Battery-type Electrode Research Articles

Effect of Ce-Doping on the Structural, Morphological, and Electrochemical Features of Co3O4 Nanoparticles Synthesized by Solution Combustion Method for Battery-Type Supercapacitors

This study investigates the potential of cerium (Ce) doping to improve the performance of cobalt oxide (Co₃O₄) nanoparticles as battery-type supercapacitor electrodes. Pure Co₃O₄ nanoparticles were synthesized via a solution combustion method and then doped with 2.5% (Ce-Co3O4) and 5% Ce (CeO2-Co3O4). Comprehensive characterization, including X-ray diffraction (XRD), Raman spectroscopy, and field emission scanning electron microscopy (FESEM), was used to analyze the impact of Ce doping on the material properties. XRD analysis confirmed the successful incorporation of Ce into the Co₃O₄ structure, with distinct CeO2 phases forming at higher doping levels. Ce doping resulted in decreased crystallite size and peak intensity, indicating reduced crystallinity and increased defect concentration. Raman spectroscopy corroborated these findings, showing a redshift that suggests weakened metal-oxygen bonds and smaller grain sizes due to Ce³⁺ incorporation. FESEM images demonstrated that Ce doping effectively reduced nanoparticle agglomeration, with 2.5% doping leading to smaller particles and 5% doping promoting a 2D flake-like morphology with increased porosity. Nitrogen adsorption-desorption measurements revealed a significant increase in surface area and pore volume for CeO2-Co₃O₄, facilitating improved electrolyte diffusion and reduced resistance, thereby enhancing electrochemical performance. Evaluation of the electrochemical properties of undoped and Ce-doped Co₃O₄ materials revealed a battery-like response in a three-electrode configuration. Notably, the CeO2-Co3O4 exhibited a superior specific capacity of 603.3 C g-1 at a current density of 1 A g-1, significantly exceeding the values of 368.5 C g-1 and 127.1 C g-1 achieved by Ce-Co3O4 and undoped Co3O4, respectively. Furthermore, the CeO2-doped Co3O4 demonstrated exceptional cyclic stability, retaining 87% of its initial capacity after undergoing 5000 charge-discharge cycles at a high current density of 10 A g-1. These results suggest that Ce doping is a promising strategy for optimizing Co₃O₄-based battery-type electrode materials, potentially leading to the development of high-performance and cost-effective energy storage systems.

Design and fabrication of Bi2S3/Gr composite materials for investigating the performance of hybrid supercapacitors as advanced battery-type electrodes

In the present study, we report the growth of nanorod-shaped bismuth sulfide on the surface of layered graphene, forming a bismuth sulfide/graphene heterostructure. The distinctive architecture significantly amplifies its ion adsorption capacity, thereby endowing the material with outstanding electrochemical performance. The specific capacitance of the Bi2S3 electrode is determined to be 232.1 C g−1 at a current density of 1 A g−1. In contrast, the specific capacity could reach 528.9 C g−1 when Bi2S3 is incorporated with graphene (Bi2S3/Gr-2). Furthermore, the Bi2S3/Gr-2 demonstrates an impressive cycling life retention rate of 85.5 % during a stability test of 10,000 cycles at a high current density (10 A g−1). In contrast, the pure Bi2S3 only achieves a retention rate of 67.4 %. In a hybrid supercapacitor system, the positive electrode consists of Bi2S3/Gr, while activated carbon (AC) serves as the negative electrode. The optimal energy density values can reach up to 39.36 Wh kg−1 at a power density of 800.09 W kg−1, while maintaining excellent stability with a capacity retention rate of 97.5 % after undergoing 10,000 cycles at high current density. This study emphasizes the importance of advanced electrode materials for electrochemical energy storage and the conclusions，which offer crucial insights into the development of metal sulfides/graphene composite materials and their electrochemical performance.

Battery-Type Desalination Behavior Confined Within Capsules for Efficient Capacitive Deionization.

