Excellent Electrochemical Performance Research Articles

Fabrication of Fe/KB Composite as Sulfur Host for Li-S Battery.

Lithium sulfur battery is a novel kind of secondary battery which has high energy density, however its application is greatly affected by the shuttle effect of polysulfides generated in the redox reaction of cathode electrode. Metal active sites are supposed as effective catalysts which can absorb and accelerate the conversion efficiency of lithium polysulfides, thus the shuttle effect will be alleviated. In this work, we conducted a simple way to prepare a metal Fe doped ketjen black to serve as the sulfur host of lithium sulfur battery. Ketjen black has a large specific surface area and rich porous structure, while Fe nanodot is an excellent catalyst for lithium polysulfides. Because of these advantages, the Fe/KB host can effectively confine a large amount of active material and accelerate its, therefore the Fe/KB-S cathode electrode show an excellent electrochemical performance.

Preparation of biomass-derived activated carbon from golden needle mushroom roots for supercapacitor electrodes

Herein, an original activated carbon (AC) is prepared using golden needle mushroom roots and potassium hydroxide. After carbonization under 500 °C, AC-5 exhibits good graphitization degree, appropriate nitrogen and oxygen elements, large specific surface area, and micro-meso porous structures. Notably, AC-5 as electrodes in supercapacitors has excellent electrochemical performances, e. g. high specific capacitance (360.4 F/g), impressive rate capability (77 %, from 10 mV/s to 200 mV/s), and outstanding cycling durability (99.56 %, after 10,000 cycles).

Guanine-derived core-shell FeCo alloy confined in graphene-like N-doped carbon as efficient bifunctional oxygen electrocatalysts for rechargeable Zn-air batteries

Maximization the synergistic effect of each component in transition metal-carbon complexes is expected to improve the bifunctional oxygen electrocatalysis for rechargeable Zn-air batteries but is still challenging. Herein, nucleobase guanine is employed as a supramolecular precursor to generate the core (FeCo alloy)-shell (carbon) structure embedded in ultrathin graphene-like nitrogen-doped carbon nanosheets (FeCo@NCNSs) via a confinement pyrolysis strategy. Thanks to the generated core-shell structure and bimetallic synergistic effect, the as-prepared FeCo@NCNSs exhibits excellent electrochemical performance in both oxygen reduction reaction and oxygen evolution reaction. As a result, when served as the bifunctional air electrode for a practical Zn-air battery, FeCo@NCNSs exhibits a higher open-circuit voltage (1.553 V) and peak power density (197.30 mW cm−2), as well as the greatly improved long-term cyclic stability compared to the noble metal benchmarks. This work provides a promising approach to integrate various active sites for bifunctional oxygen electrocatalysis and inspires the exploration of simple but efficient electrocatalysts for energy storage and conversion.

An ultrasensitive electrochemical sensor based on boron-doped porous graphene for efficient detection of nitrite in food

Boron (B) doping plays a critical role in adjusting the electronic properties of carbon materials. In this work, B-doped porous graphene (B-PG) was successfully prepared by a simple strategy and used as an advanced electrode material for the detection of nitrite (NO-2) in food. The scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize this B-PG. Due to the ideal doping of boron atoms, the material has good conductivity and exhibits excellent electrochemical catalytic performance. NO-2 was used as the representative analytes to demonstrate the sensing performance of B-PG. It is found that the B-PG modified GCE exhibited a linear response over the concentration range from 3 μM – 3 mM and 3 mM – 15 mM, with a detection limit of 1.1 μM. The designed electrochemical sensor has good analytical performance, such as high sensitivity, good reproducibility and acceptable accuracy, and can be successfully applied to the accurate and precise detection of residual NO-2 in food.

Pyrolysis of spent coffee grounds dispersed clay in N2: Production of type-II conductive ceramics with electrochemical performance

Pyrolysis of spent coffee grounds dispersed clay in N2 produces type-II conductive ceramics with electrochemical performance. Protective atmosphere and surface screening play important roles in converting spent coffee grounds into carbon coatings on ceramic surfaces; the former prevents oxidation of organic ingredients and confinement of pyrolysis in clay for the latter. Selective-area electrical measurements indicate resultant ceramics to be conductive and interconnected carbon coatings are further verified by SEM inspections and consistency between thermal conductivity and diffusivity. Conductive ceramics show a high usage of surface area by electric double layer charging mechanism thus giving an excellent electrochemical performance.

