High Electrochemical Performance Research Articles

High voltage electrochemical performance of ultrahigh-Ni cathode via in situ constructed nano-LiF and CNT composite cathode electrolyte interphase layer

Ultrahigh-nickel LiNixCoyMn1-x-yO2 cathode material (Ni content ≥ 0.9) is of great significance for the development of high energy density of lithium-ion batteries. However, its high surface activity leads to more surface residual lithium formation and deterioration of electrochemical performance, especially at high voltage. Here we add NH4F and nitrogen-doped carbon nanotubes (CNT) during the dimethyl carbonate (DMC) washing process, and constructed in situ the nano-LiF and CNT composite cathode electrolyte interphase (CEI) layer while removing part of residual lithium, effectively optimizing the surface environment of LiNi0.9Co0.05Mn0.05O2. The modified LiNi0.9Co0.05Mn0.05O2 has a capacity retention rate of 61.3 % after 200 cycles between 2.8 and 4.5 V at 1C, significantly higher than the 46.7 % of the unwashed sample, and a specific discharge capacity of 146.9 mAh g−1 at 5C, compared to 127.5 mAh g−1 for the unwashed sample. Benefit from the alleviation of polarization and the increase of Li+ diffusion coefficient, the stable CEI layer provides effective protection for LiNi0.9Co0.05Mn0.05O2 under 4.5 V, alleviating surface side reactions. In this paper, a simple and effective strategy is developed to optimize the surface of Ni-rich cathode material, which provides a new insight for the treatment of surface residual lithium.

MOF-Derived Zn/N-Doped Porous Carbon Film on a Carbon Nanotube for High-Performance Supercapacitors.

Designing high-performance binder-free electrochemical electrodes is crucially important toward supercapacitors. In this paper, a Zn/N-doped porous carbon film coating on flexible carbon nanotubes (ZIF-8@CT-800) derived from the epitaxial Zn-MOF film growth on cotton textile was successfully fabricated via a combination of the liquid-phase epitaxial (LPE) method and calcination treatments. The ZIF-8@CT-800 serves directly as a self-supported electrode for supercapacitors and exhibits a high areal capacitance of 930 mF·cm-2 at a current density of 1 mA·cm-2 and a good recyclability of 86% after 2000 cycles. The excellent supercapacitor property is ascribed to the unique structural design of ZIF-8@CT-800, which provides appropriate channels for enhanced electronic and ionic transport as well as increased surface area for accessing more electrolyte ions. This work will provide significant guidance for designing MOF-derived porous carbon to construct flexible binder-free electrode materials with high electrochemical performance.

Influence of A-Site Deficiency and Ca Concentration on the Electrical and Crystallographic Properties of (Nd0.2Sr0.7-x Ca x ) y Ti0.95Fe0.05O3-δ-Based Fuel Electrode for Solid Oxide Cells.

This study explores the impact of A-site deficiency and Sr/Ca ratio on the electrochemical and crystallographic properties of a (Nd0.2Sr0.7-x Ca x ) y Ti0.95Fe0.05O3-δ hydrogen electrode for solid oxide cells under reducing and air atmospheres. 5% and 10% A-site deficient (Nd0.2Sr0.7-x Ca x ) y Ti0.95Fe0.05O3-δ (x = 0.35-0.45, y = 1.05, 1) (referred to as 5NSCTF-x and 10NSCTF-x) materials were studied, while the ratio between A-site cations was kept the same with both deficiencies. The results demonstrate that the extent of A-site deficiency and the Ca concentration in the A-site have a significant impact on the microstructure (sinterability), conductivity, and catalytic activity of electrodes. Segregation of Nd from the lattice with 5% A-site deficiency was observed as a result of thermal treatment at low pO2. Among the studied materials, the highest total electrical conductivity of porous electrode layer at 850 °C and in 97% H2 + 3% H2O atmosphere was 4.8 S cm-1 observed for the Nd0.2Sr0.35Ca0.35Ti0.95Fe0.05O3-δ (10NSCTF-35). The highest electrochemical performance was observed in the case of Nd0.2Sr0.25Ca0.45Ti0.95Fe0.05O3-δ (10NSCTF-45), which showed a polarization resistance value equal to 0.19 Ω cm2 after 100 h of stabilization at 800 °C in a humidified (1.7% H2O) H2 atmosphere. The best electrochemical performance with 606 mW cm-2 power density at 850 °C in 98.3% H2 + 1.7% H2O atmosphere was demonstrated by a 50 wt % Nd0.2Sr0.25Ca0.45Ti0.95Fe0.05O3-δ + 50 wt % Ce0.9Gd0.1O2-δ composite.

