Electrode Materials Research Articles

Layered double hydroxide assembled on a metal–organic framework coupled with polyaniline as pseudocapacitive anode for phosphorus capture

Excessive phosphorus is detrimental to supporting the proper function of aquatic ecosystems. Capacitive deionization (CDI) is an emerging, highly efficient, eco-friendly electrochemical technology that eliminates phosphorus from wastewater. In this work, a novel LDH@MOF/PANI composite was successfully fabricated by utilizing polyaniline (PANI) as a conductive substrate and metal–organic framework (MOF) as a self-sacrificial template for layered double hydroxide (LDH). The results demonstrated that LDH and PANI are favorable for improving the pore structure features, enriching the phosphorus binding sites, and strengthening the electrochemical performance of the electrode materials. Accordingly, the LDH@MOF/PANI electrode presented a superior phosphorus capture capacity than LDH@MOF and MOF. The isotherm and kinetic experiments revealed that the phosphorus capture by LDH@MOF/PANI is a chemisorption-dominated process associated with heterogeneous adsorption. The potential interference with phosphorus uptake was also assessed by focusing on several vital factors. Eventually, the possible mechanism suggested that ligand exchange, anion exchange, hydrogen bond, electrostatic attraction, and electric field assistance participate in the phosphorus uptake process. This work presents promising insight into the assembly design and rational construction of LDH-based pseudocapacitive anode for phosphorus capture.

Fabrication of functional laser-induced graphene using gelatin-2,6-diaminoanthraquinone coating for high-performance micro-supercapacitor

In this investigation, we develop a procedure in which gelatin and 2,6-diaminoanthraquinone (ANQ) are combined and then applied as a coating on laser-induced graphene (LIG). The resulting materials are subjected to laser irradiation, which facilitates the introduction of nitrogen doping and the integration of oxygenated functional groups onto the LIG surface. The gelatin polymer played a pivotal role in introducing oxygenated functional groups, while ANQ molecules contributed to both doping with nitrogen and the inclusion of additional oxygenated groups on the LIG surface. The electrode material's performance was enhanced by these functional groups. When evaluated in a three-electrode setup, the ANQ-LIG configuration exhibited a significantly high areal capacitance of 32.4 mF cm−2 at 0.2 mA cm−2, which is five times that of pristine LIG (6.3 mF cm−2) and three times that of gelatin-LIG (9.0 mF cm−2). When integrated into a micro-supercapacitor using a polyvinyl alcohol (PVA)-sulfuric acid (H2SO4) gel electrolyte, ANQ-LIG demonstrated superior areal capacitance (16.0 mF cm−2 at 0.1 mA cm−2) compared to gelatin-LIG (5.3 mF cm−2) at the same current. Additionally, ANQ-LIG displayed favorable capacitance retention (83.8 % after 10,000 cycles) and coulombic efficiency (98.1 % after 10,000 cycles).

Green synthesis of CoVS2-MOF@CMS nanocomposite electrode for sustainable approach towards eco-friendly energy storage and dopamine detection

Dopamine, a crucial brain chemical belonging to the catecholamine and phenethylamine chemical families, plays a vital role in promoting a healthy and happy life. Irregular dopamine release has been linked to various neurological disorders and depressive conditions. Therefore, conducting real-time, in vivo monitoring of dopamine levels is essential to gain a comprehensive understanding of its physiological functions. In this research, the hydrothermal technique was employed to synthesize copper‑molybdenum sulfide (Cu2MoS4 (CMS)). Further, we have reported the one-pot hydrothermal synthesis of CoVS2-MOF, using the bioactive chemical as fuel obtained from Euphorbia cognata Boiss. The specific capacity (Qs) of the sample CoVS2-MOF@CMS was calculated to be 820 Cg−1 at 3 mVs−1, a value expressively higher than that of the reference samples. Furthermore, in the supercapattery device, an outstanding Qs of 300 Cg−1 was achieved at 1.5 Ag−1, surpassing the previously observed values. The device demonstrated outstanding performance, including a coulombic efficiency of 89 %, a specific energy of 36.68 Whkg−1, and a power density (Pd) of 2218.53 Wkg−1. Moreover, the sensor typically yielded dopamine (DA) concentrations in human serum ranging from 100.8 % to 102.2 %. The utilization of the multifunctional CoVS2-MOF@CMS nanocomposite electrode material illustrates promising prospects for the fabrication of hybrid devices with applications in biomedical and energy harvesting fields.

