Electrodes For Energy Storage Applications Research Articles

Mesoporous Mn-substituted MnxZn1-xCo2O4 ternary spinel microspheres with enhanced electrochemical performance for supercapacitor applications.

Extensive investigations have been carried out on spinel mixed transition metal oxide-based materials for high-performance electrochemical energy storage applications. In this study, mesoporous Mn-substituted MnxZn1-xCo2O4 (ZMC) ternary oxide microspheres (x = 0, 0.3, 0.5, 0.7, and 1) were fabricated as electrode materials for supercapacitors through a facile coprecipitation method. Electron microscopy analysis revealed the formation of microspheres comprising interconnected aggregates of nanoparticles. Furthermore, the substitution of Mn into ZnCo2O4 significantly improved the surface area of the synthesized samples. The electrochemical test results demonstrate that the ZMC3 oxide microspheres with an optimal Mn substitution exhibited enhanced performance, displaying the largest specific capacitance of 589.9Fg-1 at 1Ag-1. Additionally, the ZMC3 electrode maintained a capacitance retention of 92.1% after 1000 cycles and exhibited a significant rate capability at a current density of 10Ag-1. This improved performance can be ascribed to the synergistic effects of multiple metals resulting from Mn substitution, along with an increase in the surface area, which tailors the redox behavior of ZnCo2O4 (ZC) and facilitates charge transfer. These findings indicate that the incorporation of Mn into mixed transition metal oxides holds promise as an effective strategy for designing high-performance electrodes for energy storage applications.

Biomass waste derived from cassia fistula into value-added porous carbon electrode for aqueous symmetric supercapacitors

Activated carbon derived from biomass sources has been renowned as one of the key materials and economical precursors for numerous energy conversion and storage applications. Herein, we utilized a less explored Cassia fistula (Pulp and seed) biomass as the carbon source for supercapacitor application. Further, a less toxic and low activation method has been implemented to activate the biomass-derived carbon. The highly dense seed resulted in better porous compared to the pulp source. The electrochemical performances of the bio-carbon electrodes have been examined by CV, GCD, and EIS studies. The activated carbon derived from the Cassia fistula seed (CFSA) electrode achieved a specific capacitance value of 136.5 Fg−1 at 0.5 Ag−1 in 3 M KOH. Moreover, the electrode demonstrates an extremely long stability by sustaining 98 % of initial capacitance after 10,000 cycles, which signifies the robust electrochemical stability behavior of the obtained electrode. Further, the aqueous symmetric supercapacitor achieved a maximum energy and power density of 7.2 WhKg−1 and 3488.1 WKg−1, respectively. Likewise, after 10,000 stability cycles, the cell retains 96.4 % capacitance at 5 Ag−1 which denotes the noteworthy capacitive behaviour of the CFSA electrode. Thus, the present work suggests an eco-friendly resource for developing an effectual carbon electrode for energy storage applications.

Development of cost-efficient BaMnO3/rGO nanocomposite as electrode for energy storage applications in supercapacitor

The excessive fossil fuels utilization leads to environment contamination along with energy loss and is becoming a serious issue in these days. Therefore, to handle these energy issues, alternative sources and energy-storing devices like supercapacitors are in demand in the modern era. Many perovskites have been used in supercapacitors as electrode material but because of its less cyclic stability and poor conductivity, rGO mixed to enhance the electrochemical properties of perovskite. Therefore, we used rGO with BaMnO3 to fabricate BaMnO3/rGO nanocomposite through hydrothermal method for supercapacitor electrodes. After different physical analyses, BaMnO3/rGO nanocomposite showed remarkable electrode applications having distinct nanostructure with increased surface area, conductivity, crystallinity and improved morphology. The electrode material demonstrated a substantial surface area (54.32 m2 g-1) measured by Brunner–Emmett–Teller analysis, while scanning electron microscopy results showed that BaMnO3 dispersed tightly on rGO. The fabricated electrode material demonstrated a specific capacitance of 1359.85 F g−1, energy density of 78.62 Wh kg-1 and power density of 322.6 W kg-1 at 1 A g-1 current density. Furthermore, the Nyquist plot revealed a low value of Rct (0.04 Ω), indicating good electrical conductivity, while the material displayed stability even after 5000th cycle. This work revealed that, such extraordinary and outstanding qualities of BaMnO3/rGO nanocomposite provide a viable option for use in next-generation supercapacitor applications along with high stability and cost effectiveness.

