Cyclic Galvanostatic Charge-discharge Research Articles

Designing high-performance asymmetric and hybrid energy devices via merging supercapacitive/pseudopcapacitive and Li-ion battery type electrodes

We report a strategic development of asymmetric (supercapacitive–pseudocapacitive) and hybrid (supercapacitive/pseudocapacitive–battery) energy device architectures as generation–II electrochemical energy systems. We derived performance-potential estimation regarding the specific power, specific energy, and fast charge–discharge cyclic capability. Among the conceived group, pseudocapacitor–battery hybrid device is constructed with a high-rate intrinsic asymmetric pseudocapacitive (α − MnO2/rGO) and a high-capacity Li-ion intercalation battery type (po-nSi/rGO) electrodes. The experimental setup was developed to measure the current sharing between the two different active materials in a single device allowing us to distinguish the contribution of each active electrode material. The combined potentiostatic cyclic voltammograms and galvanostatic charge–discharge cycling profiles provided gravimetric capacity exceeding 600 F/g (or 180.5 mAh g−1 and ≥ 35mC/cm2) resulting in higher specific power and specific energy densities of 6.5 kW kg−1 and 33.5 Wh kg−1 with Coulombic efficiency (CE) and capacitance retention exceeding ≥ 85–90%, reported to date for full cell configuration, compared with symmetric or half-cell configurations (ca. 0.1 kW kg−1 and 13.7 Wh kg−1). Other systems studied provided specific energy ranged between 28 Wh kg−1 and 50 Wh kg−1 and specific power between 6.5 kW kg−1and 1.3 kW kg−1. Moreover, the behavior of such asymmetric hybrid devices represented a linear combination of the two active electrode material systems. The use of aqueous (and organic) electrolytes for asymmetric electrodes dramatically improved device performance and stability depending upon the electrode combination forming hybrid energy devices. We attribute the observed efficient performance of these hybrid devices induced by hybridized and emergent redox chemistries of merged electrode materials and dynamical processes at the electrode-electrolyte interfaces (intrinsic electroactivity, optimized double-layer and quantum capacitance) which play multiple roles. These energy devices are commercially relevant due to their potential viability in future hybrid electric vehicles, smart electric grids, electrocatalytic fuel production, space (micro-satellites), and miniaturized flexible electronic and wearable biomedical devices.

Enhancing the electrochemical efficiency of metal-organic frameworks through integration of chromium nitride interfacial layer for efficient hybrid supercapacitors

Transition metal nitrides are highly stable and electrochemically efficient, making them a promising material for supercapacitor electrodes. Herein, for assessing the synergistic effects of metal-organic framework via transition metal nitrides, we synthesized chromium nitride electrode using magnetron sputtering followed by the deposition of copper-trimesic acid. Electrochemical testing in half and full cell configurations reveals that chromium nitride/copper-trimesic acid has the lowest charge transfer resistance, indicating its quick charge transport pathways, leading to an increased specific capacity (1651C/g at 1.5 A/g) and notable rate capability. Persuaded by the exceptional capacitive and charge storage potential, a two-cell mode-based hybrid supercapacitor was fabricated using activated carbon and chromium nitride/copper-trimesic acid. This combination demonstrated the highest energy density of 94.5 Wh/kg, maximum power density of 7750 W/kg while functioning at 1.6 V with cycling stability of 97.9 % after 3000 galvanostatic charge discharge cycles. Additionally, for examining the diffusive and capacitive behaviors of devices, two different semi-empirical models were further used and compared, which shed light on the special characteristics and implementation of supercapattery device.