Multifunctional applications of novel copper magnesium vanadate nanoparticles: Photocatalytic dye degradation and electrochemical properties

The multifunctional applications of nanomaterials in energy saving, electrochemical energy storage, and sensing devices are a current research trend. Novel Copper Magnesium Vanadate (CMV-CuMg2V2O8) nanoparticles have been synthesized by solution combustion method. The crystallite size calculated from XRD and TEM results was found to be 21 nm. The band gap estimated from UV–Vis DRS of CMV nanoparticles was found to be 3.82 eV. Its multifunctional applications were explored through for energy conversion, storage and sensing applications. Photocatalytic degradation of Acid Red-88 (AR-88) dye was conducted using CMV nanoparticles as photocatalyst under UV light. CMV nanoparticles modified carbon paste electrodes were prepared and its cyclic voltammetry (CV), Electrochemical impedence spectroscopy (EIS) and Galvanostatic charge–discharge (GCD) analysis were carried out using 1M KCl and NaOH electrolyte. With excellent specific capacitance of 266 Fg−1 in KCl electrolyte and 242 Fg−1 in NaOH electrolyte at 5 mV/s scan rate, CMV NPs was demonstrated to be a promising electrode material for supercapacitors. Electrochemical sensing analysis was carried out using the same electrode for the detection of paracetamol and ibuprofen within the range of 1–5 mM. The resulting copper magnesium vanadate nanoparticles have been verified as a possible electrode material for next-generation energy storage devices.

Efficient electrochemical removal of ammoniacal nitrogen from livestock wastewater: The role of the electrode material

Wastewater from livestock farms contains high concentrations of suspended solids, organic contaminants, and nitrogen compounds, such as ammoniacal nitrogen. Discharging livestock effluents into water bodies without appropriate treatment leads to severe environmental pollution. Compared to conventional treatment methods, electrochemical oxidation exhibits higher nitrogen removal efficiencies. In the present work, the electrochemical removal of ammoniacal nitrogen from real livestock wastewater was investigated through a lab-scale reactor. Preliminary experiments were carried out to investigate the effects of different anode materials, including boron-doped diamond and iridium/ruthenium-coated titanium, on the total nitrogen removal efficiency using synthetic wastewater. Boron-doped diamond, a well-known non-active electrode, allowed to obtain 63.7 ± 1.21 % of total nitrogen degradation efficiency. However, the iridium/ruthenium-coated titanium electrode, belonging to the class of active anodes, showed a higher performance, achieving 78.8 ± 0.76 % contaminant degradation. Coupling iridium/ruthenium-coated titanium anode with a stainless-steel cathode improved the performance of the system, achieving even 96.2 ± 2.73 % of total nitrogen removal. The optimized cell configuration was used to treat livestock wastewater, resulting in the degradation of 67.0 ± 2.25 % of total nitrogen and 37.3 ± 0.68 % of total organic carbon when sodium chloride was added. At the end of the process, the ammonium content was completely removed, and only 17.7 ± 0.51 % of the initial nitrogen turned into nitrate. The results show that the proposed system is a promising approach to treating livestock wastewater by coupling high contaminant removal efficiencies with low operational costs. Anyway, further studies on process optimization with an emphasis on power requirements and electrode costs need to be carried out.

In-situ assembly of 3D VS2/Reduced graphene oxide with superior lithium ion storage performance: The role of heterojunction