Ni-rich LiNi0.905Co0.043Al0.052O2 cathode material for high-energy density Li-ion cells: Tuning lithium content, structural evolution, and full-cell performance

Ni-rich LiNi0.905Co0.043Al0.052O2 oxides with the Li excess (x) up to 7 mol.% used in the synthesis are prepared by a facile dry-mixing method. It is shown that the Li/Ni mixing level and crystallite size are dependent on the Li amount, while Al from the precursor acts as a scavenger of the excessive Li. Operando X-ray diffraction (XRD) studies enable explaining differences in the structural evolution of materials exhibiting high and low Li/Ni mixing, especially in the H2↔H3 transition region. Soft X-ray absorption spectroscopy (XAS) studies show differences in the charge state evolution of the surface and bulk Ni. The optimized oxide with the Li excess x = 2 mol.% delivers excellent electrochemical performance, with an initial discharge capacity of 205.5 mAh g−1 at 0.1C, and 91.4 % capacity retention after 100 cycles at 1C. The unmodified in any other way cathode material allows achieving the discharge capacity of 178.5 mAh g−1 at the high rate of 5C, and works well in the full-cells.

Dendrite-free Zn anode enabled by combining carbon nanoparticles hydrophobic layer with crystal face reconstruction toward high-performance Zn-ion battery

Aqueous zinc ion batteries (ZIBs) have been considered promising energy storage systems due to their excellent electrochemical performance, environmental toxicity, high safety and low cost. However, uncontrolled dendrite growth and side reactions at the zinc anode have seriously hindered the development of ZIBs. Herein, we prepared the carbon nanoparticles layer coated zinc anode with (103) crystal plane preferential oriented crystal structure (denoted as C@RZn) by a facile one-step vapor deposition method. The preferential crystallographic orientation of (103) crystal plane promotes zinc deposition at a slight angle, effectively preventing the formation of Zn dendrites on the surface. In addition, the hydrophobic layer of carbon layer used as an inert physical barrier to prevent corrosion reaction and a buffer during volume changes, thus improving the reversibility of the zinc anode. As a result. the C@RZn anode achieves a stable cycle performance of more than 3000 h at 1 mA cm−2 with CE of 99.77 % at 5 mA cm−2. The full battery with C@RZn anode and Mn-doped V6O13 (MVO) cathode show stability for 5000 cycles at the current density of 5 A g−1. This work provides a new approach for the design of multifunctional interfaces for Zn anode.

The role of nanoporous carbon materials for thiophosphate-based all solid state lithium sulfur battery performance

Due to their high theoretical energy density, all solid state lithium sulfur batteries (LS-SSB) represent one of the most promising candidates for next-generation energy storage systems. Whilst high sulfur utilizations have been published for several cathode compositions and preparation methods in recent years, there is still a lack of clarity regarding the influence of the used carbon. Furthermore, LS-SSBs face challenges in up-scaling as the common preparation methods including high energy ball milling are time consuming, batch-wise and need high energy impact. In this study, high sulfur utilization >1600 mAh gS−1 and reversibility with 80 % of initial discharge capacity after 60 cycles is achieved, using a more time-efficient preparation method with drastically lowered energy impact by selecting a suitable carbon. Additionally, the influence of the carbon nanostructure on the electrochemical performance is discussed. This study provides guidance in selecting nanostructured carbon materials to enable cost-efficient, up-scalable preparation methods for LS-SSBs without compromising on the excellent electrochemical performance.

Anion trapping-coupling strategy driven asymmetric nonflammable gel electrolyte for high performance sodium batteries

Gel polymer electrolytes, promising electrolyte candidates for advanced sodium metal batteries (SMBs), suffer from the great challenges of combustion risk and inferior interfacial stability caused by poor mechanical properties and low Na+ selectivity. Herein, we proposed a rational anion trapping-coupling strategy to build a mechanically robust asymmetric nonflammable composite gel electrolyte (AS-NFCGE) by introducing in-situ coupled boron nitride nanosheets (BNNs) on glass fiber matrix embedded with synchronous polymerized flame-retardant polymer. Theoretical calculations, finite-element simulations, and experimental tests prove that the high coupling BNNs with anion trapping effect constructed asymmetric structure can significantly accelerate selective Na+ migration kinetics, enhance mechanical properties of AS-NFCGE and endow a similar single-ion conducting behavior to homogenize ion-distribution at the anode side, thus improving interfacial stability and suppressing dendrite growth to achieve ultra-stable SMBs. Specifically, the AS-NFGE delivers high ionic conductivity and Na+ transference number (0.73) together with excellent flam-retardant. Consequently, the dendrite-free Na/Na symmetric cell exhibits considerable cycling life for over 3000 h at 0.1 mA cm−2 with low overvoltage. Applications of the AS-NFCGE in SMBs further demonstrate the excellent electrochemical performances, and no thermal runaway and no electrolyte leakage occur for pouch cells using AS-NFCGE. This strategy provides new insight into the development of safe and high-energy SMBs and the beyond.

