based lead-free relaxors

With continuously developing of electronic power systems, ceramic dielectrics with superior energy-storage performance have received widespread attention. Relaxor ferroelectric ceramics have become a research hotspot due to the small hysteresis, while how to modify the strong nonlinear and limited polarization difference is still a huge challenge for achieving a desirable discharge energy density (Wdis). In this work, a linear-like relaxors system with high polarization is constructed by introducing antiferroelectric phase (NaNbO3, NN) into relaxor ferroelectric phase (0.6Bi0.5Na0.5TiO3-0.4SrTiO3, BNTST). Benefitting from the improvement on DC-bias stability and the high zero-field dielectric constant, the 0.90BNTST-0.10NN ceramic successfully keeps a high effective dielectric constant even at high electric fields (εr@120kV/cm=1670), which ensures the high polarization and optimized linearity of P-E loops. As a result, 0.90BNTST-0.10NN ceramics achieve superior energy storage performance with a high Wdis (5.79 J/cm3) and high efficiency (91.5 %). These findings provide an effective nonlinearity-weakening approach to explore promising candidate in practical energy-storage applications.

Dendrite-free zinc metal anode for long-life zinc-ion batteries enabled by an artificial hydrophobic-zincophilic coating

Considering the desired energy density, safety and cost-effectiveness, rechargeable zinc-ion batteries (ZIBs) are regarded as one of the most promising energy storage units in next-generation energy systems. Nonetheless, the service life of the current ZIBs is significantly limited by rampant dendrite growth and severe parasitic reactions occurring on the anode side. To overcome these issues caused by poor interfacial ionic conduction and water erosion, we have developed a facile strategy to fabricate a uniform zinc borate layer at the zinc anode/electrolyte interface (ZnBO). Such protective layer integrates superhydrophobic-zincopholic properties, which can effectively eliminate the direct contact of water molecules on the anode, and homogenize the interfacial ionic transfer, thereby enhancing the cyclic stability of the zinc plating/stripping. As a result, the as-prepared ZnBO-coated anode exhibits extended lifespan of 1200 h at 1 mA cm−2 and demonstrates remarkable durability of 570 h at 20 mA cm−2 in Zn||Zn symmetric cells. Additionally, when coupled to an NH4V4O10 (NVO) cathode, it also delivers a superior cyclability (203.5 mAh/g after 2000 cycles at 5 A/g, 89.3 % capacity retention) in coin full cells and a feasible capacity of 2.5 mAh at 1 A/g after 200 cycles in pouch full cells. This work offers a unique perspective on integrating hydrophobicity and zincophilicity at the anode/electrolyte interface through an artificial layer, thereby enhancing the cycle lifespan of ZIBs.

Light-weight flexible symmetric supercapacitors based on magnesium-zinc codoped MnO2 nanostructures on carbon cloth as enhanced-performance binder-free electrodes

Developing advanced flexible supercapacitors with high energy and power density is a critical research goal. One promising approach involves combining manganese dioxide (MnO2) with a three-dimensional carbon substrate. This strategy leads to the creation of supercapacitor electrode materials that exhibit high specific capacitance, stability, and environmental friendliness. However, the challenge lies in addressing the low electrical conductivity of MnO2, which limits the rate of electron transfer. The incorporation of metal ions enhances the conductivity of manganese oxide, resulting in a significant increase in lattice defects. These defects create abundant active sites for energy storage. In this study, we developed flexible electrodes based on magnesium-doped MnO2, zinc-doped MnO2, and magnesium-zinc codoped MnO2 nanostructures deposited on carbon cloth (CC) via a one-step hydrothermal method. The supercapacitive behavior of these electrodes was investigated using CV and GCD measurements. The as-prepared electrodes exhibit good electrical conductivity, and their interconnected network structure, composed of sponge-shaped nanostructure layers, results in a large specific surface area. This network also facilitates efficient pathways for effective electron transport. The optimized Mg-Zn codoped MnO2@CC sample exhibits a high capacitance of 79.9 mF/cm² at 0.7 mA/cm² and good rate performance, reaching around 46.59 mF/cm² up to 1.5 mA/cm² in the three-electrode system. Notably, the areal capacitance values calculated from the CV curves for all Mg-Zn codoped MnO2@CC electrodes surpass those of Mg-doped MnO2@CC and Zn-doped MnO2@CC. A flexible symmetric supercapacitor assembled using the best Mg-Zn codoped MnO2@CC as both positive and negative electrodes and PVA-Na2SO4 gel electrolyte delivers a desirable energy density of 0.196 mWh/cm2 at 2.38 mW/cm2. Furthermore, this fabricated supercapacitor demonstrates a broad voltage window of 2.25 V and remarkable cycling stability, retaining 83 % of its initial performance after 4000 charge-discharge cycles.