Battery-type faradaic materials are considered a class of promising electrodes for capacitive deionization (CDI) due to their superior ability to store ions through redox reactions. However, the desalination potential of such electrode materials has not been fully explored subject to the accessibility, conductivity, stability, etc. Herein, embedded battery material Ag nanoparticles is designed in capsule-structural units composed of graphene and constructed freestanding composite electrodes for CDI. Particularly, these Ag nanoparticles confined in interconnected graphene capsules can be both efficiently accessed by the electrolyte and rationally protected by the capsule networks, significantly unlocking their potential as desalination materials. Impressively, the optimized Ag-involved anodes can achieve an ultrahigh NaCl desalination capacity of ≈360 mg g-1 (≈218 mg g-1 for Cl-) at 1.4 V and exhibit good cycling stability. Moreover, the as-designed anodes also have very competitive desalination capacities for other anions, such as SO2- 4 (≈90 mg g-1) and CrO2- 4 (≈77 mg g-1), suggesting the broad applicability of such Ag-involved electrodes. This work shows that the ingenious introduction of space-confined structures is an effective means of unlocking the desalination potential of Ag-based materials, opening up alternative avenues for the development of other high-performance battery-type desalination electrodes.

Synthesis of CuS and CuS/C-150 for application in battery type electrode and analysis via electrochemical impedance spectroscopy

Synthesis of CuS and CuS/C-150 for application in battery type electrode and analysis via electrochemical impedance spectroscopy

Solid-state preparation of in-situ grown graphene-embedded bi-metallic NiMnS hybrids for high-performance asymmetric supercapacitor

Endowed with intrinsic redox-rich features and superior electronic conductivities, mixed-metallic sulphides offer high prospects in electrochemical charge storage, especially in supercapacitors. Hence, their rational design and scalable preparation are of great scientific significance. Herein, we report the in-situ growth of nanostructured hybrids of NiMnS directly embedded into graphene sheets by a straightforward, scalable solid-state synthesis method. In this environment-friendly approach, the metal precursors, elemental sulphur, and graphene oxide (GO) are homogeneously mixed under ball-milling, followed by controlled thermal treatment. Incited from their unique synergistic contribution, the resulting NiMnS/G hybrids exhibit impressive electrochemical performance as a battery-type electrode in an aqueous electrolyte. The NiMnS/G hybrid electrode displayed a high specific capacity of 871.7C g−1 at 2 A g−1 with superior rate capability. Moreover, the asymmetric supercapacitor (ASC) device assembled based on the surface-enhanced NiMnS/G nanohybrid as the positive electrode and activated carbon (AC) as the negative electrode achieves an intriguing performance, delivering a maximum energy density of 53.4 Wh kg−1 at a power density of 500 W kg−1. The ASCs were successfully cycled over 10,000 cycles with 87 % capacitance retention and around 99 % Coulombic efficiency. This simple yet scalable strategy holds high promise and may pave the way for preparing other multimetallic sulphide-based hybrid electrode materials for electrochemical energy storage applications.

Monitoring the synergistic effect of Mn/Ni Co-doping and morphological engineering in α-Fe2O3 for energy storage capacity as battery type electrode material