Polyaniline/TiO2 nanocomposite for high performance supercapacitor

A binary polyaniline/TiO2 and varied weight ratio TiO2/PANI nanocomposite was successfully fabricated as an electrode for energy storage application. The TiO2 nanoparticles were synthesized via manual irradiation system with wavelength 256 nm and power 125 W. Polyaniline/TiO2 was then prepared by in situ polymerizing TiO2 onto aniline monomer. Polyaniline nanofibers are loaded with TiO2 to product core-shell system. The polyaniline/TiO2 nanocomposite were characterized using XRD, XPS, TEM, TGA, CP and LCR measurements. The structure properties were examined by XRD and XPS, which confirmed preparing polyaniline/TiO2 binary nanocomposite. The thermal stability was investigated using TGA and obtained high stability of polyaniline/TiO2 compared with polyaniline, while the electrochemical properties were examined by LCR measurements. The LCR measurements were appeared dielectric constant and dielectric loss for incorporating TiO2 through PANI. Varied weights ratio TiO2 was worked in increasing the stored energy ability of polyaniline. Notably, the electrochemical investigate results appear that the PANI/TiO2 has a high specific capacitance (250 F/g) compared with pure PANI (200 F/g). KEY WORDS: Supercapacitor, UV irradiation, XPS, LCR, nanofibers Bull. Chem. Soc. Ethiop. 2024, 38(4), 1177-1188. DOI: https://dx.doi.org/10.4314/bcse.v38i4.28

A Comparative Study on the Influence of N‐Doped Primary and Secondary Hydrochars on the Electrochemical Performance of Biobased Carbon Electrodes for Energy Storage Application

AbstractThe hydrothermal carbonization (HTC) technique and subsequent pyrolysis were applied. Herein, two different types of biobased feedstocks, sucrose (Suc) and Miscanthus (Mis), were chosen. Urea served as N precursor for the in situ doping. HTC of Suc and Mis with urea leads to N‐doped hydrochars (N‐HCs). Suc and Mis decompose in different, complex degradation pathways, which leads to the emergence of N‐HCs consisting of distinct ratios of N‐containing primary chars (N‐PCs) and secondary chars (N‐SCs). After pyrolysis, maximum N contents of 5.6 wt % and 4.8 wt % of the N‐doped pyrolyzed hydrochar (N‐PHC) electrodes from Suc and Mis, respectively were reached. The role of PC and SC formation on the impact of N‐doping in the context of physicochemical properties of the N‐PHCs was compared with each other. In this study, they were tested with respect to the influence of N‐PCs and N‐SCs on their electrochemical performance in energy storage application. It turned out that the electrical conductivity (EC) and specific capacitances increased. Highest EC value of 129.1 S ⋅ cm−1 was obtained with N‐PHC based on Suc. Simultaneously, enhanced average specific capacitances of 47.0 F ⋅ g−1 at 5 mV ⋅ s−1 and 3.5 F ⋅ g−1 at 100 mV ⋅ s−1 are ascertained with N‐PHCs from Suc and Mis, respectively.

