Electrochemically Surface-modified Aluminum Electrode Enabling High Performance and Ultra-long Cycling Life Al-ion Batteries

Innovation in electronic devices has created a demand for energy storage systems. Recently, rechargeable Al-ion batteries (AIBs) have received significant attention owing to their high gravimetric capacity and low cost. In this study, the electrochemical performances of pristine, etched, and electropolished Al negative electrodes via surface modification were investigated to determine their efficiency in AIBs. Herein, pristine, etched, and electropolished Al acted as the negative electrodes (anodes), and pure graphite and aluminum chloride (AlCl₃)/1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) were used as the positive electrode (cathode) and ionic liquid electrolyte, respectively. This new type of electropolished Al-based battery cell shows good cyclability and high performance compared to pristine and etched Al electrodes. The electropolished Al electrode stabilized at an average capacity of 50 mAh g⁻¹ over 10,000 cycles at an ultrafast current rate of 5,000 mA g⁻¹.     

New Multifunctional Porous Materials Based on Inorganic–Organic Hybrid Single‐Walled Carbon Nanotubes: Gas Storage and High‐Sensitive Detection of Pesticides

Single‐walled carbon nanotubes (SWNTs) that are covalently functionalized with benzoic acid (SWNT‐PhCOOH) can be integrated with transition‐metal ions to form 3D porous inorganic–organic hybrid frameworks (SWNT‐Zn). In particular, N₂‐adsorption analysis shows that the BET surface area increases notably from 645.3 to 1209.9 m² g^?1 for SWNTs and SWNT‐Zn, respectively. This remarkable enhancement in the surface area of SWNT‐Zn is presumably due to the microporous motifs from benzoates coordinated to intercalated zinc ions between the functionalized SWNTs; this assignment was also corroborated by NLDFT pore‐size distributions. In addition, the excess‐H₂‐uptake maximum of SWNT‐Zn reaches about 3.1 wt. % (12 bar, 77 K), which is almost three times that of the original SWNTs (1.2 wt. % at 12 bar, 77 K). Owing to its inherent conductivity and pore structure, as well as good dispersibility, SWNT‐Zn is an effective candidate as a sensitive electrochemical stripping voltammetric sensor for organophosphate pesticides (OPs): By using solid‐phase extraction (SPE) with SWNT‐Zn‐modified glassy carbon electrode, the detection limit of methyl parathion (MP) is 2.3 ng mL^?1.     

Identification of Non‐Carbonaceous Cathodes in Al Batteries: Potential Applicability of Black and Blue Phosphorene Monolayers

In the present era of growing energy demands, low‐dimensional materials are emerging as the suitable choices for energy storage due to their excellent ion transport properties, improved reversible capacity, fine rate performance and good cycling stability. In this context, we have investigated the applicability of black and blue phosphorene monolayers as potential cathodes for Al batteries. Both black and blue phosphorene monolayers show similar electrochemical behavior as that of experimentally reported graphite with a charge transfer from the surface in order to bind the tetrahedral geometry of AlCl₄ during the charging process. The adsorption of AlCl₄ drives semiconductor‐to‐metallic transformation of black/blue phosphorene, which ensures constant conductivity in Al batteries. Following the systematic adsorption of AlCl₄, the voltage for black and blue phosphorene is calculated to be ≈1.50 V and ≈1.80 V with storage capacities of 144 mAh g^?1 and 108 mAh g^?1, respectively. Besides, low diffusion barriers of 0.11 eV and 0.14 eV are predicted for AlCl₄ on the respective systems of black and blue phosphorene monolayers. Our work suggests that both black and blue phosphorene monolayers can be potential cathodes for Al batteries with delivery of high storage capacity and high voltage, respectively.     