Morphology engineering and elemental doping proved to be an efficient way to enhance the capacitive performance of electroactive materials. To investigate the tuning of morphology via doping here, pure α-Fe2O3 and Ni1-xMnxFeO3+δ (x = 0,0.3,0.5,0.7,1) was synthesized via the hydrothermal method and investigated the impact of Ni and Mn doping on the structural, morphological, and electrochemical properties of α-Fe2O3. The XRD and Raman spectra confirmed the single-phase hematite's rhombohedral crystal structure of pure α-Fe2O3 with no extra peaks confirming the Ni and Mn doping without impurities. SEM analysis demonstrated a shift in the morphology of nanostructures, from spherical to nano-rod structures with increasing the concentration of Mn doping. Cyclic voltammetry results unveiled the battery-type behavior of Ni1-xMnxFeO3+δ nanoparticles while GCD results indicated an escalation in specific capacity from 380 Cg-1 (706 Fg-1) to 751 Cg-1 (1251 Fg-1) with higher Mn content. This increase culminated in the highest specific capacity of 751 Cg-1 (1251 Fg-1) for α-MnFeO3 +δ nanoparticles at the current density of 1 Ag-1 which is higher than α-Fe2O3 (380 Cg-1), NiFeO3+δ (425 Cg-1), Ni0.7Mn0.3FeO3+δ (470 Cg-1), Ni0.5Mn0.5FeO3+δ (530 Cg-1), and Ni0.3Mn0.7FeO3+δ (590 Cg-1). In addition, α-MnFeO3+δ exhibited a remarkable charge capacity retention (96%), and 100% coulomb efficiency after 10,000 consecutive GCD cycles. The noteworthy specific capacity and robust stability of the α-MnFeO3+δ nanorods suggest their suitability as potential candidates for battery type supercapacitors.

Insights of oxygen vacancies engineered structural, morphological, and electrochemical attributes of Cr-doped Co3O4 nanoparticles as redox active battery-type electrodes for hybrid supercapacitors

The global warming issue is spurring the development of renewable energy solutions, where supercapacitors are emerging as promising options for energy storage. Despite advancements in battery-type materials, doping is a practical approach to enhancing electrochemical performance. In this study, using the solution combustion method, we synthesized spinel Co3O4 nanoparticles doped with chromium (Cr) at 2.5 % and 5 % concentrations. The addition of Cr significantly modifies the structural, morphological, surface, and electrochemical properties of Co3O4 nanoparticles. Raman and X-ray photoelectron spectroscopy confirm that this doping method effectively regulates the oxygen vacancy defect level. Moreover, Cr dopants and oxygen vacancies modify electronic states, facilitating more accessible contact to active sites, improving electrical conductivity and more intricate redox chemistry. Notably, the 2.5 % Cr-doped Co3O4 configuration demonstrates substantially enhanced specific capacity (334.64 C g−1/92.95 mAh g−1 at 1 A g−1) and rate performance (59 %), surpassing those of 5 % Cr-doped Co3O4 and undoped Co3O4. Furthermore, the as-fabricated 2.5 % Cr-doped Co3O4//activated carbon (AC) hybrid supercapacitor (HSC) device exhibits a noteworthy energy density of 42.5 Wh kg−1 at 1295.73 W kg−1, withstanding 33.54 Wh kg−1 even at a power density of 5720.46 W kg−1. The HSC device showcases outstanding cyclic performance with 100 % capacity retention after 5000 cycles. Therefore, our work offers a viable way to improve the efficiency of hybrid supercapacitors by providing essential insights into the design of defect-engineered battery-type electrode materials.

Theoretical and experimental studies on 2D β-NiS battery-type electrodes for high-performance supercapacitor

Recently, quirky features and eccentric structures of transition metal sulfides have grasped great attention to remove roadblocks and unwrap fresh avenues for electrodes in energy storage devices. Herein, we developed a 2D beta phase nickel sulfide nanosheets (2D β-NiS NSs) electrode with remarkable enhancement in charge storage properties. When served as active electrodes for electrochemical tests, 2D NiS NSs exhibited ultra-high capacitance of 2693 Fg−1 at 1 mVs−1 and specific capacity of 219 mAhg−1 at 1 Ag−1. The symmetric battery type solid-state supercapacitor device comprising 2D β-NiS NSs electrodes exhibits specific capacity of 83.43 mAhg−1at 2 Ag−1 over broad potential range of 0.7V with good cycling performance, and energy and power density of 28.9 Whkg−1 (@ 2 Ag−1) and 21 kWkg−1 (@ 6 Ag−1) respectively. Complementary first-principles density functional theory (DFT) calculations accomplished to explore the electrolyte ion interactions with nickel sulfide nanostructures defining 2D NiS NSs as a potential candidate for real-time applications.