Engineering time-dependent MOF-based nickel boride 2D nanoarchitectures as a positive electrode for energy storage applications

It is of great importance to design rationally combined metal-organic frameworks (MOFs) with multifunctional nano geometries to develop advanced energy storage devices. We devised a simple room-temperature boronization system to produce ultrathin Ni-ZIF/Ni-B nanosheets with plenty of crystalline-amorphous phase barriers. The Ni-ZIF/Ni-B-24 h nanoflakes electrodes exhibited a specific capacitance of 104.2F g−1 with the cyclic stability of 94.5 % using the flaky architecture and inherent properties of the Ni-ZIF/Ni-B-24 h nanoflakes. Furthermore, an asymmetric supercapacitor made of Ni-ZIF/Ni-B-24 h and activated carbon had a high specific capacitance of 370.7F g−1 at 1 A/g, and the energy density of 131.8 W h kg−1 at a power density of 800 W kg−1. Intriguingly, Ni-ZIF/Ni-B-24 h nanoflakes have consistently delivered higher specific capacities because of the adequate electrochemical active sites and an increase in electron transfer rate during redox reactions.

Tailoring the graphene framework by embedding Nb2O5 and silver nanoparticles for electrodes in energy storage applications

In this study, Nb2O5/GNs and Ag/GNs-based nanocomposites were synthesized via a facile single-step hydrothermal approach. Using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, fourier-transform infrared (FTIR) spectroscopy, and UV–vis spectroscopy, the morphology, functional groups, structure, and optical and electrical properties of the as-prepared materials were examined. XPS studies show the predominant signal at 284.8 eV is attributed to the sp2 carbon atoms (C 1) that comprise graphitic areas, indicating that the majority of the C atoms are arranged in a honeycomb lattice. FTIR spectrum confirms bonding, such as CO, CH2, CO, CC, OH, AgO, and NbONb in the nanocomposite. Further, the specific capacitance (Csp) of the Nb2O5/GNs and Ag/GNs was calculated 603 Fg−1 and 810 Fg−1 at different current densities, The Nb2O5/GNs exhibit 109 Wh/kg and 2180 W/kg energy and power density, respectively. However, the Ag/GNs electrode exhibited an energy density of 145.8 Wh/kg and a power density of 3645 W/kg, with cyclic stability retentions of 93.06 % and 97.02 %, respectively. The capacitance retention finished at 1000 cycles. Moreover, the achieved resistance from the I–V characteristics curve shows enhanced electrical conductivity of synthesized nanocomposites. These results suggested that the materials can have bright future in next-generation energy storage devices.

Boosted electrochemical performance of flower-like carbon microspheres derived from polyimides containing hydroxyl groups for supercapacitor electrodes

Herein, the flower-like microspheres derived from polyimides containing hydroxyl groups are firstly synthesized through a solvothermal technique. Then, the corresponding flower-like carbon microspheres are obtained after high-temperature carbonization. The influences of the poly(amic acid) concentration, solvothermal temperature, and treatment time on the electrochemical behaviors of carbon microspheres are investigated. The optimized carbon sample PC-2-180-10 demonstrates a distinct micro/mesopore characteristic, leading to a specific capacitance of 254.4 F g−1 at 0.5 A g−1. Subsequently, the sample is chemically activated with HNO3 for improving its electrochemical performance. When the HNO3 concentration is optimized as 6 M, the treatment temperature and time are 75 °C and 30 h respectively, the activated carbon microspheres APC-6-75-30 exhibit a maximum specific capacitance of 387.6 F g−1. Moreover, the APC-6-75-30 is symmetrically fabricated into a button-type supercapacitor (SC) device, and the SC shows a specific capacitance of 88.5 F g−1, with an energy density of 11.81 Wh kg−1 at a power density of 240.1 W kg−1. Six months later, the SC still demonstrates a better capacitive performance. Optimizing the solvothermal parameters and HNO3 treatment conditions, this work presents an effective strategy for boosting the electrochemical performance of flower-like carbon microspheres as a promising electrode for energy storage applications.