Electorchemical Studies of Cytochrome c on Electodes Modified by Single—Wall Carbon Naotubes

Single-wall carbon nanotubes(SWNTs) modified gold electrodes were prepared by using two different methods.The electrochemical behavior of cytochrome c on the modified gold electrodes was investigated.The first kind of SWNT-modified electrode (noted as SWNT/Au electrode)was prepared by the adsorption of carboxylterminated SWNTs from DMF dispersion on the gold electrode.The oxidatively processed SWNT tips were covalently modified by coupling with amines (AET) to form amide linkage.Via Au-S chemical bonding,the self-assembled monolayer of thiol-unctionalized nanotubes on gold surface was fabricated so as to prepare the others SWNT-modified electrode (noted as SWNT/AET/Au electrode).It was shown from cyclic voltammetry cxperiments that cytochrome c exhibited direct electrochemical responses on the both electrodes, but only the current of controlled diffusion existed on the SWNT/Au electrode while both the currents of controlled diffusion and adsorption of cytochrome c occurred on the SWNT/AET/Au electrode.Photoelastic Modulation Infared Reflection Absorpthion Spectroscopy (PEM-IRRAS) and Quartz Crystal Microbalance (QCM) were employed to verify the adsorption of SWNTs on the gold electrodes.The results proved that SWNTs could enhance the direct electron transfer proecss between the electrodes and redox proteins.     

A New Anode for Lithium‐Ion Batteries Based on Single‐Walled Carbon Nanotubes and Graphene: Improved Performance through a Binary Network Design

Carbon nanomaterials, especially graphene and carbon nanotubes, are considered to be favorable alternatives to graphite‐based anodes in lithium‐ion batteries, owing to their high specific surface area, electrical conductivity, and excellent mechanical flexibility. However, the limited number of storage sites for lithium ions within the sp²‐carbon hexahedrons leads to the low storage capacity. Thus, rational structure design is essential for the preparation of high‐performance carbon‐based anode materials. Herein, we employed flexible single‐walled carbon nanotubes (SWCNTs) with ultrahigh electrical conductivity as a wrapper for 3D graphene foam (GF) by using a facile dip‐coating process to form a binary network structure. This structure, which offered high electrical conductivity, enlarged the electrode/electrolyte contact area, shortened the electron‐/ion‐transport pathways, and allowed for efficient utilization of the active material, which led to improved electrochemical performance. When used as an anode in lithium‐ion batteries, the SWCNT‐GF electrode delivered a specific capacity of 953 mA h g^?1 at a current density of 0.1 A g^?1 and a high reversible capacity of 606 mA h g^?1 after 1000 cycles, with a capacity retention of 90 % over 1000 cycles at 1 A g^?1 and 189 mA h g^?1 after 2200 cycles at 5 A g^?1.     

Covalent Attachment of Anderson‐Type Polyoxometalates to Single‐Walled Carbon Nanotubes Gives Enhanced Performance Electrodes for Lithium Ion Batteries

Single‐walled carbon nanotubes (SWNTs) covalently functionalized with redox‐active organo‐modified polyoxometalate (POM) clusters have been synthesized and employed as electrode materials in lithium ion batteries. The Anderson cluster [MnMo₆O₂₄]^9? is functionalized with Tris (NH₂C(CH₂OH)₃) moieties, giving the new organic–inorganic hybrid [N(nC₄H₉)₄]₃[MnMo₆O₁₈{(OCH₂)₃CNH₂}₂]. The compound is then covalently attached to carboxylic acid‐functionalized SWNTs by amide bond formation and the stability of this nanocomposite is confirmed by various spectroscopic methods. Electrochemical analyses show that the nanocomposite displays improved performance as an anode material in lithium ion batteries compared with the individual components, that is, SWNTs and/or Anderson clusters. High discharge capacities of up to 932 mAh g^?1 at a current density of 0.5 mA cm^?2 can be observed, together with high long‐term cycling stability and decreased electrochemical impedance. Chemisorption of the POM cluster on the SWNTs is shown to give better electrode performance than the purely physisorbed analogues.     