A novel hybrid sodium ion capacitor based on Na [Ni0.60Mn0.35Co0.05] O2 battery type cathode and presodiated D-Ti3C2Tx pseudocapacitive anode

The combination of the high-power density of supercapacitors and the high energy density of batteries makes hybrid sodium-ion capacitors (HSICs) a promising device. HSICs can provide better performance characteristics by harnessing both ion adsorption/desorption in the capacitor-type electrode and sodium-ion intercalation in the battery-type electrode. Here, the synthesis of MXene (Ti3C2Tx), a two-dimensional (2D) carbide and nitride is reported. Delaminated MXene (D-Ti3C2Tx) is a promising candidate for anode material in HSIC due to its large surface area (∼ 42 m2/g) and good electronic conductivity. Electrochemical study indicates that D-Ti3C2Tx anode exhibits a high discharge capacity of ∼213 mAh/g at a current rate of 20 mA/g. Further the presodiated D-Ti3C2Tx anode is paired with Na [Ni0.60Mn0.35Co0.05] O2 (P2-NMC) cathode to obtain the configuration of HSIC. The HSIC exhibits good specific capacitance of ∼187 F/g and specific discharge capacity of ∼110 mAh/g at a current density of 10 mA/g, according to the electrochemical analysis. A notable improvement in specific energy density (∼ 256 Wh/kg) and specific power density (∼579 W/kg) is also demonstrated by the HSIC. With P2-NMC being used as the cathode material rather than traditional activated carbon, there has been a rise in specific energy density.

Improving energy density of battery-type electrode material by growing β-Ni(OH)2 in situ on biochar for hybrid supercapacitors

The insufficient energy density of electrode materials has hindered the popularity and application of supercapacitors. The construction of hybrid supercapacitors offers an ideal solution by combining transition-metal hydroxides with high specific capacity and biochar with excellent conductivity. In this study, an electrode material (β-Ni(OH)2@AC22 composite) was created by in situ growth flower-like β-Ni(OH)2 nanosheets on biochar (AC) that extracted from the seed coat of Xanthoceras sorbifolium Bunge. This β-Ni(OH)2@AC22 composite exhibited a remarkable specific capacity of 617.5C g−1 (1 A g−1), nearly four times that of AC, and remarkable cycling stability (85.6 % retention after 5000 cycles). Using this composite as the positive electrode and biochar as the negative electrode, the assembled battery-type hybrid supercapacitors (HSCs) achieved a specific capacity of 92.75C g−1 (1 A g−1). The HSCs demonstrated a specific energy of 57.9 Wh kg−1, a specific power of 750.9 W kg−1, and even maintained 42.2 Wh kg−1 at a maximum specific power of 6049.4 W kg−1. The device maintained a specific capacity of about 78.7 % after 7000 charging/discharging cycles, demonstrating good practical performance. These results highlight the practical application potential of the prepared composites in supercapacitors, with biochar serving as a basis for enhancing the electrochemical performance of supercapacitors.

Boosting Zn-Ion Storage Behavior of Pre-Intercalated MXene with Black Phosphorus toward Self-Powered Systems.

MXene-based Zn-ion capacitors (ZICs) with adsorption-type and battery-type electrodes demonstrate high energy storage and anti-self-discharge capabilities, potentially being paired with triboelectric nanogenerators (TENGs) to construct self-powered systems. Nevertheless, inadequate interlayer spacing, deficient active sites, and compact self-restacking of MXene flakes pose hurdles for MXene-based ZICs, limiting their applications. Herein, black phosphorus (BP)-Zn-MXene hybrid is formulated for MXene-based ZIC via a two-step molecular engineering strategy of Zn-ion pre-intercalation and BP nanosheet assembly. Zn ions as intercalators induce cross-linking of MXene flakes with expandable interlayer spacing to serve as scaffolds for BP nanosheets, thereby providing sufficient accessible active sites and efficient migration routes for enhanced Zn-ion storage. The density functional theory calculations affirm that zinc adsorption and diffusion kinetics are significantly improved in the hybrid. A wearable ZIC with the hybrid delivers a competitive areal energy of 426.3µWhcm-2 and ultra-low self-discharge rate of 7.0mVh-1, achieving remarkable electrochemical matching with TENGs in terms of low energy loss, matched capacity, and fast Zn-ion storage. The resultant self-powered system efficiently collects and stores energy from human motion to power microelectronics. This work advances the Zn-ion storage of MXene-based ZICs and their synergy with TENG in self-powered systems.