VS2 is a potential anode material for lithium-ion batteries (LIBs) due to its advantageous properties. Herein, a novel three-dimensional (3D) VS2/reduced graphene oxide (rGO) heterostructure (VS2-rGO) was fabricated by in-situ assembly of caterpillar-like VS2 nanosheets on rGO. This 3D VS2-rGO with a well-defined heterojunction interface is engineered to mitigate the volumetric expansion of VS2 during Li + intercalation/deintercalation cycles. This optimized design promotes enhanced conductivity across the heterojunction, facilitating efficient electron and ion transport. The VS2-rGO electrode shows higher reversible capacity and better rate performance (644.02 mA h g−1 at 0.1 A g−1 after 140 cycles, 526.66 mA h g−1 at 2 A g−1) as compared to the pure VS2 electrode (433.69 mA h g−1 at 0.1 A g−1 after 140 cycles, 63.91 mA h g−1 at 2 A g−1). Ex-situ XRD analysis suggests that the Li + storage mechanism in the VS2-rGO electrode involves the initial intercalation, followed by intercalation and conversion. The lower Li + diffusion barrier within the VS2-rGO heterojunction (0.183 eV) compared to the VS2 layers (0.225 eV), as predicted by first-principles calculations, resulting the enhanced Li + transport kinetics and improved cycling performance of the VS2-rGO electrode material. This work offers novel perspectives for the influence of heterojunctions on LIBs.

Comparative electrochemical properties of MO (ZrO2, V2O5) based polyaniline nanocomposites for high-performance supercapacitor applications

Due to its distinctive qualities, such as its moderate energy density, extended service life, rapid discharge–charge rates, and superior safety, supercapacitors (SCs) are gaining more and more attention. A zirconium oxide ZrO2 (Zr) and vanadium oxide V2O5 (VO) based PANI nanocomposites, denoted as (ZrP for ZrO2/PANI, and VOP for V2O5/PANI) are fabricated using hydrothermal technique in this research work. Morphological and phase investigations validated the random particle shapes with good crystallinity and purity of the samples. The N2 sorption/desorption isotherm reveals a mesoporous feature of the electrodes and the highest BET surface area (36.5 m2/g) with large electroactive sites, which offers abundant faradaic reactions for charge storage. The I-V characteristics confirm their excellent conduction capabilities as well. When utilized as electrodes for SCs in the three-electrode setup, the VOP composite electrode attains the highest capacitance of 1372 F g−1 at a scan rate of 5 mV s−1 compared with other active electrodes. Besides that, the VOP electrodes offer superior cyclic stability, with a retention rate of 94.28% even after 7000 consecutive charge/discharge cycles. It has been discovered that the in two electrode VOP asymmetric device exhibited remarkable specific capacitance of 651.36 Fg−1 at 5 mV s−1 demonstrating a significant capacitance retention of 87.6% over 6000 cycles. The results suggest that the material could be a good contender for electrode materials in supercapacitors.

NiCoP@amorphous carbon composites with 3D core-shell structure for high-performance asymmetric supercapacitors

In this paper, a facile bio-templating method is proposed to prepare NiCoP coated on amorphous carbon (NiCoP@AC) composite electrode materials with using bagasse as template and carbon source. NiCoP nanowire network arrays precursors coating on bagasse substrate with high yield were prepared via a novel synthesis strategy utilizing the toluene-water interface reaction process, which subsequently formed as NiCoP@AC composite electrode materials after phosphating process. The assembled core-shell structure attenuated the volume expansion during charging and discharging, additionally, the overall electrical conductivity of the composite was also improved owing to the characteristic of bagasse biochar. The NiCoP@AC electrode exhibited high specific capacitance (1706 F g−1 at 1 A g−1), outstanding rate capability (82.1 % capacity retention from 1 to 20 A g−1) and good cycling stability (retaining 80.0 % capacitance over 5000 cycles). In addition, bagasse biomass activated carbon (BAC) was prepared via a typical alkaline activation process for the use as negative electrode. The as-fabricated NiCoP@AC//BAC supercapacitor displayed a high energy density of 46.2 Wh kg−1 at a power density of 807.3 W kg−1, and an excellent capacitance retention rate (88.5 % after 5000 cycles), suggesting that the as-prepared NiCoP@AC electrode materials have wide application prospects in high-performance supercapacitors.

Recent Advances in Electrolytes for Magnesium Batteries: Bridging the Gap Between Chemistry and Electrochemistry.

Rechargeable magnesium batteries (RMBs) have the potential to provide a sustainable and long-term solution for large-scale energy storage due to high theoretical capacity of magnesium (Mg) metal as an anode, its competitive redox potential (Mg/Mg2+: -2.37 V vs. SHE) and high natural abundance. To develop viable magnesium batteries with high energy density, the electrolytes must meet a range of requirements: high ionic conductivity, wide electrochemical potential window, chemical compatibility with electrode materials and other battery components, favourable electrode-electrolyte interfacial properties and cost-effective synthesis. In recent years, significant progress in electrolyte development has been made. Herein, a comprehensive overview of these advancements is presented. Beginning with the early developments, we particularly focus on the chemical aspects of the electrolytes and their correlations with electrochemical properties. We also highlight the design of new anions for practical electrolytes, the use of electrolyte additives to optimize anode-electrolyte interfaces and the progress in polymer electrolytes.