Heightened Integration of POM‐based Metal–Organic Frameworks with Functionalized Single‐Walled Carbon Nanotubes for Superior Energy Storage

To increase the conductivity of polyoxometalate‐based metal–organic frameworks (POMOFs) and promote their applications in the field of energy storage, herein, a simple approach was employed to improve their overall electrochemical performances by introducing a functionalized single‐walled carbon nanotubes (SWNT‐COOH). A new POMOF compound, [Cu₁₈(trz)₁₂Cl₃(H₂O)₂][PW₁₂O₄₀] (CuPW), was successfully synthesized, then the size‐matched functionalized SWNT–COOH was introduced to fabricate CuPW/SWNT–COOH composite (PMNT–COOH) by employing a simple sonication‐driven periodic functionalization strategy. When the PMNT–COOH nanocomposite was used as the anode material for Lithium‐ion batteries (LIBs), PMNT–COOH( 3 ) (CuPWNC:SWNT‐COOH=3:1) showed superior behavior of energy storage, a high reversible capacity of 885 mA h g^?1 up to a cycle life of 170 cycles. The electrochemical results indicate that the uniform packing of SWNT–COOH provided a favored contact between the electrolyte and the electrode, resulting in enhanced specific capacity during lithium insertion/extraction process. This fabrication of PMNT–COOH nanocomposite opens new avenues for the design and synthesis of new generation electrode materials for LIBs.     

A Bipolar and Self‐Polymerized Phthalocyanine Complex for Fast and Tunable Energy Storage in Dual‐Ion Batteries

Bipolar redox organics have attracted interest as electrode materials for energy storage owing to their flexibility, sustainability and environmental friendliness. However, an understanding of their application in all‐organic batteries, let alone dual‐ion batteries (DIBs), is in its infancy. Herein, we propose a strategy to screen a variety of phthalocyanine‐based bipolar organics. The self‐polymerizable bipolar Cu tetraaminephthalocyanine (CuTAPc) shows multifunctional applications in various energy storage systems, including lithium‐based DIBs using CuTAPc as the cathode material, graphite‐based DIBs using CuTAPc as the anode material and symmetric DIBs using CuTAPc as both the cathode and anode materials. Notably, in lithium‐based DIBs, the use of CuTAPc as the cathode material results in a high discharge capacity of 236 mAh g^?1 at 50 mA g^?1 and a high reversible capacity of 74.3 mAh g^?1 after 4000 cycles at 4 A g^?1. Most importantly, a high energy density of 239 Wh kg^?1 and power density of 11.5 kW kg^?1 can be obtained in all‐organic symmetric DIBs.     

Initial Electrode Kinetics of Anion Intercalation and De‐intercalation in Nonaqueous Al‐Graphite Batteries†

Graphitic materials with intercalated sites are considered as the mostly used positive electrode materials in nonaqueous Al batteries. Unlike the small‐size cations, the intercalation/de‐intercalation of large‐size anions into/out of graphite would induce large volume expansion and micro‐structure reconfiguration, leading to unexpected coulombic efficiency in the full cells (<95% within initial several cycles). For understanding the irreversible processes induced by anion intercalation/de‐intercalation (AlCl₄^–), here the kinetics of first two cycles for the Al‐graphite batteries have been systematically studied. To study kinetics behaviors at representative states, a combined method upon galvanostatic intermittent titration technique and electrochemical impedance spectroscopy has been carried out. The achieved diffusion coefficients of the positive electrodes assembled with different graphite sizes suggest that size effect also plays a critical role in determining the electrochemical kinetics in the mass transport in both electrolyte and graphitic layers as well as in interface reaction. The morphologies and micro‐structures of the post‐cycled graphite electrodes have been also experimentally studied, which also well supports the irreversible intercalation/de‐intercalation behaviors in graphite electrodes. The results offer a significant platform to well understand the essential factors in tailoring coulombic efficiency from a kinetic view, which would be helpful in promoting the graphite electrodes in Al batteries.     

Electrochemical Performance of Graphitic Multi-walled Carbon Nanotubes with Different Aspect Ratios as Cathode Materials for Aluminum-ion Batteries

Graphitic multi-walled carbon nanotubes (MWCNTs) can function as high-performance cathode materials for rechargeable Al-ion batteries with well-defined discharging plateaus and reasonable charge/discharge C-rates. However, the main intercalation/deintercalation or adsorption/desorption path of AlCl₄⁻ anions into or onto G-MWCNTs has not been elucidated. Herein, we used battery cells comprised of G-MWCNTs with different aspect ratios, Al metal, and AlCl₃/1-ethyl-3-methylimidazolium chloride ionic liquid as the cathode, anode, and electrolyte, respectively. The electrochemical performance of the Al||G-MWCNT cell increased as the aspect ratio of the G-MWCNT cathode increased (i. e., longer and thinner). The degree of defects of the G-MWCNTs was similar (0.15–0.22); hence, the results confirm that the main and alternate paths for the AlCl₄⁻ intercalation/de-intercalation or adsorption/desorption into/from or onto/from the G-MWCNT are the basal and edge planes, respectively. The step-like structures of defects on the basal plane provide the main reaction site for AlCl₄⁻ anions.     