In-situ electronic modulation of ultra-high-capacity S-modified Cu/Cu2O electrodes for energy storage applications

Due to the modification of anions, an electron redistribution occurs at the metal ions can affect the electronic structure, and induce excellent specific capacity. Herein, we report an effective and low time-consuming method by in-situ wet chemical reduction at room temperature to construct S-modified Cu/Cu2O negative electrode material. Moreover, the sulfur can occupy partial O sites in Cu2O to play a crucial role in the electronic structure of the material, demonstrated by DFT calculation, XRD, XPS and XAS measurements. The prepared S-Cu/Cu2O samples exhibit excellent electrochemical performance with high specific capacity of 669 mAh·g−1 at 1 A·g−1, even 450 mAh·g−1 at 10 A·g−1. When the materials are composed as pseudo capacity-type cathode//battery-like anode (MnO2//S-Cu/Cu2O), and (+) battery-type//battery-type (-) (Ni-Cu hydroxide/Cu(OH)2/CF//S-Cu/Cu2O) hybrid capacitors, they show the energy density of 47.7 and 147.3 Wh·kg−1 at the power density of 636.2 and 800 kW·kg−1, respectively. Otherwise, the flexible MnO2//S-Cu/Cu2O hybrid capacitor is assembled, which also exhibits good performance at different bending conditions. This work can provide a simple method to prepare the electrode materials via in situ anion modification for high-energy density battery-like energy storage systems.

Hydrothermally synthesized MnCo2O4 nanoparticles for advanced energy storage applications

We observed the impact of reaction time on the electrochemical performance of MnCo2O4 nanoparticles, specifically focusing on the overgrowth of nanoparticles over the nanostructure. We characterized the synthesized nanomaterial using XRD, SEM, and XPS techniques to analyze its crystal structure, surface microstructure, and chemical states, respectively. The electrode prepared via a 5-hour hydrothermal reaction exhibited an outstanding areal capacitance of 144 mF/cm2 at a current density of 1A/g. Furthermore, it demonstrated an areal energy density of 4.1 μWh/cm2 at a power density of 0.225 mW/cm2. We assembled an asymmetric supercapacitor (ASC) configuration, MCO-5 h//AC, using MCO-5 h and activated carbon (AC), which showcased exceptional areal capacitance, areal energy density, and power density. These characteristics make it highly suitable for practical applications in energy storage. Overall, our findings highlight MCO-5 h as a promising electrode for energy storage applications.

Candle soot carbon-Co3O4 nanofibers composite as a binder-free electrode for high-performance supercapacitor application: An experimental and theoretical investigation

Extensive research has been conducted on nanostructured metal oxide electrodes for energy storage applications, particularly in supercapacitors, owing to their high specific capacitance. However, a major hindrance to their commercialization is their limited life cycles. To address this issue, incorporating carbon allotropes as a conductive support to enhance the electrode's stability has been explored. In the current work, a novel composite material was synthesized by combining candle soot carbon with cobalt oxide (Co3O4) to create a highly efficient electrode. The optimal composite, with a 2 wt% of candle soot carbon to Co3O4, exhibited utmost specific capacitance (997.5 Fg−1) at 1 Ag−1. After subjecting both electrodes to 10,000 cycles of repetitive charge and discharge, the composite demonstrated a capacitance retention of 83.3 %, while the Co3O4 electrode only achieved 75 % under identical conditions. Additionally, Density Functional Theory (DFT) investigations were performed to elucidate the improved charge-storing capacities of the composite electrode. The computed density of states indicates enrichment of energy states near the Fermi level in the composite when seen to pristine Co3O4. The Partial Density of States (PDOS) analysis illustrates the transportation of charge from the carbon p orbital (candle soot carbon) to the Co d orbital (Co3O4), validating the conductivity improvement in the hybrid configuration, which benefits from enhanced charge storage performance. Overall, the composite material is promising for hybrid supercapacitors, especially due to the incorporation of candle soot carbon as one of its components. It not only enhances the performance of the supercapacitor but also offers the advantage of being a renewable material derived from waste materials. This combination makes the composite an appealing and sustainable choice for next-generation energy storage devices.

Facile synthesis of morphology-controlled hybrid structure of ZnCo2O4 nanosheets and nanowires for high-performance asymmetric supercapacitors.