Modulating Surface Architecture and Electronic Conductivity of Li-rich Manganese-Based Cathode.

Li-rich manganese-based cathode (LRMC) has attracted intense attention to developing advanced lithium-ion batteries with high energy density. However, LRMC is still plagued by poor cyclic stability, undesired rate capacity, and irreversible oxygen release. To address these issues, herein, a feasible polyvinylidene fluoride (PVDF)-assisted interface modification strategy is proposed for modulating the surface architecture and electronic conductivity of LRMC by intruding the F-doped carbon coating, spinel structure, and oxygen vacancy on the LRMC, which can greatly enhance the cyclic stability and rate capacity, and restrain the oxygen release for LRMC. As a result, the modified material delivers satisfactory cyclic performance with a capacity retention of 90.22% after 200 cycles at 1C, an enhanced rate capacity of 153.58mAhg-1 at 5C and 126.32mAhg-1 at 10C, and an elevated initial Coulombic efficiency of 85.63%. Moreover, the thermal stability, electronic conductivity, and structure stability of LRMC are also significantly improved by the PVDF-assisted interface modification strategy. Therefore, the strategy of simultaneously modulating the surface architecture and the electronic conductivity of LRMC provides a valuable idea to improve the comprehensive electrochemical performance of LRMC, which offers a promising reference for designing LRMC with high electrochemical performance.

Facile construction of porous carbon fibers from coal pitch for Li-S batteries

Coal pitch, an important by-product in the coal coking industry with a high output, is a low-cost and high-carbon yield precursor for the manufacturing of high-value carbon materials. Herein, N/O co-doped carbon fiber (CFCP), fabricated by electrospinning using pre-oxidized coal pitch as the precursor, was employed as the sulfur host for Li-S batteries. The presence of more pyrrolic N and graphic N in CFCP than carbon fiber made from polyacrylonitrile benefits the adsorption of lithium polysulfide and the battery’s life. Sulphur-CFCP cathode (S@CFCP) exhibited excellent specific capacity and cyclability, with a specific capacity of 701.1 mAh/g and a low capacity decay rate of 0.088% per cycle over 200 cycles at 2.0 C, respectively. The high ion diffusion rate, low charge transfer resistance, and effective conversion of lithium polysulfides enable the high electrochemical performance of S@CFCP.

Controlling surface chemistry in cold sintering to advance battery materials

Cold sintering is a recently introduced densification method that is of interest due to the lower energy used in the process, the ability to densify metastable materials, the ability to integrate materials to develop unique composites, and the ability to synthesis materials that can be more easily recycled. Collectively, these advantages make cold sintering a promising approach for processing of battery components, and co-sintering into all solid-state batteries. To obtain high electrochemical performance with cold sintering, detailed control of the surface chemistry of powders is needed, to avoid or minimize the impact of carbonate formation in grain boundaries, and to limit concentrations of secondary phases that are a result of incongruent dissolution processes. In this paper, we outline the importance of surface chemical reactions of powders in cold sintering, and the mitigating processes that can be adopted to control these reactions and obtain high performance and unique opportunities for Li and Na-oxide secondary batteries. We focus on a series of examples that demonstrate how the control of low temperature densification (cold sintering) can address the environmental sensitivity of many battery materials, and highlight the issues faced and open questions. These examples include cold sintering of air-sensitive solid electrolytes, re-processing of crushed solid electrolytes, surface passivation of air-sensitive active materials for processing in air, and fabrication of solid-solid macroscopic interfaces for solid-state batteries.