High-energy fiber-shaped calcium-ion batteries enable integrated wearable electronics for human body monitoring

Electronic textiles hold the merits of high conformability with the human body and natural surrounding, possessing large market demand and wide application foreground in smart wearable and portable devices. However, their further application is largely hindered by the shortage of flexible and stable power sources with multifunctional designability. Herein, a free-standing ZnHCF@CF electrode (ZnHCF grown on carbon nanotube fiber) with good mechanical deformability and high electrochemical performance for aqueous fiber-shaped calcium ion battery (FCIB) is reported. Benefiting from the unique Ca2+/H+ co-insertion mechanism, the ZnHCF@CF cathode can exhibit great ion storage capability within a broadened voltage window. By pairing with a polyaniline (PANI)@CF anode, a ZnHCF@CF//PANI@CF FCIB is successfully fabricated, which exhibits a desirable volumetric energy density of 43.2 mWh cm−3 and maintains superior electrochemical properties under different deformations. Moreover, the high-energy FCIB can be harmoniously integrated with a fiber-shaped strain sensor (FSS) to achieve real-time physiological monitoring on knees during long-running, exhibiting great promise for the practical application of electronic textiles.

Ultrahigh efficiency and energy density in tri-layered ferroelectric polymer composites utilizing ultralow loading of micro-sized plates

Ferroelectric-based composites have demonstrated tremendous potential in electrostatic capacitor owing to their exceptional dielectric characteristics. However, it is extremely challenging to attain desirable energy density (Ue) and above 95% efficiency (η) under low electric fields in the ferroelectric polymer-based composites because of the dominating electrical conduction loss. Herein, ferroelectric polymer composites consisting of SrTiO3@SiO2 plates/(PVDF-co-HFP) as the inner layer and polycarbonate (PC) as the outer polymer layers are elaborately proposed. The vital role of the multiple interlaminar interfaces (electrode/dielectric interface and interlayer interface) on the reduction of conduction loss and improvement of corresponding energy storage properties of the ferroelectric polymer is verified by experimental and theoretical simulations. The resulting composite with an ultralow loading of SrTiO3@SiO2 plates (0.5 vol%) displays a record high capacitive performance (∼8.73 J/cm3) at above 95% η under the low electric field of 280 MV/m1, indicating an enormous ∼118% increment of the maximal Ue over the commercial bench-mark biaxially oriented polypropylene (∼4 J/cm3) and far outperforming those of the polymer-based dielectrics reported to date. Along with fast discharge time (9 ns), this contribution presents a versatile and competitive technology for fabricating composites with exceptional energy storage capabilities operating under low electric fields.

Introduction of bimetallic oxide-modified carbon nanotubes for boosting the energy storage performance of NiCo-LDH based in-plane micro-supercapacitors on paper

In-plane micro-supercapacitors (IMSCs) have greater promise for use in flexible wearable electronics than traditional stacked configurations due to their ease of integration and conformability. Nickel-cobalt layered double hydroxide (NiCo-LDH) has garnered significant interest as a stellar material for supercapacitors because of its affordable price, regular morphology, and high theoretical capacity. Unfortunately, the intrinsic poor conductivity of LDH materials prevents supercapacitors from achieving long-term stable cycling and the desired energy density. This research successfully applies the self-templated approach to prepare carbon nanotubes (CNTs) with heterogeneous architectures and numerous phase interfaces, thereby mitigating this disadvantage. Carbon nanosheets adorned with WO2 and MoO2 nanoparticles assemble the CNT with a typical three-dimensional structure. When combined with LDH in a suitable ratio, the composite electrode’s conductivity significantly improves, providing increased capacity and cycling stability. Compared to commercial CNTs, the larger size of the prepared WO2/MoO2@P, N-CNTs serves a superior supporting and connecting role, thereby preventing the NiCo-LDH from aggregating. Under the best conditions, the composite electrode demonstrates a capacity of 1237 C/g at 1 A g−1 and an optimal capacity retention of more than 92%. For the IMSC devices, the composite materials as the positive electrode achieve an energy density of 0.0590 mWh cm−2, and no capacity degradation is observed after 10,000 cycles. In addition, bending tests have demonstrated the mechanical stability of the IMSCs. Therefore, this strategy of mixing highly conductive WO2/MoO2@P, N-CNTs can effectively improve the conductivity of the composite material and the mechanical properties of the overall device. Furthermore, this concept can be further extended to the preparation and application of other wearable devices.