Transformation of Rusty Stainless‐Steel Meshes into Stable,Low‐Cost,and Binder‐Free Cathodes for High‐Performance Potassium‐Ion Batteries

To recycle rusty stainless‐steel meshes (RSSM) and meet the urgent requirement of developing high‐performance cathodes for potassium‐ion batteries (KIB), we demonstrate a new strategy to fabricate flexible binder‐free KIB electrodes via transformation of the corrosion layer of RSSM into compact stack‐layers of Prussian blue (PB) nanocubes (PB@SSM). When further coated with reduced graphite oxide (RGO) to enhance electric conductivity and structural stability, the low‐cost, stable, and binder‐free RGO@PB@SSM cathode exhibits excellent electrochemical performances for KIB, including high capacity (96.8 mAh g⁻¹), high discharge voltage (3.3 V), high rate capability (1000 mA g⁻¹; 42 % capacity retention), and outstanding cycle stability (305 cycles; 75.1 % capacity retention).     

Direct Electrochemistry of Catalase at a Gold Electrode Modified with Single‐Wall Carbon Nanotubes

The direct electrochemistry of catalase (Ct) was accomplished at a gold electrode modified with single‐wall carbon nanotubes (SWNTs). A pair of well‐defined redox peaks was obtained for Ct with the reduction peak potential at ?0.414 V and a peak potential separation of 32 mV at pH 5.9. Both reflectance FT‐IR spectra and the dependence of the reduction peak current on the scan rate revealed that Ct adsorbed onto the SWNT surfaces. The redox wave corresponds to the Fe(III)/Fe(II) redox center of the heme group of the Ct adsorbate. Compared to other types of carbonaceous electrode materials (e.g., graphite and carbon soot), the electron transfer rate of Ct redox reaction was greatly enhanced at the SWNT‐modified electrode. The peak current was found to increase linearly with the Ct concentration in the range of 8×10^?6–8×10^?5 M used for the electrode preparation and the peak potential was shown to be pH dependent. The catalytic activity of Ct adsorbates at the SWNTs appears to be retained, as the addition of H₂O₂ produced a characteristic catalytic redox wave. This work demonstrates that direct electrochemistry of redox‐active biomacromolecules such as metalloenzymes can be improved through the use of carbon nanotubes.     

Amorphous MnO2 as Cathode Material for Sodium‐ion Batteries

Amorphous MnO₂ has been prepared from the reduction of KMnO₄ in ethanol media by a facile one‐step wet chemical route at room temperature. The electrochemical properties of amorphous MnO₂ as cathode material in sodium‐ion batteries (SIBs ) are studied by galvanostatic charge/discharge testing. And the structure and morphologies of amorphous MnO₂ are investigated by X‐ray diffraction (XRD ), scanning electron microscopy (SEM ), transmission electron microscopy (TEM ) and Raman spectra. The results reveal that as‐synthesized amorphous MnO₂ electrode material exhibits a spherical morphology with a diameter between 20 and 60 nm. The first specific discharge capacity of the amorphous MnO₂ electrode is 123.2 mAh •g⁻¹ and remains 136.8 mAh •g⁻¹ after 100 cycles at the current rate of 0.1 C. The specific discharge capacity of amorphous MnO₂ is maintained at 139.2, 120.4, 89, 68 and 47 mAh •g⁻¹ at the current rate of 0.1 C, 0.2 C, 0.5 C, 1 C and 2 C, respectively. The results indicate that amorphous MnO₂ has great potential as a promising cathode material for SIBs .     