Wet spun cellulose nanocrystal/MXene hybrid fiber regulated by bridging effect for high electrochemical performance supercapacitor

Wet spun cellulose nanocrystal/MXene hybrid fiber regulated by bridging effect for high electrochemical performance supercapacitor

Controlling lithium cobalt oxide phase transition using molten fluoride salt for improved lithium-ion batteries

LiCoO2 is a historic lithium-ion battery cathode that continues to be used today because of its high energy density. However, the practical capacity of LiCoO2 is limited owing to the harmful phase transition at high voltages, which prevents the realization of its theoretical capacity. Here, we treat LiCoO2 particles with a molten salt of MgF2–LiF as a reaction accelerator to facilitate the diffusion and doping of magnesium into bulk LiCoO2 and to form a stable coating layer on the particle surface. Ex situ X-ray diffraction analysis confirms the inhibition of the harmful phase transition and the emergence of a different phase as the modified LiCoO2 was charged up to 4.7 V. The modified LiCoO2 shows high electrochemical performance during high-voltage operation. This technology provides a guideline for the suppressing fundamental degradation associated with phase transition and achieving ultra-high energy density LiCoO2 cathodes.

Preparation of manganese/nitrogen-sulfur carbon electrodes from black liquor of bamboo pulp for supercapacitors

Biomass-derived porous carbons from low-cost lignin are the promising candidate electrode for aqueous supercapacitors. Notably, the poor charge storage ability severely hinders the industrial production. The sodium lignosulphonate was firstly prepared by methylsulfonation with formaldehyde (HCHO) and sodium sulfite (Na2SO3). Then, lignin-based N-S co-doped porous carbon materials (LNSC) were prepared via one-step carbonization with sodium lignosulphonate as raw material and urea as a nitrogen source dopant and mild activator. And, MnCO3 nanowires were prepared and loaded on LNSC to fabricate manganese/nitrogen-sulfur carbon composites (LNSC/Mn-x) with high electrochemical performance. The prepared LNSC/Mn-40 was dominated by micro-mesopores with a total pore volume of 1.01 cm3 g−1 and a specific surface area of up to 770.68 m2 g−1. In a three-electrode system, LNSC/Mn-40 showed a specific capacitance of 234.92 F g−1 at 0.5 A g−1 in 6 M KOH electrolyte, greatly better than LNSC (151.98 F g−1 at 0.5 A g−1), while the symmetric supercapacitor demonstrated a maximum energy density of 7.21 Wh kg−1 at a power density of 5765 W kg−1 along with good cycling stability of 69.77 % capacitance retention for up to 10,000 cycles. The results suggested that lignin can be considered as an ideal candidate for porous carbon electrode for supercapacitors and reduce industrial production cost.

Synthesis Pathway of Layered-Oxide Cathode Materials for Lithium-Ion Batteries by Spray Pyrolysis.

We report the synthesis of LiCoO2 (LCO) cathode materials for lithium-ion batteries via aerosol spray pyrolysis, focusing on the effect of synthesis temperatures from 600 to 1000 °C on the materials' structural and morphological features. Utilizing both nitrate and acetate metal precursors, we conducted a comprehensive analysis of material properties through X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Our findings reveal enhanced crystallinity and significant oxide decomposition within the examined temperature range. Morphologically, nitrate-derived particles exhibited hollow, spherical shapes, whereas acetate-derived particles were irregular. Guided by high-temperature X-ray diffraction (HT-XRD) data, the formation of a layered LCO oxide structure, with distinct spinel Li2Co2O4 and layered oxide LCO phases was shown to emerge at different annealing temperatures. Optimally annealed particles showcased well-defined layered structures, translating to high electrochemical performance. Specifically, nitrate-based particles annealed at 775 °C for 1 h demonstrated initial discharge capacities close to 179 mAh/g, while acetate-based particles, annealed at 750 °C for 3 h, achieved 136 mAh/g at a 0.1C discharge rate. This study elucidates the influence of synthesis conditions on LCO cathode material properties, offering insights that advance high throughput processes for lithium-ion battery materials synthesis.