Guiding lithium growth direction by Au coated separator for improving lithium metal anode

Lithium metal is the most promising anode for next-generation batteries due to its highest theoretical capacity and lowest electrochemical potential. However, its dendritic growth hinders its practical use due to the consequent poor reversibility, potential short-circuit, and safety concerns. Suppressing lithium dendrite is difficult since dendritic growth is thermodynamically and kinetically favorable. Herein, we guide lithium to uniformly deposit along the opposite direction to normal by a nanolayer Au coating on a commercial polypropylene separator. It prevents lithium dendrites from piercing the separator, instead of inhibiting dendrites growth only. Au is lithiophilic, and lithium is calculated to be more attracted to Au and is confirmed to uniformly deposit on Au at the separator side rather than on the current collector side. Furthermore, Au also regulates the morphology of deposited lithium from a mossy state to a bulky state. In this work, the symmetric cell with the designed structure achieves excellent electrochemical performances of a long-life cycle over 2,000 h at 1 C for 1 mA h cm-2. Pairing with LiFePO4 cathode as a full cell, lithium metal anode with Au-modified polypropylene separator exhibits extraordinary performance with a high Coulombic efficiency of 99.23% over 800 cycles at 1 C.

Thiocarbamide conversion-based nitrogen-rich covalent organic framework coatings for electro-enhanced solid-phase microextraction of bisphenols

Design and preparation of fiber coatings with excellent electrochemical performance and high polarity is significant for efficient extraction of polar targets in electro-enhanced solid-phase microextraction (EE-SPME). In this work, a combination strategy for structure regulation of covalent organic framework (COF) was proposed to fabricate a nitrogen-rich thiocarbamide linked COF coating (Thiocarbamide-TZ-DHTP) via molecular design and post-synthetic thiocarbamide conversion. The prepared COF coating possesses a large number of O, N, and S functional groups, which not only endow the coating with higher polarity but also significantly enhance its electrochemical performance. The COF coating was used for EE-SPME of polar bisphenols (BPs), demonstrating excellent enrichment efficiency and durability. Subsequently, coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS), a sensitive method was developed for determination of trace BPs. The established method possess wide linear ranges (2.0–800.0 ng L−1), good correlation coefficients (0.9985–0.9994) and low detection limits (0.1–2.0 ng L−1). Moreover, the established method had been successfully applied to detection of trace BPs in tea beverage with satisfactory recoveries (81.6 % to 118.6 %). This research provides a feasible pathway for preparing COF coating with excellent electrochemical performance and high polarity for EE-SPME.

Synthesis and Catalytic Performance of Mo2C/MoS2 Composite Heterojunction Catalysts.

Hydrogen, as a clean, safe, and efficient energy carrier, is one of the hot energy sources that have attracted much attention. Mo2C, due to the introduction of C atoms, makes the atomic spacing of the Mo lattice decrease and changes the width of the d-band, which makes the electronic properties of Mo2C similar to that of Pt noble metals, exhibiting excellent electrochemical hydrogen precipitation performance. MoS2, due to its special crystal structure and tunable electronic structure, has been widely studied. In this paper, Mo2C nanoparticles were prepared by high-temperature carbonization, and then two-dimensional layered MoS2 were be loaded on Mo2C nanoparticles by the hydrothermal method to synthesize Mo2C/MoS2 composite catalysts. Their electrochemical hydrogen precipitation (HER) performance under acidic conditions was tested. The above catalysts were also characterized by modern material testing methods such as XRD, SEM, TEM, and XPS. The results showed that the composite catalysts exhibited the most excellent electrochemical hydrogen precipitation performance at Mo2C/MoS2-3, with the lowest overpotential at a current density of 10 mA cm-2, Tafel slope, and electrochemical impedance. At the same time, the electrochemically active area was dramatically enhanced, with good stability under prolonged testing. The catalytic activity was significantly improved compared with that of Mo2C and MoS2. The characterization and experimental results indicate that the heterogeneous structure of Mo2C and MoS2 formed a built-in electric field between the two, which accelerated the electron transfer efficiency and provided more active sites. The Mo2C/MoS2 composite catalyst is a low-cost, easy-to-prepare, and high-efficiency electrochemical hydrogen precipitation catalyst, providing a new idea for developing green and clean energy.