Binder-free copper manganese sulfide nanoflake arrays electrodeposited on reduced graphene oxide-wrapped nickel foam as an efficient battery-type electrode for asymmetric supercapacitors

In the current study, 2D interconnected copper manganese sulfide (CMS) nanoflake arrays are successfully electrodeposited on nickel foam (NF) and reduced graphene oxide-coated NF (NF/rGO). A pulsed current electrodeposition method is used to prepare a uniform and homogeneous coverage of rGO on NF. By using rGO as a conductive carbon-based template, an ultrathin nanoflake structure of CMS with smaller dimensions and higher electrochemically active surface area (ECSA) is achieved. The results reveal the battery-type behavior of the as-synthesized CMS electroactive materials. At a current density of 5 A g−1 this electrode delivers a significant specific capacity of 667 C g-1 and maintained a considerable proportion of its initial capacity, with a retention value of 83.2 % even after undergoing 3000 charge/discharge cycles. In addition, an asymmetric supercapacitor is fabricated by setting up the synthesized NF/rGO/CMS sample as the positive electrode and activated carbon as the negative electrode. The constructed device not only delivers an impressive energy density of 63.3 Wh kg-1 accompanied by an outstanding power density of 11214.5 W kg−1, but also exhibits a considerable cycling durability, enduring only a 12 % decline in specific capacitance after 3000 charge/discharge cycles at a current density of 5 A g−1.

A Combined Insertion-Conversion Process in Graphite: CuO Composite Enhances the Energy of Lithium-Ion Capacitors with Wide Operational Temperatures

Lithium-ion capacitors (LICs) are prime energy storage devices that meet the limitations of Lithium-ion batteries (LIBs) and Electrical double-layer capacitors, bringing energy and power simultaneously in a single device. Our LIC comprises a combined insertion-conversion mechanism in the battery-type electrode, and the cathode is the commercially available activated carbon. The conversion-type CuO and intercalation-type graphite were mixed uniformly via a mechanical planetary miller and used directly as the anode material. It is noteworthy to mention that the CuO and graphite were regenerated/recovered from the spent LIBs. The copper foil current collector of spent LIB was regenerated as the CuO using simple steps, and the graphite was recycled directly. Five different composites were prepared, and an electrochemical comparative study was performed among these composites. In addition, the performances were compared between two different binders: Polyvinylidene fluoride (PVdF) and Carboxymethylcellulose (CMC), in which the dominance of CMC was significantly observed. The Li-ion storage properties were investigated by pairing the composites with the Li-metal. All the composites exhibited better electrochemical performance in half-cell assembly. The interfacial properties, such as Solid Electrolyte Interface formation/depletion, were studied from the in-situ-impedance. The LIC fabricated, with prior pre-lithiation, exhibited an enhanced energy density of 175 Wh kg–1 with excellent cyclic stability for more than 10,000 cycles. The LIC was also adaptable to different climatic conditions as it was analysed by testing the electrochemical performance at various temperature conditions. Figure 1

All-in-All: Dead Lithium-Ion Battery to Active Lithium-Ion Capacitor.