Pecan Shell-Derived Activated Carbon for High-Electrochemical Performance Supercapacitor Electrode.

Carbon nanomaterials-based electric double-layer capacitors (EDLCs) are reliable and appealing energy-storage systems offering high power density and long cycling stability. However, these energy storage devices are plagued with critical shortcomings, such as low specific capacitance, inefficient physical/chemical activation process, and self-discharge of electrode materials, hindering their future application. In this work, we use a self-activation process, an environmentally benign and low-cost process, to produce high-performance activated carbon (AC). Novel activated carbon from pecan shells (PS) was successfully synthesized through a single-step self-activation process, which combines the carbonization and activation processes. The as-synthesized pecan shell-derived activated carbon (PSAC) provides a high-porosity, low-resistance, and ordered pore structure with a specific pore volume of 0.744 cm3/g and BET surface area of 1554 m2/g. The supercapacitors fabricated from PSAC demonstrate a specific capacitance of 269 F/g at 2 A/g, excellent cycling stability over 15,000 cycles, and energy and power density of 37.4 Wh/kg and of 2.1 kW/kg, respectively. It is believed that the high-efficiency PSAC synthesized from the novel self-activation method could provide a practical route to environmentally friendly and easily scalable supercapacitors.

Growth of octahedral structured AgBiS2 single crystals and its insights on the high performance electrocatalytic hydrogen generation

Given the enormous depletion of fossil fuels and growing environmental concerns, there is an immediate need to develop alternative and clean energy sources. Hydrogen (H2), recognized for its cleanliness and renewability, is poised to meet future energy requirements. Consequently, ongoing research is focused on the development of electro-active, durable, and cost-effective catalysts to replace expensive noble metal-based electrocatalysts. In this study, microscale AgBiS2 chalcogenide derived from a single crystal is reported as promising electrocatalysts for the Hydrogen Evolution Reaction (HER) with a remarkably low overpotential. The physico-chemical characterization of the AgBiS2 catalyst has been investigated using various analytical techniques. The synthesized AgBiS2 catalyst exhibits excellent HER activity, manifesting a low overpotential of 86 mV at a current density of 10 mA cm−2 and a Tafel slope of 44 mV dec−1, along with superior stability even after 24 h in HER at a very high current density. The developed AgBiS2 also showcased stable production when subjected to a two-electrode system. The enhanced alkaline HER activity of AgBiS2 can be attributed to its phase purity, high crystallinity, and the presence of high active sites. The observed high electrochemical performance and stability position AgBiS2 as a potential electrocatalyst for the hydrogen evolution reaction. This finding holds significant promise in the quest for efficient, durable, and economically viable catalysts to drive the shift towards clean and renewable energy sources.

One-step production of peanut shell derived N, P co-doped carbon materials for high-performance symmetric supercapacitors

In order to realize the reuse of agricultural waste and improve the electrochemical performance of carbon materials, N and P co-doped carbon materials were prepared by using rich and cheap waste peanut shells as carbon precursors and NH4H2PO4 as N and P sources. The effects of the mass ratio of peanut shell and NH4H2PO4 on the structure, composition, morphology and electrochemical properties of carbon materials were studied in detail. The results show that when the mass ratio is 2:3, the prepared PSC-3 has the largest surface area and higher heteroatom content, which provides a structural basis for its high electrochemical performance. Electrochemical tests show that the specific capacitance of PSC-3 at 1 A g−1 can reach 184 F g−1, and has excellent rate performance. When the mass ratio is higher than or below 2:3, the electrochemical performance of carbon materials will be reduced, demonstrating the feasibility of achieving the best electrochemical performance by adjusting the amount of NH4H2PO4. In addition, the symmetric supercapacitor (SSC) assembled by PSC-3 can obtain an energy density of 10.1 Wh kg−1, which has excellent energy storage characteristics.