Enhancing Supercapacitor Performance of NiCoMn‐Layered Double Hydroxide with Ag–Citrate/Polyaniline Nanocomposites

Layered double hydroxide (LDH) has a layered structure, which makes it a strong candidate for supercapacitors (SC) due to its high surface area. However, they suffer from low conductivity due to insufficient charge transfer across their layers. This research aims to overcome this obstacle by introducing conductive channels among the layers by the addition of Ag–citrate and polyaniline (PANI). Consequently, five electrodes (S1–5) were made from NiCoMn LDH (referred to as LDH henceforth) and 2:1 Ag–citrate and PANI composite (Ag/PANI) in different ratios and made into electrodes. Electrochemical analysis revealed successful improvement in the performance of LDH as the fraction of Ag/PANI increased until it equaled Ag/PANI where the highest specific capacitance of 617 F g−1 was obtained, which is 12% greater than the value for solely LDH electrode (550 F g−1). A device was fabricated with the best electrode (S3) and activated carbon electrode, which demonstrated energy densities and power densities of 41 WhKg−1 and 412.5 W Kg−1 and 14 WhKg−1and 8250 W Kg−1 at 0.5 and 10 A g−1 current densities, respectively. It also exhibited a capacitive retention of about 75% at 3000 galvanostatic charge–discharge cycles. These results encourage the use in of NiCoMn LDH, in a 1:1 ratio with Ag/PANI in SCs due to its remarkable performance.

Investigation of Bi2MoO6/MXene nanostructured composites for photodegradation and advanced energy storage applications

This study presents nanostructured composite Bi2MoO6/MXene heterostructure by using hydrothermal method for photodegradation of the congo-red dye and also for energy storage devices. X-ray diffractometer (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) were performed to examine the structural properties along with surface area and porosity of the material. Due to addition of MXene the larger surface area and improved pore size help to quickly break down additional organic pollutants by adsorbing them. The band gap of Bi2MoO6/MXene nanostructured composite reduced to 2.4 eV suggesting transfer of electrons from VB to CB. Bi2MoO6/MXene exhibits a high (92.3%) photocatalytic degradation rate for a duration of 16 min which was verified using UV-visible spectroscopy, also scavenger test was conducted to ascertain the reactive agent along with the degradation pathway was confirmed by LCMS. Elemental content was also established by using inductively coupled plasma mass spectrometry (ICP-MS). For estimating energy storage capacity cyclic voltammetry (CV) was performed. It was observed Bi2MoO6/MXene nanostructured composite electrodes had specific capacitance of 642.91Fg− 1, power density of 1.24 kWkg− 1, and energy density of 22.32 Whkg− 1 at a current density of 5Ag− 1 also it exhibited 64.42% capacity retention having current density 20 Ag− 1 throughout 10,000 Galvanostatic charge discharge (GCD) cycles. High electrical conductivity of Bi2MoO6/MXene electrode was again examined by Electrochemical impedance spectroscopy (EIS). These findings demonstrate the potential of Bi2MoO6/MXene nanostructured composites in both photodegradation and energy storage applications.

High‐Performance Alkaline Battery‐Supercapacitor Hybrid Based on Bimetallic Phosphide/Phosphate

AbstractTransition metal‐based materials explored for energy storage applications viz. batteries, supercapacitors and more recently battery‐supercapacitor hybrids (BSHs) abundantly involve Co‐based materials. However, the supply chain issues and low electronic conductivity force us to look for alternative options. In this regard, Co‐free binary metal phosphide/phosphate consisting of Ni and V metal (NiVP/Pi) microspheres as the positive electrode of BSH which shows a high specific capacity of 502 C g−1 (1004 F g−1) at 2 mV s−1 while retaining a high specific capacity of 214 C g−1 (428 F g−1) at 12 A g−1 is reported. The high electronic conductivity of binary metal phosphide in NiVP/Pi electrode and the rich electrochemical active sites due to Ni and V metal centres results in exciting performance. More interestingly, the hybrid device is successfully developed by employing NiVP/Pi as the positive electrode and carbon nanotubes (CNTs) as the negative electrode. The hybrid device (NiVP/Pi//CNT) is able to achieve a maximum energy density of 22.17 Wh kg−1 and a power density of 5 kW kg−1 with 91.7% capacitance retention after 7500 continuous galvanostatic charge–discharge cycles.

Y-Shaped Acceptor-π-Donor-π-Acceptor Configured Anthraquinone-Tethered Phenothiazine Molecular Scaffold for High-Performance Organic Pseudocapacitors.