Controllable synthesis of electrode materials with desirable morphology and size is of significant importance and challenging for high-performance supercapacitors. Herein, we propose an efficient hydrothermal approach to controllable synthesis of hierarchical porous three-dimensional (3D) ZnCo2O4 composite films directly on Ni foam substrates. The composite films consisted of two-dimensional (2D) nanosheets array anchored with one-dimensional (1D) nanowires. The morphologies of ZnCo2O4 arrays can be easily controlled by adjusting the concentration of NH4F. The effect of NH4F in the formation of these 3D hierarchical porous ZnCo2O4 nanosheets@nanowires films is systematically investigated based on the NH4F-independent experiments. This unique 3D hierarchical structure can help enlarge the electroactive surface area, accelerate the ion and electron transfer, and accommodate structural strain. The as-prepared hierarchical porous ZnCo2O4 nanosheets@nanowires films exhibited inspiring electrochemical performance with high specific capacitance of 1289.6 and 743.2 F g-1 at the current density of 1 and 30 A g-1, respectively, and a remarkable long cycle stability with 86.8% capacity retention after 10 000 cycles at the current density of 1 A g-1. Furthermore, the assembled asymmetric supercapacitor using the as-prepared ZnCo2O4 nanosheets@nanowires films as the positive electrode and active carbon as negative electrode delivered a high energy density of 39.7 W h kg-1 at a power density of 400 W kg-1. Our results show that these unique hierarchical porous 3D ZnCo2O4 nanosheets@nanowires films are promising candidates as high-performance electrodes for energy storage applications.

Understanding the Role of the Binder on the Microstructure and Properties of PTFE-Based Solvent-Free Electrodes

Solvent-free processing, also known as dry-processing refers to a group of manufacturing methods which avoid the use of solvents in the production of electrodes for energy storage applications. This concept has been around for more than a decade, although its popularity has increased dramatically over the last couple of years after the purchase of Maxwell technologies by Tesla. Maxwell patented a novel processing route which involves dry mixing the active material powder with a PTFE binder to form an electrode without the use of any solvent. Solvent-free processes have significant advantages in terms of sustainability, safety and cost over conventional slurry casting.A detailed analysis of the slurry casting process showed that around a quarter of the total manufacturing cost of the battery pack originated from solvent associated steps. Avoiding the use of toxic and flammable solvents such as N-methyl Pyrrolidone (NMP) also naturally leads to an improvement in the safety of the manufacturing environment. More importantly, it was reported that the manufacturing steps associated with solvent removal accounted for half of the embodied energy of a typical Li-ion battery. The embodied energy of a Li-ion battery is a crucial figure of merit in terms of sustainability which is too often neglected. To put things into perspective, Volvo has recently published a carbon footprint report for their fully electric Volvo C40 Recharge and compared it to their internal combustion engine (ICE) equivalent, the XC40. They reported that the production of the electric version generated 26 tonnes of CO2-equivalents compared to 16 tonnes for the ICE model, representing a large increase of almost 70% in the embodied energy of the car. Novel and more sustainable manufacturing processes are urgently needed to reduce as much as possible the embodied energy of Li-ion batteries and make them more sustainable to enable a durable green energy transition.Although the concept of solvent-free processing seems attractive, most of its current development is happening behind closed doors in industry. However, an in-depth characterisation of this new type of electrodes and a comparison with conventional slurry cast electrodes would be beneficial to understand the challenges and opportunities brought by these new systems and help accelerate their development on a larger scale. Within the family of solvent-free processes, three main techniques have emerged: dry painting, powder injection molding and PTFE-fibrillation. Studies dedicated to electrodes based on PTFE-fibrillation are rare and often focused on solid-state systems. In order to dispel some of the mystery surrounding the novel microstructures obtained through the PTFE-fibrillation process and their performance, this work focuses on the characterisation of these new electrodes and investigate the role of the PTFE binder on the microstructure and electrochemical performance of solvent-free electrodes. Our results highlight the crucial importance of the PTFE binder on the mechanical properties of the solvent-free electrodes and reveal how the peculiar mechanical behavior of these composite electrodes during the manufacturing process influences the final microstructure of the electrodes and their electrochemical performance. This work presents a deep insight into PTFE-based solvent-free electrodes by investigating their microstructure, mechanical and electrochemical properties using advanced characterization techniques including High Resolution Analytical Scanning Electron Microscopy, X-Ray Computed Tomography, Electrochemical Impedance Spectroscopy and mechanical testing.