In-situ conversion method for Co9S8 embedded in N-doped carbon derived from resin waste induced ultra-stable Li-S batteries

The effective suppression of the shuttle effect in lithium-sulfur batteries require the development of efficient electrocatalysts. Transition metal sulfides show great potential as S cathode electrocatalysts. However, the conventional secondary sulfidation or heat-treatment process used in their synthesis limits their catalytic performance. In this study, we propose an efficient and scalable “exchange-constriction-in-situ conversion” strategy to prepare Co9S8@NC electrocatalysts using CoSO4 and waste resins as sources. No additional sulfur source is required in this process. The resulting Co9S8@NC catalyst demonstrates outstanding long-cycle performance, with a slight decay of only 0.028 % per cycle after 500 cycles at a current density of 2 C. Moreover, it exhibits excellent electrochemical performance even at high surface loading and low electrolyte dosage (E/S). The combination of theoretical calculations and electrochemical analyses demonstrates that Co9S8 possesses strong adsorption, superior catalytic capacity and lower energy barrier of decomposition towards lithium polysulfide, consequently leads to an enhancement in reaction kinetics. This study presents a novel approach for synthesizing high-performance sulfide electrocatalysts.

Dual functionality of NiFe2O4 nanoparticles as a fertilizer and supercapacitor

Nanoparticles-based fertilizers can supply nutrients more effectively to the crops that can improve agricultural productions. Ferrite nanoparticles can replace the conventional iron fertilizers. Iron is more essential for plant growth and itsdeficiency mostly affects the cellular activities. Nickel isa constituent of plant enzymes like urease that converts nitrogen into useable ammonia inside the plant. It also prevents the accumulation of toxic levels of urea in plant tissues. In spinel ferrites, Nickel ferrite is considered for many applications because of its superior properties. NiFe2O4nanoparticles exhibit excellent electrochemical performance with highest capacity. NiFe2O4 nanoparticle (NP) has been successfully synthesized using sol–gel technique and its characteristics are analysed by XRD, FTIR and SEM techniques. XRD confirms the cubic-spinel structure with crystallite size of 23.98 nm. FT-IR spectrum shows the presence of functional groups in the sample. The SEM images shows the morphology and size of the obtained nanoparticles. The results of seed priming account of nickel ferrite NPs in the growth of rice and black gram have been explored. Seeds of rice and black gram are primed with various concentrations of NiFe2O4 NPs (0, 5, 10, 15, and 20 mgL−1) for 24 h by continuous aeration. Plant height, spike length, dry weights of roots, shoots, grains, and spikes are greater with synthesized NPs, especially in higher rates of NPs. The results confirm that NiFe2O4 NPs made significant influence in the growth of rice and black gram. NiFe2O4 NPs are developed as electrode for supercapacitor and tested their charge storage ability by the electrochemical techniques. It exhibits specific capacitance of 360 Fg−1 and cyclic retention of 98.9 % even after 5000 GCD cycles. Bifunctional performance of NiFe2O4 NPs is demonstrated as nano fertilizer and supercapacitor which is the need for fertilizer and energy storage devices industries.

Porous Structure‐Electrochemical Performance Relationship of Carbonaceous Electrode‐Based Zinc Ion Capacitors

Porous Structure‐Electrochemical Performance Relationship of Carbonaceous Electrode‐Based Zinc Ion Capacitors

Polymer solid electrolytes with ultra-stable cycles and high-capacity retention for all-solid-state Li-metal battery

Polymer electrolytes have become widely popular on account of their low expenses, reduced weight, simple processing, and excellent safety features. However, polymer electrolytes have yet to find use in commercial batteries because of their limited mechanical durability and poor ionic conductivity. In this paper, an ultra-stable cycles and interfaces blending polymer electrolyte (BPE) suitable for all solid-state Li metal batteries was prepared by blending three polymers: polymethyl methacrylate (PMMA), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), and polyethylene oxide (PEO). Microstructure characterization showed numerous amorphous areas with strong interfacial strength of the BPE. The BPE3 exhibited a maximum of 15.65 MPa in tensile strength. BPE2 have excellent electrochemical performance, such as wide electrochemical windows (up to 4.7 V vs Li/Li+), high lithium ion transference numbers (up to 0.75), high ion conductivity (up to 1.87 × 10-4 S cm−1 at 60 °C), and excellent interface stability. By assembling all state-solid LiFePO4/BPE2/Li batteries for electrochemical testing, BPE2 exhibit high electrochemical characteristics. BPE2 discharge specific capacity is as high as 154.7 mAh g−1 at 1C. The BPE2 underwent 200 cycles at 0.5C and 400 cycles at 1C, with capacity retention rates of 95.7 % and 96.6 %, respectively. BPE is a promising electrolyte candidate for flexible lithium metal batteries.