Comparison between Electropolymers of 3,5-Dihydroxybenzoic Acid and 2',6'-Dihydroxyacetophenone in Dimethyl Sulfoxide and Their Analytical Performance towards Selected Analytes with the Role of the Washing Liquid.

In the first part of this study, the electrochemical polymerization of two compounds, 3,5-dihydroxybenzoic acid and 2',6'-dihydroxyacetophenone, was compared in dimethyl sulfoxide solvent on platinum and glassy carbon electrodes. The voltammograms obtained showed remarkable differences between the two monomers and between the two electrode materials. The acetophenone derivative formed electropolymer remnants at the electrodes, while in the case of the benzoic acid derivative, practically no passivation occurred, and the scanning electron microscopic results reinforced this. A few stackings adsorbed only after electropolymerization from a highly concentrated solution of dihydroxybenzoic acid. As a modifying layer on the platinum and glassy carbon electrodes, the prepared films from 2',6'-dihydroxyacetophenone were tested for tributylamine in acetonitrile and in an aqueous solution of a redox-active compound, hydroquinone, during the stirring of the solution. More stable amperometric current signals could be reached with modified platinum than with glassy carbon, and the significant influence of the organic washing liquid after deposition was established via the study of noise level. In this respect, acetone was the best choice. The amperometric signals with the modified platinum obtained upon the addition of aliquots of the stock solution resulted in a 3.29 μM detection limit.

Exploring superconductivity, supercapacitance and thermoelectric properties of NbCr[formula omitted] and its alloys with Li and Mg: A first-principles Investigation

In the present study, the superconductivity, supercapacitance, and thermoelectric properties of the NbCr2 and its alloys with Li and Mg (with alloy composition of x=0.5 in replacement with Cr atoms) have been surveyed using density functional theory. The mechanical, thermodynamic, and dynamic stability of the pure and alloy compositions have been checked by the results of the cohesive energy, enthalpy of formation energy, and phonon density of states. Moreover, the largest value of the critical temperature (Tc) which has been achieved belongs to the pure NbCr2 with a value of 13.76 K. In addition, the largest values of Tc for Li and Mg alloys are 11.83 and 3.42 K, respectively. Furthermore, the largest peak of the quantum capacitance at room temperature and as a function of the applied voltage is also related to the pure NbCr2 with a value of 676.77 μF/cm2 at the voltage of −1.86 V. In addition, the largest value of the surface charge storage occurred at the negative bias of −1.88 V with a value of −1261.27 μC/cm2. For thermoelectric properties, the largest peak of the thermoelectric power factor per relaxation time as a function of chemical potential and at room temperature belongs to Li alloy with a value 20.03 × 1016μW/(m K2 s) at the negative chemical potentials of −0.73 eV. The largest value of electronic thermal conductivity per relaxation time belongs the Li alloy at 500 K with a value of 48.71 × 1014 W/(m K s) and the largest value of lattice thermal conductivity is also related to Li alloy with the value of 22.8 W/(m K) at 100 K. All of these results represent the materials which not only have the superconductivity property but also supercapacitance and thermoelectric properties that could be useful as electrode materials in the energy storage industries.

Synthesis and electrochemical properties of microcanals Mg-S-Cu-S as an electrode material for energy storage applications