Solvent-Assisted Morphology-Induced Nickel Metal–Organic Framework as a Highly Efficient Electrode for Energy Storage Application

Solvent-Assisted Morphology-Induced Nickel Metal–Organic Framework as a Highly Efficient Electrode for Energy Storage Application

Elucidating the Role of Copper-Induced Mixed Phases on the Electrochemical Performance of Mn-Based Thin-Film Electrodes.

Manganese oxide is a fascinating material for use as a thin-film electrode in supercapacitors. Herein, the consequences of copper incorporation on spray pyrolyzed manganese oxide thin films and their electrochemical performance were investigated. The Cu-incorporated manganese oxide thin films were deposited by spray pyrolysis, and their structural and electrochemical properties were thoroughly evaluated. The formation of the spinel Mn3O4 phase with effective Cu incorporation was confirmed by X-ray diffraction investigation. Through Raman studies, it was noticed that mixed phases of manganese oxide tend to form after Cu incorporation, and this result was also reflected in X-ray photoelectron spectroscopic studies. The surface morphology and roughness were also altered by the addition of copper. However, electrochemical measurements implied a reduction in the specific capacitance upon copper inclusion. The cyclic voltammetry test indicated a specific capacitance of 132 F/g for Mn3O4 electrodes, but a substantial drop for copper-incorporated samples due to the mixed manganese phase. The decremental tendency was further supported by galvanostatic charge-discharge studies and electrochemical impedance spectroscopic measurements. These results provide valuable insights into the effects of copper addition in manganese oxide thin-film-based electrodes for energy storage applications.

A novel double perovskite Dy2CoMnO6 as supercapacitor electrode with efficient electrochemical performance

Novel double perovskite oxide Dy2CoMnO6 (DCMO) based electrodes were fabricated for supercapacitor application. Structural studies indicate a monoclinic structure (space group: P21/n). The evidence of structural distortion is observed due to the large extent of decentralization of oxygen electron clouds around Co and Mn atoms in YZ and XZ directions. Micron-sized particles of DCMO constitutes a flat surface of electrodes for faster electrochemical reaction. Room temperature electrochemical performance was investigated using three electrodes set up. Cyclic voltammograms (CV) and Galvanostatic charging–discharging (GCD) curves display significant specific capacitance with super cyclic stability as electrodes. The DCMO electrode shows 87 % cyclic stability over 10,000 cycles. This work produces efficient and stable double perovskite oxide DCMO as electrodes for energy storage applications.

Binder-free hydrothermal approach to fabricate high-performance zinc phosphate electrode for energy storage applications

Metal phosphates are an emerging class of materials with large porosity that endows them with high specific capacity and ionic conductivity. However, the binder and carbon additive are required to fabricate the electrodes which adds extra expenditure to the supercapacitor's overall fabrication cost. The binder-free electrode fabrication provides a hope to eliminate the need for binders and hence the carbon additive for supercapacitor applications. In this work, a binder-free zinc phosphate hydrate (ZPOH) based electrode is fabricated using a cost-effective hydrothermal method. Two additional electrodes were also fabricated – one without carbon additive (ZPOWCB) and another with the addition of carbon additive (ZPOCB) using the conventional slurry preparation method. ZPOH electrode showed remarkable enhancement in the specific capacity compared to the other two electrodes as it achieved a specific capacity of 433 C/g at a current density of 2 A/g. Moreover, ZPOH also showed negligible charge transfer resistance (Rct), depicting good electrolyte ions interaction with the active material. Hence, the easy and simple binder-free hydrothermal approach is more suitable for preparing electrode materials for energy storage applications.