Strain-driven high energy storage in BaTiO3-based lead-free epitaxial thin films

In this work, the epitaxial 0.85BaTiO3-0.15Bi(Mg1/2Ti1/2)O3 (BT-BMT) films with large compressive strain were fabricated on SrTiO3 (001). The expansion of the unit cell volume and out-of-plane lattice parameter and the large built-in electric field (Ebi) in BT-BMT films indicate the existence of defect dipoles. It was found that the polarization and the breakdown strength can be optimized by the strain and the defects, respectively. Ultimately, a desirable energy density of 90.3 J/cm3 with efficiency of 62.3% was achieved. It suggests that strain can serve as a practical means to modulate the energy storage performance of ferroelectric epitaxial film capacitors.

High-Energy Symmetric Li-Ion Battery Enabled by Binder-Free FeOF-MXene Heterostructure with Doubly Matched Capacity and Kinetics.

Fluorides are viewed as promising conversion-type Li-ion battery cathodes to meet the desired high energy density. FeOF is a typical member of conversion-type fluorides, but its major drawback is sluggish kinetics upon deep discharge. Herein, a heterostructured FeOF-MXene composite (FeOF-MX) is demonstrated to overcome this limitation. The rationally designed FeOF-MX electrode features a microsphere morphology consisting of closely packed FeOF nanoparticles, providing fast transport pathways for lithium ions while a continuous wrapping network of MXene nanosheets ensures unobstructed electron transport, thus enabling high-rate lithium storage with enhanced pseudocapacitive contribution. In/ex situ characterization techniques and theoretical calculations, both reveal that the lithium storage mechanism in FeOF arises from a hybrid intercalation-conversion process, and strong interfacial interactions between FeOF and MXene promote Li-ion adsorption and migration. Remarkably, through demarcating the conversion-type reaction with a controlled potential window, a symmetric full battery with prelithiated FeOF-MX as both cathode and anode is fabricated, achieving a high energy density of 185.5Whkg-1 and impressive capacity retention of 88.9% after 3000 cycles at 1Ag-1. This work showcases an effective route toward high-performance MXene engineered fluoride-based electrodes and provides new insights into constructing symmetric batteries yet with high-energy/power densities.

High performance Al anode for Al-air battery enabled by coordinating In and Sb additions with discharge parameters

High performance of Al anode for Al-air battery was achieved via coordinating minor In and Sb additions with discharge parameters. The electrochemical behaviors, discharge performance and surface structures of aluminum electrodes are systematically investigated to understand the alloying chemistry coordination of indium and antimony. The results show that coordinating indium and antimony can significantly activate the Al electrode without aggravating the hydrogen evolution. The assembled Al-air cell with Al-0.05In-0.05Sb electrode exhibits a desirable specific capacity and energy density of 2638 Ah·kg−1 and 3166 Wh·kg−1, respectively. Furthermore, antimony has better activating effect than indium, especially at discharge current density over 40 mA·cm−2. The activating mechanisms are discussed in detail.

Interfacial regulation of biomass-derived carbon towards high-performance supercapacitor

Interfacial regulation for carbon-based materials plays critical role for supercapacitive performance improvement and the strategies about introducing heteroatomic groups and tuning specific surface area can be proposed to effectively address the low specific capacitance issues. Thus, the approaches about activation treatment with nitric acid (APC-H800) and copper chloride (APC-C800) for biomass-derived carbon materials have been raised and systematically investigated. Consequently, though the above chemical activation treatment, the oxygen and nitrogen functional groups can be introduced for APC-H800. Meanwhile, the specific surface area of APC-C800 has been significantly increased. Significantly, the upper specific capacitance of 384 F g−1 and 423 F g−1 for APC-H800 and APC-C800 electrodes can be achieved at a current density of 1.0 A g−1, what matters more is that two symmetric devices offer superior energy density and desirable cycling stability (no decrease that occurs after 10,000 cycles) are successfully assembled by employing APC-H800 and APC-C800 electrodes, respectively. More significantly, desirable energy density about 11.18 Wh kg−1 and 12.5 Wh kg−1 at 249.98 W kg−1 and 250 W kg−1 have been achieved for the symmetric supercapacitor devices of APC-H800//APC-H800 and APC-C800//APC-C800. These modification strategies shed insight into the sensible design of a further stage of advanced art carbon electrodes for powerful performance supercapacitors.