The synthesis of novel nanostructured electrode materials is the community demand to overcome energy crises. Herein, the nanostructured copper-sulfide, copper-cadmium-sulfide and copper-magnesium-sulfide (Cu-S, Cd-S-Cu-S and Mg-S-Cu-S) electrodes are synthesized by chemical vapor deposition technique. The changes in crystal growth and surface morphologies of Cu-S, Cd-S-Cu-S and Mg-S-Cu-S electrodes are associated with the formation of heterostructures and change in energy fluxes. The weight % of Ni, Cu, S; Ni, Cd, Cu, S; and Ni, Mg, Cu, S are found to be 8, 62, 30; 6, 16, 48, 30; 15, 14, 45, 26 are observed in Cu-S, Cd-S-Cu-S and Mg-S-Cu-S electrodes respectively. The Mg-S-Cu-S electrode showed superior specific capacitance of 4393 and 5657 F/g at 1 mV/s and 1.0 A/g respectively. The maximum energy density and power density of Mg-S-Cu-S electrode are found to be 141 Wh/kg and 2120 W/kg respectively. The cyclic retention after 3000 cycles of Cu-S, Cd-S-Cu-S and Mg-S-Cu-S electrodes are found to be 80.8, 87.5 and 96.2 % respectively. The simulation results show that the Cd-S-Cu-S followed more capacitive-controlled while Mg-S-Cu-S followed more diffusive controlled process. Result show that the Mg-S-Cu-S electrode is comparatively more suitable for portable energy storage devices.

In-situ repair of failed LiFePO4 cathode using residual Li- and C-containing impurities from active material separation process

Effectively recovering spent lithium-ion batteries can reduce resource waste and environmental pollution. LiFePO4 (LFP) batteries have been widely used in new energy vehicles. The main reason for the performance degradation of LFP cathodes is the loss of Li, oxidation of Fe, and the destruction of crystal structure and surface carbon layer. Here, an in-situ repair strategy of high-temperature calcination, using impurities remaining in cathode blackmass (e.g., LiPF6, LiPO3, Fe2O3, acetylene black, binder, and electrolyte) as raw materials, was proposed. During the calcination process, the residual LiPF6 is converted into Li, acting as a lithium source to fill the vacancies. The residual binder and electrolyte are pyrolyzed into amorphous carbon and carbon nanotubes, which deposit on the LFP particles to repair the missing carbon layer and enhance the conductivity of the electrode material. The pyrolytic carbon and residual acetylene black can provide a reducing atmosphere, converting Fe3+ to Fe2+. Additionally, the residual LiPO3 and Fe2O3 impurities undergo recrystallization forming new LFP. The failed LFP was restored to the same level as commercial LFP by calcining at 750 °C for 3 h. This in-situ repair strategy reduces the input of raw materials, providing a valuable reference for large-scale recycling of lithium batteries.

The regeneration of natural stibnite with introduced oxide-based catalyst towards enhanced Li-storage properties

Owing to its excellent theoretical specific capacity, Sb2S3 captures widespread attention in the energy-storage field. However, it still suffers from volume expansion and sluggish electrochemical kinetics. Meanwhile, considering serious pollution and complex chemical preparation processes, stibnite is regarded as “first-hand” materials, displaying enormous energy-storage application potential; however, it is still limited by low-purity and high crystallinity. Herein, stibnite is purified and regenerated through physical chemical and vacuum gas-phase melting strategy to form high-properties stibnite-based electrode materials. Assisted by the introduction of lithium nitrate as an active medium, abundant sites and effective structural traits are formed, effectively promoting the reversibility of electrochemical kinetic processes. Utilized as lithium-ion battery anodes, the as optimized samples have a capacity of approximately 656.8 mAh g−1 with a capacity retention rate of 89.9 % at 0.5 A g−1. Even at 5.0 A g−1, the capacity of 483.3 mAh g−1 could be remained after 100 cycles. Supported by a detailed kinetic analysis, the enhancement of the surface-controlling behavior and the reduction of capacitive resistance are confirmed. Herein, the as-regenerated phase and the introduced oxide-based catalyst are beneficial to alleviate polysulfide shuttling and volume expansion, further accelerating ion/electron transfer behaviors. This work is expected to shed light on strategies to design promising mineral-based anodes for lithium-ion batteries.