For the first time acceptor-π-donor-π-acceptor (A-π-D-π-A) based Y-type organic electrode material have been designed and successfully utilized in supercapacitor (SC) application. This Y-type molecular architecture coined as AQ-Im-PTZ-Im-AQ based on anthraquinone (AQ) (A)-imidazole (Im) (π)-phenothiazine (PTZ) (D)-imidazole (Im) (π)-anthraquinone (AQ) (A) in combination with graphite foil (GF). As-fabricated PTZ-Im-AQ/GF and AQ-Im-PTZ-Im-AQ/GF electrode have shown the good energy storage properties in three-electrode supercapacitor system. Moreover, two-electrode symmetric supercapacitor (SSC) device based on AQ-Im-PTZ-Im-AQ/GF electrode exhibited specific capacitance (Csp) of 68.97 F g-1 at 1 A g-1 current density. The specific electron density (ED) of SSC was observed to be 12.06 Wh kg-1 at a specific power density (PD) of 1798.50 W kg-1. The SSC device exhibited 81.62 % of Csp retention after 5000 galvanostatic charge-discharge (GCD) cycles. For real world applications, AQ-Im-PTZ-Im-AQ/GF electrode was tested in symmetric Csp coin cell with applied potential voltage window of -0.4 to 1.0 V was found to be 112.32 F g-1 at 0.5 A g-1. Moreover, it realized high specific capacitance and high energy density of 19.66 Wh kg-1 at 891.94 W kg-1 power density. As a results, AQ-Im-PTZ-Im-AQ/GF make as an attractive electrode material for application in next-generation SCs.

Constructing Co3O4 Nanowire@NiCo2O4 Nanosheet Hierarchical Array as Electrode Material for High-Performance Supercapacitor.

The Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array was constructed on Ni foam using hydrothermal and annealing approaches in turn, from which a NiCo2O4 nanosheet could self-assemble on the Co3O4 nanowire. The structure and morphology of the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array were characterized via XRD, EDS, SEM, and FESEM, respectively. The electrochemical performance of the composite array was measured via a cyclic voltammetry curve, galvanostatic current charge-discharge, charge-discharge cycle, and electrochemical impedance and then compared with the Co3O4 nanowire. The results show that the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array could reach a high value of 2034 F g-1 at a current density of 2.5 A g-1. After 5000 galvanostatic charge-discharge cycles, the specific capacitance of the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array could still maintain 94.7% of the original value. Therefore, the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array would be a desirable electrode material for a high-performance supercapacitor.

NiCo-MOFs derived carbon matrix composites: A promising electrode construction for high-performance supercapacitors

Metal-organic frameworks (MOFs) are great precursors and templates for preparing adsorbents, catalysts and electrodes due to the porous structure and high specific surface area. We report a promising approach to prepare nanocrystalline Co, Ni sulfides (CNS) embedded and N self-doped porous carbon (NPC) matrix composites derived from NiCo-MOFs. The CNS@NPC composite was investigated as electrodes for hybrid supercapacitors (HSCs). The prepared electrode achieved specific capacitance of 2789 F g−1 at 1 A/g, and high capacitance retention of 88.93% after 6000 galvanostatic charge–discharge (GCD) cycles under 10 A/g. The HSC structured with CNS@NPC//AC achieved an energy density of 46.79 Wh kg−1 at power density of 800 W kg−1. Meanwhile, specific capacitance of 131.56 F g−1 at 1 A/g and capacitance retention of 99.17% over 6000 GCD cycles under 3 A/g were obtained. Space confinement by the carbon skeleton effectively prevents the aggregation of the redox active nanocrystalline and improves the durability of the electrode. Meanwhile, the carbon skeleton provides abundant charge transfer channels to enhance the redox reaction. In other words, synergistic effect of the carbon skeleton and the active redox nanocrystalline significantly improves the electrochemical properties of the composite.