A New Design Strategy Enables High Mn‐Utilization Rate in Aqueous Zinc–Manganese Batteries: Constructing Cathodic Local Mn‐Rich Region

AbstractThe deposition–dissolution mechanism with a two‐electron transfer reaction endows aqueous Zn–Mn batteries with a desirable theoretical energy density. However, due to the limited solubility of traditional manganese‐based materials and the competitive Mn shuttle behavior, the practical performance is unsatisfactory. Herein, by synergistically incorporating a novel Mn‐rich Mn4N cathode with a plasma functionalized carbon nanotubes film (PCNT) interlayer, an aqueous Zn–Mn battery with a high Mn‐utilization rate and high energy/power density is successfully developed. Specifically, the Mn4N cathode boasts high manganese content and dissolution activity, thereby offering a copious supply of Mn2+ ions for the battery system. The PCNT interlayer, with abundant micropore structures and functional groups, not only restrains the Mn2+ shuttle by entrapping the dissolved Mn2+ but also offers copious reaction sites, ensuring concentrating Mn2+ on the cathodic side and maximizing their contribution to the electrochemical reaction. Consequently, Mn4N‐PCNT exhibits a low polarization voltage and superior Mn‐utilization rate (64.8%). Without the MnSO4 additive, Mn4N‐PCNT achieves an ultra‐high energy density of 821.9 W h kg−1 and remarkable long‐term cycling stability (90% capacity retention over 9000 cycles). The delightful results demonstrate the practical application potential of Mn4N‐PCNT and open up new avenues for the rational design of advanced Zn–Mn batteries.

Eggshell as a biotemplate for the synthesis of layered porous carbon by co-pyrolysis with eucalyptus leaves

Based on its substantial specific surface area (SSA), quick ion transport path, and excellent pore structure, biomass carbon is a common ingredient in energy storage materials. In this study, hierarchical porous carbon was fabricated by the hard template method, using eucalyptus leaves (EL) as raw material, eggshells (ES) obtained from biomass waste act as a green biotemplating agent, and through co-pyrolysis technology to acquire high-value biomass carbon materials. A large SSA with a hierarchical porous structure displayed a honeycomb appearance obtained by adding eggshells in appropriate proportions. The ELES0.25 electrodes demonstrated a specific capacitance (Cs) of 310 F g−1 (0.5 A g−1) and 232 F g−1 (20 A g−1) in a three-electrode system, which displayed a capacitance retention of 74.8% with an outstanding electrochemical stability. The assembled ELES0.25//ELES0.25 symmetric supercapacitor displays a desirable energy density of 7.35 Wh kg−1 at a power density of 65 W kg−1 and preserves a capacitance retention of 97.38% after a charge/discharge cycle for 10,000 times. This research on ES acts as the biological template for assisted pyrolysis synthesis of porous carbon and proposes a novel approach for the clean and effective use of biomass waste.

Emerging application of 2D materials for dendrite-free metal batteries

Metal batteries using lithium, sodium, potassium, zinc, etc., as anodes have garnered tremendous attention in rechargeable batteries because of their highly desirable theoretical energy densities. However, large-scale application of these metal batteries is impeded by dendrite growth on the anode surface, which may penetrate the separator, leading to battery failure. Two dimensional (2D) materials featured by excellent mechanical strength and flexibility, tunable electronic properties and controllable assembly are promising materials for the construction of dendrite-free metal batteries. In this review, we summarize recent advancements of 2D materials for their potential use in critical components of dendrite-free batteries used as: (1) a host or artificial solid-electrolyte for metal anodes; (2) a solid electrolyte or modifier for electrolyte; and (3) an enhancement component for separators design. We conclude that 2D materials hold great promise for tackling the problems associated with dendrite formation by functioning as mechanical reinforcement and metal deposition regulators, along with improved safety, performance, and durability of batteries. Finally, this review discusses new perspectives and future directions in the field of 2D materials towards safe, high-energy metal batteries.