Here, we have developed lithium-ion capacitors (LICs) with all the components, except the electrolyte solution, effectively recycled from the spent Lithium-ion batteries (LIBs). Hybrid capacitors, such as LICs, are potential breakthroughs in electrochemical energy storage devices, where most research is focused. These devices can simultaneously guarantee high energy and power by hybridizing battery-type and capacitive-type electrodes with two different reaction mechanisms. We have successfully upcycled the graphite, current collector, separator, etc., from the spent LIBs to fabricate a high-performance LIC. Our LIC consists of recovered graphite (RG) coated over recovered copper foil as an anode, recycled polypropylene as the separator, and reduced graphene oxide (rGO) synthesized from RG as the cathode. The RG half-cell exhibited an excellent specific capacity of 302 mAh g-1 even after 75 charge-discharge cycles with a coulombic efficiency of >99 %. The Li/rGO displayed remarkable cycling performance for over 1000 cycles with high stability and reversibility. Subsequently, the pre-lithiated RG (p-RG) electrode is paired with the rGO electrode under the balanced loading conditions to construct LIC, rGO/p-RG, delivering a maximum energy density of 185 Wh kg-1 with ultra-long durability of more than 10,000 cycles. The possibility of LIC under different climatic conditions is also explored, and its remarkable performance under various temperature conditions is worth mentioning.

Tailoring d-p Orbital Hybridization to Decipher the Essential Effects of Heteroatom Substitution on Redox Kinetics.

The heteroatom substitution is considered as a promising strategy for boosting the redox kinetics of transition metal compounds in hybrid supercapacitors (HSCs) although the dissimilar metal identification and essential mechanism that dominate the kinetics remain unclear. It is presented that d-p orbital hybridization between the metal and electrolyte ions can be utilized as a descriptor for understanding the redox kinetics. Herein, a series of Co, Fe and Cu heteroatoms are respectively introduced into Ni3Se4 cathodes, among them, only the moderate Co-substituted Ni3Se4 can hold the optimal d-p orbital hybridization resulted from the formed more unoccupied antibonding states π*. It inevitably enhances the interfacial charge transfer and ensures the balanced OH- adsorption-desorption to accelerate the redox kinetics validated by the lowest reaction barrier (0.59 eV, matching well with the theoretical calculations). Coupling with the lower OH- diffusion energy barrier, the prepared cathode delivers ultrahigh rate capability (~68.7 % capacity retention even the current density increases by 200 times), and an assembled HSC also presents high energy/power density. This work establishes the principles for determining heteroatoms and deciphers the underlying effects of the heteroatom substitution on improving redox kinetics and the rate performance of battery-type electrodes from a novel perspective of orbital-scale manipulation.

Hierarchical Two-Dimensional Layered Nickel Disulfide (NiS2)@PEDOT:PSS Nanocomposites as Battery-Type Electrodes for Battery-Type Supercapacitors with High Energy Density

Hierarchical Two-Dimensional Layered Nickel Disulfide (NiS2)@PEDOT:PSS Nanocomposites as Battery-Type Electrodes for Battery-Type Supercapacitors with High Energy Density

Novel ferrocene-based graphene oxide/Polypyrrole nanocomposites: Electro-capacitive properties study

In this research, we fabricated two novel ferrocene-modified graphene oxide (GO) nano-hybrids as electrode material for supercapacitors. Particularly, the physicochemical interaction of GO surface functional groups and as-synthesized ferrocenyl derivative, along with physical addition of polypyrrole (PPy) resulted in the preparation of high-performance battery-type capacitive materials. The GO-FBF1/PPy, and GO-FBF2/PPy, as final nanocomposites exhibited 229.43 and 269.57 mAhg−1 charge storage capacity, and capacity retention of 91 % and 93 % over 5000 CV cycles, respectively. Also, a symmetric supercapacitor (SSC) with GO-FBF2/PPy as both the anode and cathode exhibits exceptional cycling performance, with 95 % of its capacity remaining after 3000 cycles, and can be operated in a broad electrochemical window up to 1.6 V. Furthermore, our SSC device shows remarkable power and energy densities of 7859 W kg−1 and 123 Wh kg−1, respectively. For high-performance SCs, this research offers a way to improve the electrochemical characteristics of redox-active battery-type electrode materials.