Pd–Co₃O₄/acetylene black nanocomposite as an efficient and robust bifunctional ORR/OER electrocatalyst for rechargeable zinc-air batteries

Developing cost-effective and high-performing bifunctional electrocatalysts is pivotal for advancing rechargeable zinc-air batteries (ZABs). In this study, a Pd–Co₃O₄ loaded on acetylene black (Pd–Co₃O₄/C) electrocatalyst was developed with excellent properties for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) using reduced H₂PdCl₄ to modify Co₃O₄/C. The experimental findings indicate that the Pd–Co₃O₄/C electrocatalyst exhibits a favorable half-wave potential for ORR at 0.91 V, a feasible potential for OER at 1.48 V (measured at 10 mA/cm2), also minor Tafel slopes for both ORR (44.65 mV/dec) and OER (58.41 mV/dec). Additionally, it evidences a power density of 186 mW/cm2 in ZABs and good durability during galvanostatic charge-discharge cycling. The impressive performance of Pd–Co₃O₄/C can be ascribed primarily to the beneficial synergistic effect resulting from the composition of Co₃O₄ and Pd embedded within graphite carbon. This research lays the groundwork for the expansion of additional cost-effective and highly effective electrocatalysts in the coming years.

Synthesis and performance evaluation of bio-derived and synthetic carbon as lithium-sulfur battery cathode

The next-generation of batteries need be both energy dense and environment friendly. Lithium sulfur batteries (LSBs) satisfy both criteria but their practical implementation is marred by the highly resistive nature of sulfur. Carbon-based cathodes play a vital role in mitigating the issue because their high conductivity allows for effective electron transfer during electrochemical cycling. Synthesis and electrochemical evaluation of carbon-based cathodes from two different sources for LSBs was carried out. Herein, two kinds of carbon, namely bio-derived carbon from coconut shells (CC500) and N-doped carbon (NC) from polyacrylonitrile fibers were synthesized and sulfur was incorporated via the melt diffusion route. The composites are characterized by PXRD and TGA, which determined 80 wt% mass loading of sulfur. The higher intensity of G-band over D-band in Raman spectroscopy indicates greater graphitic character for CC500 compared to NC. SEM images show large macro-pore like tunnels in CC500 while NC appears are irregular chunks. EDAX spectra showed 20 wt% N content in NC while CC500 is largely carbon with some minor surface oxygen. In galvanostatic charge–discharge cycling of coin cells, bare CC500/S shows better specific capacity compared to NC/S samples but the trend flips once a separator modified with 4 mg of graphene oxide (GO) is introduced (indicated as NC/S/GO4 and CC500/S/GO4). This points towards synergy between N-doped carbon and GO layer in retaining the soluble polysulfides in the catholyte region. NC/S/GO4 exhibited better capacity i.e., 1453, 1024, 866, 787, 697 mAh/g versus 1016, 779, 672, 551, 441 mAh/g offered by CC500/S/GO4 when discharged at 50, 100, 200, 300 and 500 mA/g, respectively.

Superior cycle stability and enhanced pseudocapacitive performance of NiAl-LDH decorated carbon cloth for supercapacitor application

Pseudocapacitors, particularly using layered double hydroxides as cathode material, offers high-power capability and increased energy density, making them popular choices for energy storage devices. This study presents a unique porous structure featuring nickel aluminium layered double hydroxide (NiAl-LDH) deposited onto activated carbon cloth (CC) via a single-step electrochemical process. The NiAl-LDH@CC composite demonstrates exceptional pseudocapacitive capabilities with a specific capacitance of 5893.8 mF cm−2 at a current density of 0.7 mA cm−2 calculated from galvanostatic charge–discharge (GCD) responses. An asymmetric supercapacitor (ASC) is constructed using activated carbon cloth (CC) as anode and NiAl-LDH@CC as cathode. The as-built ASC device, with an operational voltage of 1.6 V, achieves a substantial specific capacitance of 310 mF cm−2 at a current density of 0.2 mA cm−2, along with a high energy density ∼51.67 μWh cm−2 and a power density ∼913.84 μW cm−2. An outstanding cycle stability is also observed with a retention rate of 90 % after 10000 continuous GCD cycles.