Hierarchical polyaniline/copper cobalt ferrite nanocomposites for high performance supercapacitor electrode

Increasing energy demand needs efficient energy storage devices, especially for mobile applications and wearable electronics. Conducting polymer based nanocomposite offers excellent charge transfer mechanism with high energy storage ability. Herein, we report preparation of polyaniline/copper cobalt ferrite (PANI/CCF) based nanocomposites to fabricate supercapacitor electrodes. In-situ polymerization of PANI ensures the formation of a well-mixed nanocomposite of PANI and CCF. Detailed structural and morphological analysis reveal the formation of a core-shell type structure with CCF as the core and PANI as the shell. The core-shell structure was formed due to the presence of a synergistic interaction between PANI and CCF. Particle size distribution shows a well distribution with an average size ~100–120 nm, contributing significantly towards high energy density at high power density. The supercapacitor electrode based on 8:1 material shows significantly high capacitance of 408.8 F g−1 at a scan rate of 5 mV s−1 and 460.1 F g−1 at 0.5 A g−1 current density. The energy storage capacity enhanced significantly for 8:1 weight ratio of PANI and CCF. The PANI/CCF 8:1 nanocomposite shows energy density of 23 and 18.2 W h kg−1 at power density of 150 and 1500 W kg−1, respectively with a good cyclic life (~91 % retention after the 1500 cycle). Consequently, PANI/CCF 8:1 nanocomposite has excellent potential for supercapacitor electrodes for energy storage applications.

Graphite Paper-based Device for Energy Storage Application

The demand for versatile flexible energy storage device has arisen due to their potential, application in wearable and portable electronic product. This study presents the characterization of graphite paper-based capacitor and supercapacitor that are produced utilising commercially available pencils to draw a design by developing cheap, green, and reliable low profile electrical electrodes. The objectives of this study are to design graphite paper-based electrodes for energy storage application, characterize the physical properties of the electrodes and electrical properties of the device. Material characterization have been performed including morphology analysis of the electrodes using field emission scanning electron microscope (FESEM), compositional structures by using Energy dispersive X-ray spectroscopy (EDX) and chemical properties of the graphitic electrodes using Raman spectroscopy. Next, the electrical performance of the pencil drawn capacitor and supercapacitor have been performed. It is found that the Acidic G/PANI-Paper supercapacitor sample shows the best electrical performance in terms of lowest resistance with 0.59 MΩ, 1.12 MΩ, 1.8 MΩ and highest capacitance with 27.5 μF, 38.1 μF, 55.25 μF for respective 6 cm2, 8 cm2 and 10 cm2 area size. These characteristics show that the graphite-paper based device has a great potential in flexible energy storage applications.

Laser-induced transient conversion of rhodochrosite/polyimide into multifunctional MnO2/graphene electrodes for energy storage applications

Laser-induced graphene (LIG) has been extensively investigated for electrochemical energy storage due to its easy synthesis and highly conductive nature. However, the limited charge accumulation in LIG usually leads to significantly low energy densities. In this work, we report a novel strategy to directly transform natural rhodochrosite into ultrafine manganese dioxide (MnO2) nanoparticles (NPs) in the polyimide (PI) substrate for high-performance micro-supercapacitors (MSCs) and lithium-ion batteries (LIBs) through a scalable and cost-effective laser processing method. Specifically, laser treatment on rhodochrosite/polyimide precursors induces the thermal explosion, which splits rhodochrosite (10 μm) into MnO2 NPs (12–16 nm) on the carbon matrix of LIG due to the sputtering effect. Benefiting from largely exposed active sites from the ultrafine MnO2 and the synergetic effect from highly conductive LIG, the MnO2/LIG MSCs show a high specific capacitance of 544.0 F g−1 (154.3 mF cm−2; 14.16 F cm−3) at 3 A/g and 82.1% capacitance retention after 10,000 cycles at 5A/g, in contrast to pure LIG (<100 F g−1). Moreover, the MnO2/LIG-based LIBs show the highest reversible discharge capacity of ∼1097 mAh g−1 at 0.2 A/g and ∼ 866.4 mAh g−1 at 1.0 A/g. This study opens a new route for synthesizing novel LIG-based composites from natural minerals.