In Situ Construction of NiCoMn-LDH Derived from Zeolitic Imidazolate Framework on Eggshell-Like Carbon Skeleton for High-Performance Flexible Supercapacitors.

Active compounds based on LDH (ternary layered double hydroxide) are considered the perfect supercapacitor electrode materials on account of their superior electrochemical qualities and distinct structural characteristics, and flexible supercapacitors are an ideal option as an energy source for wearable electronics. However, the prevalent aggregation effect of LDH materials results in significantly compromised actual specific capacitance, which limits its broad practical applications. In this research, a 3D eggshell-like interconnected porous carbon (IPC) framework with confinement and isolation capability is designed and synthesized by using glucose as the carbon source to disperse the LDH active material and enhance the conductivity of the composite material. Second, by constructing NiCoMn-LDH nanocage structure based on ZIF-67 (zeolitic imidazolate framework-67) at the nanometer scale the obtained IPC/NiCoMn-LDH electrode material can expose more active sites, which allows to achieve excellent specific capacitance (2236 F g-1/ 310.6 mAh g-1 at 1 A g-1), good rate as well as the desired cycle stability (85.9% of the initial capacitance upon 5000 cycles test). The constructed IPC/NiCoMn-LDH//IPC ASC (asymmetric supercapacitor) exhibits superior capacitive property (135 F g-1/60.1 mAh g-1 at 0.5 A g-1) as well as desired energy density (40Wh kg-1 at 800W kg-1).

Oxygen-enriched pitch-derived hierarchically porous carbon toward boosted zinc-ion storage performance

The lack of cathode materials with satisfactory Zn2+ storage capability substantially hinders the realization of high-performance aqueous zinc-ion hybrid capacitors (ZHCs). Herein, we propose a facile KMnO4 template-assisted KOH activation strategy to prepare a novel oxygen-enriched hierarchically porous carbon (HPC-1-4). This strategy efficiently converts coal tar pitch (CTP) into a well-tuned carbon material with a large specific surface area of 3019 m2 g−1 and a high oxygen content of 9.20 at%, which is conducive to providing rich active sites, rapid charge transport, and appreciable pseudocapacitance for Zn-ion storage. Thus, the as-fabricated HPC-1-4-based aqueous ZHC exhibits prominent performance, including a high gravimetric capacity (206.7 mAh g−1 at 0.25 A g−1), a remarkable energy density (153.4 Wh kg−1 at 184.2 W kg−1), and an impressive power output (15240 W kg−1 at 63.5 Wh kg−1). In-depth ex-situ characterizations indicate that the excellent electrochemical properties of ZHCs are due to the synergistic effect of the Zn2+ adsorption mechanism and reversible chemisorption. In addition, the assembled quasi-solid-state device demonstrates excellent electrochemical stability of up to 100% capacity retention over 50000 cycles, accompanied with a desirable energy density of 115.6 Wh kg−1. The facile preparation method of converting CTP into carbonaceous functional materials has advanced the development of efficient and eco-friendly energy storage technologies.

Polyaniline spaced MoS2 nanosheets with increased interlayer distances for constructing high-rate dual-ion batteries

Dual-ion batteries (DIBs) have attracted great attention due to their affordable prices, environmental friendliness, and high operating voltage. However, the conventional graphite anode in DIBs has drawbacks such as unsatisfactory capacity and worrying safety. MoS2 is considered to be a competitive anode material that exhibits large capacity due to its unique layered structure for cation insertion/extraction. Nevertheless, the sluggish reaction kinetics of MoS2 does not match the cathode side, which makes the constructed full DIBs show poor rate ability. Here, a flower-like MoS2/ polyaniline composite electrode (MoS2-PANI) where PANI was grown in situ between layers of MoS2 nanosheets was designed. In this design, the inserted PANI can broaden the layer distance of MoS2 to facilitate cation diffusion and prevent the restacking of nanosheets. Furthermore, PANI is also expected to increase the conductivity and relieve the volume changes during repeated charge/discharge cycles. Benefiting from that, the MoS2-PANI electrode delivered a reversible capacity of 561.91 mA h g–1 at 5 A g–1 in half-cell test. Moreover, when coupled with a mildly expanded graphite (MEG) cathode, the obtained MEG//MoS2-PANI DIB shows excellent rate ability with a reversible discharge capacity of 86.62 mA h g–1 and a desirable energy density of 308.83 W h kg–1 at 20 C. These results provide some inspiration for the design of high-rate DIBs.