Ternary systems engineered conductive hydrogel with extraordinary strength, environmental adaptability and excellent electrochemical performances for flexible power supply devices

The easy failure, poor environmental adaptability and unsatisfactory electrochemical performances of hydrogels hinder their applications as key components of flexible power supply devices (PSDs). Herein, a PAA-based hydrogel with extraordinary strength and environmental adaptability is designed via a ternary system, consisting of the tannin-modified MXene (TA@MXene), ZnCl2-cellulose and malic acid (MA) electrolyte. The TA@MXene and ZnCl2-cellulose promote the crosslinking of hydrogel via forming multi networks, endowing the hydrogel with 1.9 MPa tensile strength and 620 % stretchability. Furthermore, the hydrogel has 38.4 mS·cm−1 conductivity, thanks to the effective ion transfer channels in the hydrogel. The MA electrolyte provides a stable pH environment via forming an acid ionization system; also, MA and the high-concentration ZnCl2 solution enhance their electrochemical performance at extreme environments. Three typical PSDs were assembled using the resultant hydrogel as electrolyte/electrode. The as-prepared supercapacitors display a high specific capacity (173.5 mAh·g−1), a superior energy density (208.2 Wh·kg−1) and outstanding capacity retention (92.1 % after 5000 cycles); flexible batteries efficiently respond to strain signals, with 0.77 V open-circuit voltage (Voc); the as-assembled TENG has a 110 V Voc (100 % stretching deformation). We present a design strategy for the construction of advanced hydrogels based a ternary system that will promote flexible PSDs towards practical use.

Synthesis and application of anthraquinone quaternary phosphonium salt electroplating copper leveler based on expanded electrostatic adsorption area strategy and physicochemical salt bridge mechanism

Four anthraquinone quaternary phosphate molecules (AQS-a, AQS-b, AQS-c, AQS-d) with different electrostatic adsorption areas were constructed as electroplating levelers based on the strategy of expanding the electrostatic adsorption area of the molecules. AQS-d with the largest electrostatic adsorption area was demonstrated to have the most excellent electrochemical performance by electrochemical tests. The physicochemical adsorption sites and interactions with copper ions of AQS levelers were proposed by theoretical calculations, molecular dynamics simulations, Raman spectroscopy and fluorescence absorption spectroscopy, and the electroplating salt bridge mechanism was proposed. Based on optical microscope, scanning electron microscope, atomic force microscope and X-ray diffractometer, it is proved that AQS-d has the ability to perfectly fill the microvia in actual plating by actual PCB blind hole filling experiment.

Amphoteric Supramolecular Nanofiber Separator for High‐Performance Sodium‐Ion Batteries

The separator is an essential component of sodium‐ion batteries (SIBs) to determine their electrochemical performances. However, the separator with high mechanical strength, good electrolyte wettability and excellent electrochemical performance remains an open challenge. Herein, a new separator consisting of amphoteric nanofibers with abundant functional groups was fabricated through supramolecular assembly of natural polymers for SIB. The uniform nanoporous structure, remarkable mechanical properties and abundant functional groups (e.g. −COOH, −NH2 and −OH) endow the separator with lower dissolution activation energy and higher ion migration numbers. These metrics enable the separator to lower the barrier for desolvation of Na+, accelerate the migration of Na+, and generate more stable solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI). The battery assembled with the amphoteric nanofiber separator shows higher specific capacity and better stability than that assembled with glass fiber (GF) separator.

Unveiling the CoFe LDH generated by partial in situ conversion strategy: Synergistic effect of modified MXene and cationic vacancies for overall water splitting

It remains a challenge to utilize non-precious metal electrocatalysts to increase intrinsic activity and observe more active sites. Herein, we propose a simple partial in situ transformation strategy to form a novel MOF@CoFe LDH heterostructure by Co-MOF template-directed fabrication using modified MXene as substrate, and introduce metal cation vacancy defects on the as-prepared LDH surface to further enhance the performance of the catalysts. Density-functional theory calculations show that the electron transfer rate of a material can be tuned by modulating the electron diffusion phenomenon, thereby lowering the energy barrier of the catalytic reaction. Consistent with the expected results, the catalysts also showed excellent electrochemical performance with HER and OER reaching current densities of 10 mA cm−2 with overpotentials of only 201 mV and 197 mV, and Faraday efficiencies (FE) close to 100 %. Meanwhile, a cell overpotential of only 1.56 V is required to effectively drive a current density of 10 mA cm−2 in the two-electrode system, and the superior long-term stability of the material reveals its potential for cost reduction in large-scale industrial applications.