Oriented growth of NiCo metal–organic framework nanosheets on electrode materials for ternary mixed metal oxide supercapacitors

Metal–organic frameworks (MOFs) are porous structures that possess high specific surface areas, making them promising cathode materials for energy storage devices. However, solving the problems of random growth and easy aggregation of MOF nanosheets remains a challenge. In this study, hydrothermal and calcination methods were used to successfully create nickel cobalt molybdenum metal oxide (NCMO) nanoflowers, followed by the directional growth of NiCo–MOF on its surface. The oriented growth of NiCo–MOF nanosheets on NCMO nanospheres effectively prevented agglomeration, forming NCMO@NiCo–MOF with enhanced electrochemical sensitivity and a large quantity of active sites. When used as an electrode, NCMO@NiCo–MOF forms a large contact area with the electrolyte, demonstrating a high specific capacitance of 1724 F g−1 at a current density of 1 A g−1. Furthermore, at a power density of 824.8 W kg−1, an asymmetric supercapacitor constructed from NCMO@NiCo–MOF and activated carbon exhibited a high energy density of 44.5 Wh kg−1. This study presents a facile method for the assembly of MOF nanosheets for three-dimensional supercapacitors.

Self-supported porous carbon decorated with coralline RuCo alloy for efficient OER in acid

Developing an OER electrocatalyst that combines high performance with low cost represents a crucial challenge to address for the widespread adoption and implementation of PEM water electrolyzers. The Ru-based catalyst has garnered significant interest owing to its cost-effectiveness and high activity, positioning it as one of the prime contenders to replace Ir-based catalysts. Nevertheless, Ru-based catalysts are easily corrupted by oxidation at high potential, leading to poor catalyst durability. In this work, we used a simple method to synthesize an electrode material which was a carbon framework-supported coralline RuCo alloy catalyst on the CC surface. The porous and highly conductive carbon framework in RuCo@C/CC effectively anchors the RuCo alloy, preventing its aggregation and detachment from the CC. And the carbon framework also facilitates enhanced mass and charge transfer processes, thereby greatly improving catalytic performance. Additionally, charge transfer and redistribution occur within the RuCo alloy, thereby efficiently reducing the activation energy barrier (via the AEM mechanism) of the OER, consequently enhancing OER performance. Therefore, RuCo@C/CC exhibits outstanding performance in acidic OER, achieving a current density of 10 mA/cm2 at a remarkably low overpotential of 200 mV, significantly surpassing commercial RuO2 (which requires 280 mV), owing to its exceptional OER kinetics, while also demonstrating exceptional stability in practical PEMWE test. This research introduces a convenient route for creating a highly efficient and durable alloy electrocatalyst, showcasing its promise for Proton Exchange Membrane Water Electrolysis.

NiCo layered double hydroxides/carbon dots composites with S-doing for high-performance asymmetric supercapacitors

The pursuit of high-performance electrode materials for supercapacitors has led to the exploration of transition metal layered double hydroxides (LDH), which boast an impressive theoretical specific capacitance. However, their intrinsic limitations, such as poor electronic conductivity and slow diffusion kinetics, have posed significant challenges for their practical implementation. In this work, a NiCo LDH/carbon dots (CDs) composite with S-doping has been meticulously designed to overcome the aforementioned limitations through a synergistic combination of heteroatom doping and carbon incorporation. Utilizing a one-pot hydrothermal method, the composite electrode for the application of asymmetric supercapacitors have been in-situ growth on Ni foam substrate, which not only serves as a robust support but also contributes to the formation of NiCo LDH by providing a uniform Ni source, thereby ensuring strong adhesion and structural integrity. The morphology and microstructures of composites could be finely modulated by adjusting CDs amount. With moderate CDs contents, the optimum electrode S-LDH/CDs-2 exhibits distinctive 3D needle-like spherical morphology, coupled with the ample space for ion diffusion. Consequently, the electrode demonstrates outstanding electrochemical performance, featuring a high areal capacitance of 5157 mF cm−2 at a current density of 2 mA cm−2. Additionally, it exhibits noteworthy rate performance and maintains excellent cycling stability. Integrating the innovative electrode into asymmetric supercapacitors configuration, superior energy density (0.24–0.45 mWh cm−2) and power density (4–20 mW cm−2) as well as good stability have been achieved for the S-LDH/CDs-2//AC device. These results indicate that S-doped NiCo LDH/CDs composite electrode has the desirable potential to be a candidate for energy storage devices.