Charge storage mechanism and pseudocapacitance performance of NiO and Ce-doped NiO synthesized via modified combustion technique

Supercapacitors, as promising energy storage devices, have gained significant attention due to their ability to deliver high power and efficient charge storage mechanisms. In this work, we report the synthesis and electrochemical characterization of pristine NiO and Ni1-xCexO (x = 0.01, 0.02, 0.03) nanoparticles using a single-step auto ignition combustion method. Preliminary investigations indicate that Ni1-xCexO (x = 0.02) nanoparticles (2 % Ce doping) exhibit superior specific capacitance compared to other compositions. Therefore, we focused on structural, morphological, and vibrational studies on pristine and 2 % Ce-doped NiO. XPS and BET techniques were explored to assess the electronic state and porosity of the samples. Subsequent electrochemical performance evaluations included Cyclic Voltammetry (CV) at various scan rates, Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopic (EIS) techniques. From CV at a scan rate of 5 mVs−1, specific capacitance values of 419 Fg-1 and 604 Fg-1 were obtained for pristine and 2 % Ce-doped NiO, respectively. GCD studies revealed a specific capacitance of 381 Fg-1 for 2 % Ce-doped NiO at a current density of 1 Ag-1 and demonstrated capacitance retention of 95.1 % over 3000 GCD cycles for a current density of 4 Ag-1. The symmetric two-electrode supercapacitor cell demonstrates exceptional electrochemical performance, exhibiting a high specific capacitance of 122 Fg-1, an impressive energy density of 8.17 WhKg−1, a power density of 700 WKg-1 at 1 Ag-1, and a remarkable 88 % capacitance retention after 5000 GCD cycles. DFT calculations suggest that Ce doping significantly alters pristine NiO's electronic and structural features due to lattice strain. Our work highlights the enhanced electrochemical performance of 2 % Ce-doped NiO and its potential as a good-quality supercapacitor material.

Reversible storage of tetraethyl ammonium cation in CFx-based cathode

Carbon fluorides (CFx) are considered as the potential cation storage materials in alkali metal-based battery systems because of the high theoretical specific capacity (865 mAh g-1 when x = 1). However, the reversibility of cathode reaction is seriously disturbed by the strong metal-fluorine interactions among the electrode products (e.g., LiF). By contrast, the relatively weak N-F bond makes the CFx-based battery system using quaternary ammonium cation (QAA+) a promising alternate, but the electrode mechanism between CFx and QAA+is little understood yet. In this work, tetraethylammonium cation (TEA+) is employed as the charge carrier using the electrolyte solution of sulfolane (SL) for CFx cathode. The CF0.56 electrode exports 710 mAh g-1 during the initial TEA+-CF reaction, and the electrode product (TEAF) can be decomposed under elevated potential that yields amorphous carbon fluoride and a reversible capacity of ∼300 mAh g-1 can be reached in the subsequent galvanostatic charge-discharge cycles. The TEAF product is non-crystallizable that exists in a sticky form on the surface of electrode, which contributes to an improved electrode structural stability while also leads to an unsatisfactory performance of the amorphous carbon fluoride with large number of superficial active sites. The electrode mechanism and the mechanical property of electrode interface are discussed in depth by in-situ Raman and electrochemical quartz crystal microbalance (EQCM) methods.

Waste Bakelite Board Derived Activated Carbon for Supercapacitor Electrode

The low biodegradability of Bakelite waste raises concerns for the environment as it is typically dumped in landfills. Herein we present regenerated activated carbon (AC) prepared from waste Bakelite board. Preparation of the ACs involves carbonization and KOH activation. Afterwards, the as-made AC were doped with N urea and subsequently pyrolyzed at high temperature. The resulting AC, with and without N-doping have been evaluated in supercapacitor. We demonstrate an N-doped AC that exhibits a specific capacitance (Csp) as high as 203.0 F g−1 at 0.5 A g−1 and retains 93.1% of the Csp after 5000 galvanostatic charge discharge (GCD) cycles at 3 A g−1. We also show that a symmetric supercapacitor exhibits a maximum energy density of 10.3 Wh kg−1 at 250 W kg−1. In general, our work shows a cost-effective approach towards high-performance waste-regenerated ACs.