High power and energy density of a wavy PCM unit embedded in a solar air heater utilizing fractional porous media

This experimental and numerical investigation presents the optimization of a wavy PCM unit to obtain high power and energy density with and without porous media for solar air heater applications at low ambient temperature (12oC≤Ta≤24oC). Hence, paraffin wax as a thermal energy storage material and wire mesh as a porous media are selected in this investigation. The effect of the fractional porous region (25%≤ψ≤100%) and porosity (94%≤ϕ≤100%) of the PCM unit is investigated to obtain desired power and energy density. The obtained numerical results revealed that the porous fraction region (ψ) of 50% and porosity (ϕ) of 96% are the optimum value in wavy PCM unit to obtain high power and energy density. As an extension of this work, the optimized thermal energy storage unit is further utilized in an impinging jet solar air heater design to obtain instant and long thermal backups and, consequently, outlet air at high temperature. The wavy PCM unit embedded impinging jet solar air heater is experimentally investigated under outdoor conditions for two cases; viz, to obtain instant and long thermal backups. To obtain instant and long thermal backups, a full day and alternative operations are conducted. Whereas, in case of alternative operation, charging of the PCM unit is only done up to the maximum sunshine hour of the day and solar air heater is operated during the night to utilize stored thermal energy at high power and energy density to deliver outlet air at high temperature for the long duration. Moreover, the experimental results revealed a maximum outlet air temperature of 59°C at 0.01 kg/s and a significant thermal energy backup up to 5 h at an outlet air temperature gain of ≥ 5°C. The economic analysis is also conducted for the solar air heater design and the operating cost is obtained as 0.02 INR/kWh at the optimum condition.

Routes to Electrochemically Stable Sulfur Cathodes for Practical Li-S Batteries.

Lithium-sulfur (Li-S) batteries have been investigated intensively as a post-Li-ion technology in the past decade; however, their realizable energy density and cycling performance are still far from satisfaction for commercial development. Although many extremely high-capacity and cycle-stable S cathodes and Li anodes are reported in literature, their use for practical Li-S batteries remains challenging due to the huge gap between the laboratory research and industrial applications. The laboratory research is usually conducted by use of a thin-film electrode with a low sulfur loading and high electrolyte/sulfur (E/S) ratios, while the practical batteries require a thick/high sulfur loading cathode and a low E/S ratio to achieve a desired energy density. To make this clear, the inherent problems of dissolution/deposition mechanism of conventional sulfur cathodes are analyzed from the viewpoint of polarization theory of porous electrode after a brief overview of the recent research progress on sulfur cathodes of Li-S batteries, and the possible strategies for building an electrochemically stable sulfur cathode are discussed for practically viable Li-S batteries from the authors' own understandings.

In situ tellurization strategy for crafting nickel ditelluride/cobalt ditelluride hierarchical nanostructures: A leap forward in hybrid supercapacitor electrode materials

Advancements in renewable energy conversion can be significantly propelled by optimizing the performance of transition-metal-based electrodes. In this study, we introduce an innovative, in situ tellurization strategy to synthesize novel, flower-like hierarchical structures of nickel ditelluride/cobalt ditelluride (NiTe2/CoTe2) on a nickel foam substrate (labeled as NF/FNCT), making them promising candidates for electrodes in hybrid supercapacitors. Initially, we utilized a hydrothermal method to create flower-like NiCo-layered double hydroxide (NiCo-LDH) nanoarrays on nickel foam (NF/FNCLDH). This process was followed by the tellurization of these nanoarrays, which yields the NiTe₂/CoTe₂ nanostructures. The strategic assembly of active materials on a conductive substrate effectively obviates the need for inert, slow-conductive binders, thereby facilitating redox chemistry. Capitalizing on the synergistic effects of the conductive tellurium and hierarchical flower-like nanomorphology, the NF/FNCT showcases expedited electron/ion transport, enhanced efficiency, and exceptional electrochemical performance. The NF/FNCT electrode discloses an impressive capacity of 1388.9 (±3) C/g, superior rate capability (83.45 % capacity retention at 30 A/g), and remarkable cycling durability of 96.67 %. Furthermore, when integrated with activated carbon (AC), the resultant hybrid supercapacitor delivers a desirable energy density of 58.85 Wh kg−1 at a power density of 806.85 W kg−1, demonstrating commendable rate capability and cycling durability. This investigation opens new avenues for the synthesis of materials for hybrid supercapacitors.