Polyoxometalate/MOF-derived MoSe2/(Ni, Co)Se2 for battery-type electrodes of high-performance supercapacitors

Polyoxometalates (POMs), as multinuclear metal oxide clusters, possess natural multi-electron redox properties and high electrical conductivity. However, their susceptibility to leaching and agglomeration limits their application in energy storage. MOF materials provide a solution to the limitation of POMs due to their controllable pore sizes, big surface areas and strong adsorption properties. The synergistic effect between the two components greatly improves the electrochemical properties of the composites. In view of this, PMo12 is encapsulated in ZIF-67 to form PMo12@ZIF-67 by in situ self-assembly, and benefitted from this unique precursor, MoSe2/(Ni, Co)Se2 hollow structures assembled by nanoparticles are synthesized though Ni2+ etching and selenization process. At the same time, the PMo12 content is optimized to get the best performance of 60-MoSe2/(Ni, Co)Se2. In the three-electrode test, the developed 60-MoSe2/(Ni, Co)Se2 electrode material exhibits an excellent specific capacity of 359.9 mA h g−1 at a current density of 1 A g−1, and a capacitance retention rate of 83.7 % after 10,000 cycles. In addition, the asymmetric supercapacitor (ASC) assembled with a positive electrode of 60-MoSe2/(Ni, Co)Se2 and a negative electrode of activated carbon exhibits an excellent energy density of 40.3 W h kg−1 at a power density of 800.9 W kg−1. These superior electrochemical properties are attributed to the unique electronic structure of PMo12, which further demonstrates the feasibility of constructing hollow multicomponent selenides as energy storage materials using PMo12-ZIF-67 as a precursor.

Comprehensive characterization of octahedral Co3O4 doped with Cu induces oxygen vacancies as a battery-type redox active electrode material for supercapacitors

The urgent need to combat global warming has spurred the exploration of renewable energy solutions, among which the supercapacitor has emerged as a promising contender for efficient energy storage in crucial applications. While battery-type electrode materials (BTMs), notably Co3O4, have shown impressive electrochemical performance in recent years, their inherent limitations, such as low conductivity, restricted surface area, and suboptimal electrochemical activity, pose challenges to their utility. Doping has emerged as a strategic solution to address these issues by modifying the crystal structure, surface morphology, specific surface area, electronic conductivity, and chemical stability of the host material, thereby enhancing its electrochemical performance. This study uses a combustion synthesis method to engineer octahedral Co3O4 with Cu-doping. We obtained three different samples of Co3O4: one undoped Co3O4, doped with 3 % Cu (3%Cu–Co3O4), and 6 % Cu (6%Cu–Co3O4). The addition of Cu not only changed the crystal structure and surface morphology but also impacted the surface area and defects (oxygen vacancies) in Co3O4, affecting its electrochemical performance. This doping method effectively controlled the oxygen vacancy defect content, as verified meticulously by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). Particularly, the 6%Cu–Co3O4 configuration demonstrated significantly improved specific capacity (155.5 mA h g−1/559.8C g−1 at 1 A g−1) and rate performance (67 %), outperforming both 3%Cu–Co3O4 and undoped Co3O4. Additionally, it exhibited superior cycling stability with 91 % retention of the maximum specific capacity after 5000 cycles. Consequently, this study offers valuable insights into designing defect-engineered battery-type electrode materials for hybrid supercapacitors, which could significantly enrich their efficiency.

Convenient room-temperature synthesis of sulfur and nitrogen co-doped NiCo-LDH coupled with CNTs on NiCo foam as battery-type electrode for high performance hybrid supercapacitor

Convenient room-temperature synthesis of sulfur and nitrogen co-doped NiCo-LDH coupled with CNTs on NiCo foam as battery-type electrode for high performance hybrid supercapacitor