Synthesis and electrochemical properties of activated lignite carbons-reduced graphene oxide nanocomposites symmetric supercapacitors

Ultra-fast chargeable or rechargeable symmetric carbon-based supercapacitors (SCSs) with high capacity, inexpensive, and non-flammability have attracted much attention for electronics and energy storage devices. However, improving both high redox reaction and ion transport/diffusion processes by enhancing high energy storage performance and rapid ion/electron transport SCSs electrode materials remains challenging. Herein, we presented a successful preparation of activated lignite carbons-reduced graphene oxide (ALC-rGO) nanocomposite (NCp) with the ALC:rGO ratio of 80:20 wt% by a one-pot hydrothermal for high electrochemical performance. Importantly, the matrix of ALC-rGO NCp was primary amorphous carbon with hexagonal graphitic layers and pore structures of plentiful micropores and mesopores. Remarkably, the ALC-rGO NCp electrode exhibited a maximum specific capacitance (Csc) of 152.12 F/g at 0.5 A/g. Interestingly, the SCSs-ACL-rGO device could illustrate a good performance at a potential voltage of 1.8 V with Csc of 50.90 F/g at 1 A/g and capacity retention of 96.0 % at 5 A/g after 2,000 cycles GCD test.

Highly efficient electrocatalytic degradation of methylparaben using BiOx-doped Ti/β-PbO2 anode: Comprehensive electrochemical study and degradation mechanism

Electrochemical degradation of methylparaben (MPB) was successfully performed using Ti/β-PbO2-BiOx anode. The structure of the fabricated electrode was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and mapping techniques. The results confirmed the successful preparation of the electrode with favorable morphological and structural properties. This research includes optimization of operating parameters such as solution pH, applied current density, initial MPB concentration and electrolysis time. The results indicate that the prepared electrode has high electrochemical performance and thermal stability. Under optimal conditions, current density of 4.8 mA/cm2, pH = 5 and initial concentration of 0.5 mM, the maximum degradation efficiency of 98.9 % was obtained. In this work, also, based on the data obtained from LC-MS analysis, a detailed mechanism for the degradation of MPB was proposed. In another section of this research, the electrochemical behavior of MPB on glassy carbon electrode was comprehensively studied using cyclic voltammetry at different pH values. The data obtained from this study provide significant insight into the electrochemical behavior of MPB, its pH-dependent properties and adsorption activities. The results of this section can also be used to better optimize the conditions of MPB degradation.

Empowering lithium-ion batteries: The potential of 2D o-Al2N2 as an exceptional anode material through DFT analysis

Finding an appropriate new anode material with high electrochemical performance for lithium-ion batteries (LIBs) is considered one of the significant challenges for both the academic and industrial research communities. Herein, we propose to explore the efficiency of a newly designed two-dimensional (2D) material, named orthorhombic dialuminium dinitride (o-Al2N2), as an alternative anode material for LIB systems through first-principles calculations and ab initio molecular dynamics (AIMD) simulations. The obtained results show that orthorhombic-Al2N2 exhibits a high specific capacity of 1144.2913 mAhg−1, an operating voltage around 0.575 V, and a low kinetic diffusion barrier of 0.26 eV. These results prove the suitability of the o-Al2N2 monolayer as a promising anode material for LIBs with high structural stability, strong binding energy towards lithium adsorbent, fast lithium diffusion, and a high theoretical capacity. These features rank the 2D o-Al2N2 monolayer among the best choices for the anode part of the next-generation rechargeable LIBs.