Wide electrochemical stability window of NaClO4 water-in-salt electrolyte elevates the supercapacitive performance of poly(3,4-ethylenedioxythiophene)

Water-in-salt electrolytes (WiSEs) have emerged as the primary preference in the domain of aqueous-based supercapacitors, thanks to their wide electrochemical stability window (ESW > 1.23 V). Here, we have chemically synthesized a unique lettuce coral-like structure of tosylate doped-poly(3,4-ethylenedioxythiophene) (PEDOT-tos) and tested it for supercapacitor application in a 17 molal (m) NaClO4 WiSE, achieving an ESW of 1.9 V. The energy and power densities (Ed and Pd) of our PEDOT-tos supercapacitor are as high as 14 Wh kg-1 and 7210 W kg-1, respectively, with over 80 % capacitance retention after 10,000 continuous Galvanostatic charge-discharge cycles. The NaClO4 WiSE increases the Ed and Pd of PEDOT by several folds compared to traditional H2SO4 electrolyte. This work encourages the exploration of a suitable combination of a PEDOT-based composite material and WiSE for high-performance supercapacitors.

Ligand-engineered Fe(II)-metallo-supramolecular polymer with benzothiadiazole: Boosting electrochromic energy storage efficiency

The development of intelligent electrochromic energy storage devices that visually display color changes to indicate their charging and discharging status while offering high energy and power densities is gaining interest as a renewable energy solution. Our research engineered a bisterpyridine ligand (BTZ) with a benzothiadiazole spacer and its metallo-supramolecular polymer (Fe-BTZ) via Suzuki coupling and complexation reactions. Spectroscopic, morphological, and structural characterizations revealed nano-rod morphology due to higher aggregation of 1D Fe-BTZ metallo-supramolecular polymer. Quasi-solid-state electrochromic devices with Fe-BTZ as the active layer exhibited significant color changes (matte purple to dirty yellow), an optical contrast of 65.2 % at 567 nm, high coloration efficiency (518.2 cm2/C), quick coloration (0.5 s) and bleaching (1.8 s), and exceptional electrochromic durability compared with commonly used Poly-Fe metallo-supramolecular polymer. Conjugated ridged benzothiadiazole spacers enhanced electron mobility between the Fe-center during electrochemical transitions, increasing coloration efficiency, durability, and electrochromic speed. The Fe-BTZ and Prussian blue (PB)-based quasi-solid-state energy storage device also showed fast response times (1.1 s and 1.9 s), high CE (1077 cm2/C), 6500-cycle durability, high volumetric capacitance (70.1 ± 4 F/cm3) with a specific capacity of 10.96 mAh/g at 0.14 A/g current density and 74 % capacitance retention over 20,000 galvanostatic charge–discharge cycles. The device’s ability to power 18 red LEDs demonstrates its practical applicability.

Probing the performance of Co-precipitated Co3(PO4)2@W3(PO4)4/GO electrodes for supercapacitor application

A critical first step in realizing high-performance supercapacitors is the growth of functional electrodes that are inexpensive, stable, and extremely active. To create a variety of electrodes, we present here an inventive approach to fabricating an ordered microporous Co3(PO4)2@W3(PO4)4/GO composites electrode on a nickel foam (NF) substrate that was first created via co-precipitation techniques for nanoparticles and then drop casting method for fabrication of these electrodes. The Co3(PO4)2@W3(PO4)4/GO composite electrodes show good electrochemical activity in three electrode configurations, thanks to its abundant active sites, and high specific surface area provided by graphene oxide (GO) structured microporous structure that facilitates the charge/mass transfer processes. Additionally, Co3(PO4)2@W3(PO4)4/GO composite electrodes are rightly employed as binder-free electrodes for supercapacitor applications, providing excellent specific capacitances, energy and power densities as well as good electrochemical firmness. The Co3(PO4)2@W3(PO4)4/GO electrode exhibits excellent performance, delivering a high specific capacitance of 1230 F/g from cyclic voltammetry (CV), 1420 F/g from galvanostatic charge-discharge (GCD) and long-term cycling stability of over 74.7 % after 10, 000 complete cycles.