Exceptional fabrication of dead-weight-free silicon and graphitic heterostructures anodes for the next advancement of Li-ion batteries

Silicon (Si)-graphite and graphite (without Si) anodes for Li-ion batteries are developed at ambient conditions through the direct irradiation of CO2 laser, resulting in avoiding the use of binders, conductive carbon additives, and organic and water-based solvents. Furfuryl alcohol (FA) is mixed with Si-graphite and graphite, prepared viscous slurry through the heating, cast on the copper foil, and dried. Irradiation of CO2 laser at the electrode of Si-graphite-FA generates in-situ hetero-structures of Si particles, SiC/Si-SiC nanowires made of spontaneously carbon-coated/oxidized nano-layer (∼ 3nm), and graphitic carbon containing few layers of graphene. All the laser-fabricated electrode material is electrochemically active (∼ 0% dead weight) in the Si-graphite and graphite anodes since the FA converts to the graphitic carbon containing few layers of graphene; thus, the fabrication method could benefit the next industrial development. The discharge capacity of the Si-graphite electrode with total material loading is recorded at 502.2 mAh/g (∼ 1.9 mAh cm−2) and capacity retention of ∼ 80 % over the 50 cycles vs. Li/Li+. Also, it shows good discharge capacity when fabricated with NMC622 in full-cell format. Therefore, this performance is highly stable without any binder and conductive carbon, especially for Si-based battery, which fails rapidly due to substantial volume changes (∼ 300 %). Moreover, the performance is highly stable for graphite anode with a discharge capacity retention of 91 % over the 160 cycles as considered 100 % (∼ 345 mAh/g) after the formation cycle.

Hollow nickel sources for improving nickel utilization in Zebra batteries

The Zebra (Na-NiCl2) batteries are regarded as a promising option for large-scale electrical energy storage due to their plentiful electrode material resources, high energy density, and safety features. In the cathode of Zebra battery, the nickel powders serve as both an active material and a conductive agent. In practice, its amount is significantly greater than its theoretical usage, often exceeding three times the theoretical amount. Hence, the presence of ultra-excessive nickel results in high material costs, posing obstacles to the wider implementation of Zebra batteries. To address this problem, we introduce hollow nickel source as active material to improve the nickel utilization in Zebra battery. In this work, we assemble Zebra batteries using nickel hollow spheres (NHS) with sizes of ∼200 nm, ∼500 nm, ∼1 μm and ∼ 5 μm as nickel source. The battery using NHSs with a size of 1 μm exhibits the best cycling performance and the lowest polarization voltage. By reducing the Ni(NHS, ∼1 μm)/NaCl mass ratio to 1.0, 60% theoretical capacity can be achieved after 170 cycles at 260 °C, which surpasses the traditional batteries using solid nickel source at the same Ni/NaCl ratio. This performance is comparable to that of traditional solid nickel sources with a mass ratio of 1.5 to NaCl. Therefore, using NHS as the nickel source in Zebra batteries reduces nickel usage by 33% without compromising performance.

Controllable synthesis of NiCoMo-LDH with nanofloral structure assisted by monodisperse spherical silica for asymmetric supercapacitor

Traditional layered double hydroxides (LDH) have disadvantages such as small layer spacing, insufficient active sites and poor electrical conductivity, which seriously restricts their future utilization in the realm of energy storage. In this paper, a controlled synthesis strategy of tercomponent metal NiCoMo-LDH is proposed by using the structural advantages of metal-organic skeleton (MOF) templates, combining structural regulation and atom doping. On the basis of the synthesis of Ni-MOF 74, Co and Mo atoms are introduced for a small amount of doping, and the monodisperse spherical SiO2 is inserted to adjust the pore structure of NiCoMo-MOF, expand the lamellar spacing, and effectively avoid the accumulation and agglomeration of lamella. Finally, NiCoMo-LDH cathode material with loose porous and coarsely curled nanosphere structure was synthesized through the chemical reaction of OH− with SiO2 and the destruction of the skeleton structure of MOF. The specific capacitance of the material is 1423.3 F·g−1 at 0.5 A·g−1, and after 5000 cycles of charging and discharging, 80.0% of the original specific capacitance is sustained. Moreover, NiCoMo-LDH//AC ASC possesses a high energy density of 39.1 Wh·kg−1 at the power density 400 W·kg−1. Combined with density functional theory (DFT) calculation, the fact that metal doping can not only effectively improve the conductivity of electrode materials has been further proved, but also accelerate the electron/ion migration rate, which successfully reveal the synergistic enhancement mechanism of electrochemical properties of materials.