Novel NASICON-type Mn0.5Ti2(PO4)3@F-doped carbon composite with high electrochemical performance as anode materials for potassium-ion batteries

Mn0.5Ti2(PO4)3 with a NASICON structural is used as an anode material in potassium-ion batteries due to its abundance of vacancies that can hold potassium ions. This characteristic not only contributes to its excellent stability but also results in a high specific capacity. However, the poor electrical conductivity of the polyanionic type structure limits the material's ability to fully utilize its capacity. In this paper, the conductivity and electrochemical stability of the Mn0.5Ti2(PO4)3 anode material are enhanced through composite formation with an F-doped carbon layer. The introduction of F into the carbon matrix creates a large number of vacancy defects and F active sites. The vacancies enhance the transport of potassium ions on the Mn0.5Ti2(PO4)3 material's surface, while the active sites exhibit strong electronegativity, improving the absorption of potassium ions. Therefore, the diffusion impedance of potassium ions is significantly reduced, leading to an increased diffusion rate of potassium ions. Attributing to the improved reaction kinetics, the Mn0.5Ti2(PO4)3@F-doped carbon composite demonstrates a high specific capacity of 86 mA h g−1 at 10,000 mA g−1 when used as the anode for potassium-ion batteries. Even more, the specific capacity remains a capacity of 136 mA g−1 after 3000 cycles at 1000 mA h g−1. This study enhances our comprehension of material design by investigating the alteration of carbon matrix to promote the electrochemical characteristics of materials.

Improving the rate and cycle performance of V-based cathodes through regulation of the Zn2+ desolvation process

The large-scale application of vanadium in AZIBs has been hampered by its inferior rate performance and cycling stability, arising from the desolvation penalty of Zn2+ and the dissolution of vanadium. To address this issue, hydroxymethyl zinc phosphates Zn(O3PCH2OH) (ZnOPC) have been innovatively employed as a cathode electrolyte interphase (CEI) material to enhance the electrochemical performance of V2O5·nH2O (VO) cathode. The organized path structure of ZnOPC, coupled with its numerous hydroxyl groups, significantly reduces the desolvation penalty of Zn[H2O]62+ by forming new hydrogen bonds with the solvent-shell water molecules. More importantly, ZnOPC effectively mitigates vanadium dissolution by immobilizing free H2O which comes from the desolvation of Zn[H2O]62+. Consequently, the modified VO cathode exhibits superior rate performance and extraordinary cycling life, maintaining a specific capacity of 202.7 mAh/g after 7000 cycles at 10 A/g and 238.1 mAh/g at the high current of 20 A/g. These results offer a new prospect for designing high electrochemical performance vanadium-based cathode for AZIBs.

Exploring new solid electrolyte support matrix materials for molten carbonate fuel cells (MCFCs)

New oxide ion conductors with perovskite structures containing alkali metal were explored for use as solid support materials for MCFCs (molten carbonate fuel cells). The conductivity of two candidates, BNT (0.94Bi0.5Na0.5TiO3-0.06BaTiO3) and LNT (La0.5Na0.5TiO3), in an oxidation atmosphere, were measured and compared. The conductivity measurement of BNT in a reducing atmosphere indicated the reduction of BNT to Bi metal by a sharp change in conductivity. It limited the lifetime of the fuel cell using BNT as solid support. Fuel cell measurements using the alternative perovskite LNT showed excellent stability under fuel cell operation conditions and high-power density compared to conventional MCFC with LiAlO2 as the solid matrix. The reason for obtaining high electrochemical performance using the LNT matrix is discussed.

Electrochemical performance of V2O5/TiO2 nanocomposite: As an emerging electrode material for supercapacitor application

This scrutiny encounters the hydrothermal approach of binary nanocomposites V2O5/TiO2 (VT). The XRD pattern substantiated the formation of the binary composites with 18 nm of the crystallite size without any extraneous impurities. Whereas, HR-SEM implies the efficient bonding and homogeneous distribution between V2O5 and TiO2 nanoparticles, which provokes high electrochemical performances. Additionally, the BET analysis exposes the specific surface area to be 251 m2 g−1 with an average pore size of 3.14 nm for the VT nanocomposite. The electrochemical performances of the binary VT nanocomposite exhibit high specific capacitance of 443.7 Fg−1 at a current density of 1 Ag−1 with an excellent cyclic retention of 90 % even after successive 5000 cycles at 5 Ag−1. Therefore, the results obtained in this study clearly demonstrates that the binary nanocomposite VT would be a favorable electrode material for the commercial energy storage applications.