Nitrogen-doped graphene quantum dot embedded polyaniline for the fabrication of high-performance flexible supercapacitor with enhanced cycling stability

This article explains the synthesis of high surface area nitrogen-doped graphene quantum dots embedded polyaniline (PANI) and its effectiveness in fabricating flexible printed supercapacitors. A noticeable change in polyaniline's morphology and specific surface area suggests the successful incorporation of graphene quantum dots into the polymer matrix. The synergistic interaction of polyaniline with graphene quantum dots is evident in its energy storage performance. The fabricated supercapacitor prototype with PVA/HCl gel electrolyte exhibited a very high areal capacitance of 128.01 mF cm−2, with an areal energy density of 11.40 μWh cm−2, and a power density of 640 μW cm−2 at 1.6 mA cm−2 current density. Most importantly, the developed supercapacitor exhibited 76.70% of original capacitance after 5000 galvanostatic charge-discharge cycles, which was found to be far better result than a supercapacitor fabricated with pristine polyaniline. Furthermore, the developed supercapacitor demonstrated excellent mechanical stability, retaining its performance at diverse angles and even after 4000 bending cycles. These characteristics make PANI/N-GQD-based supercapacitors appropriate for wearable devices requiring flexibility, cycling stability, and mechanical toughness.

Improving Lithium-Ion Battery Performance: Nano Al2O3 Coatings on High-Mass Loading LiFePO4 Cathodes via Atomic Layer Deposition

Lithium iron phosphate (LiFePO4 or LFP) is a promising cathode material for lithium-ion batteries (LIBs), but side reactions between the electrolyte and the LFP electrode can degrade battery performance. This study introduces an innovative coating strategy, using atomic layer deposition (ALD) to apply a thin (5 nm and 10 nm) Al2O3 layer onto high-mass loading LFP electrodes. Galvanostatic charge–discharge cycling and electrochemical impedance spectroscopy (EIS) were used to assess the electrochemical performance of coated and uncoated LFP electrodes. The results show that Al2O3 coatings enhance the cycling performance at room temperature (RT) and 40 °C by suppressing side reactions and stabilizing the cathode–electrolyte interface (CEI). The coated LFP retained 67% of its capacity after 100 cycles at 1C and RT, compared to 57% for the uncoated sample. Post-mortem analyses, including scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), were conducted to investigate the mechanisms behind the improved performance. These analyses reveal that Al2O3 coatings are highly effective in reducing LFP electrode degradation during cycling, demonstrating the potential of ALD Al2O3 coatings to enhance the durability and performance of LFP electrodes in LIBs.

Incorporating Ag into Nd-Succinate MOF: Tunned electrochemical supercapacitor behaviour of Ag modified Nd-Succinate and electrochemical reaction mechanism

The electrode materials must be tailored to achieve higher energy and power densities and thus improve the supercapacitor's performance. This study explores the impact of incorporating Silver (Ag) into a Neodymium-Succinate Metal Organic Framework (Nd-Succinate) on supercapacitor behaviour. Initially, the Nd-Succinate MOF was characterized by structural, morphological, and spectroscopic characterizations. Subsequently, Ag/Nd-Succinate was synthesized and characterized. The electrochemical performance of Ag/Nd-Succinate was evaluated in a 6 M KOH electrolyte; the results indicated a significant enhancement in supercapacitor performance upon incorporating Ag into parent Nd-Succinate. From galvanostatic Charge-Discharge cycles (GCD), the capacitance for Ag/Nd-Succinate was determined to be 1389 F/g, i.e., 42 % higher than that of bare Nd-Succinate which was measured at 978 F/g. at a current density of 1.25 A/g. Ag/Nd-Succinate showcased an 89 % retention value for multiple retention cycles, slightly higher than the retention value obtained (84 %) for Nd-Succinate. The results of electrochemical experiments (Cyclic voltammetry (CV) and Electrochemical Impedance Spectra (EIS)) provided information about the nature of electron transfer and capacitance enhancement upon the introduction of Ag into Nd-Succinate. These findings provide valuable information on modifying MOFs and introducing metal that will help produce high-performance supercapacitor electrodes.