Facile Synthesis of Nitrogen‐Containing Mesoporous Carbon for High‐Performance Energy Storage Applications

Porous carbon with high specific surface area (SSA), a reasonable pore size distribution, and modified surface chemistry is highly desirable for application in energy storage devices. Herein, we report the synthesis of nitrogen‐containing mesoporous carbon with high SSA (1390 m² g^?1), a suitable pore size distribution (1.5–8.1 nm), and a nitrogen content of 4.7 wt % through a facile one‐step self‐assembly process. Owing to its unique physical characteristics and nitrogen doping, this material demonstrates great promise for application in both supercapacitors and encapsulating sulfur as a superior cathode material for lithium–sulfur batteries. When deployed as a supercapacitor electrode, it exhibited a high specific capacitance of 238.4 F g^?1 at 1 A g^?1 and an excellent rate capability (180 F g^?1, 10 A g^?1). Furthermore, when an NMC/S electrode was evaluated as the cathode material for lithium–sulfur batteries, it showed a high initial discharge capacity of 1143.6 mA h g^?1 at 837.5 mA g^?1 and an extraordinary cycling stability with 70.3 % capacity retention after 100 cycles.     

Revisiting Surface Modification of Graphite: Dual‐Layer Coating for High‐Performance Lithium Battery Anode Materials

Surface modification of electrode active materials has garnered considerable attention as a facile way to meet stringent requirements of advanced lithium‐ion batteries. Here, we demonstrated a new coating strategy based on dual layers comprising antimony‐doped tin oxide (ATO) nanoparticles and carbon. The ATO nanoparticles are synthesized via a hydrothermal method and act as electronically conductive/electrochemically active materials. The as‐synthesized ATO nanoparticles are introduced on natural graphite along with citric acid used as a carbon precursor. After carbonization, the carbon/ATO‐decorated natural graphite (c/ATO‐NG) is produced. In the (carbon/ATO) dual‐layer coating, the ATO nanoparticles coupled with the carbon layer exhibit unprecedented synergistic effects. The resultant c/ATO‐NG anode materials display significant improvements in capacity (530 mA h g^?1), cycling retention (capacity retention of 98.1 % after 50 cycles at a rate of C/5), and low electrode swelling (volume expansion of 38 % after 100 cycles) which outperform that of typical graphite materials. Furthermore, a full‐cell consisting of a c/ATO‐NG anode and an LiNi_0.5Mn_1.5O₄ cathode presents excellent cycle retention (capacity retention of >80 % after 100 cycles). We envision that the dual‐layer coating concept proposed herein opens a new route toward high‐performance anode materials for lithium‐ion batteries.     

Spectroscopic Characteristics of Differently Produced Single‐Walled Carbon Nanotubes

Single‐walled carbon nanotubes (SWNTs) synthesized with different methods are investigated by using multiple characterization techniques, including Raman scattering, optical absorption, and X‐ray absorption near edge structure, along with X‐ray photoemission by following the total valence bands and C 1s core‐level spectra. Four different SWNT materials (produced by arc discharge, HiPco, laser ablation, and CoMoCat methods) contain nanotubes with diameters ranging from 0.7 to 2.8 nm. The diameter distribution and the composition of metallic and semiconducting tubes of the SWNT materials are strongly affected by the synthesis method. Similar sp² hybridization of carbon in the oxygenated SWNT structure can be found, but different surface functionalities are introduced while the tubes are processed. All the SWNTs demonstrate stronger plasmon resonance excitations and lower electron binding energy than graphite and multiwalled carbon nanotubes. These SWNT materials also exhibit different valence‐band X‐ray photoemission features, which are considerably affected by the nanotube diameter distribution and metallic/semiconducting composition.     

Two-Dimensional SnSe2/CNTs Hybrid Nanostructures as Anode Materials for High-Performance Lithium-Ion Batteries

Tin diselenide (SnSe₂), as an anode material, has outstanding potential for use in advanced lithium-ion batteries. However, like other tin-based anodes, SnSe₂ suffers from poor cycle life and low rate capability due to large volume expansion during the repeated Li⁺ insertion/de-insertion process. This work reports an effective and easy strategy to combine SnSe₂ and carbon nanotubes (CNTs) to form a SnSe₂/CNTs hybrid nanostructure. The synthesized SnSe₂ has a regular hexagonal shape with a typical 2D nanostructure and the carbon nanotubes combine well with the SnSe₂ nanosheets. The hybrid nanostructure can significantly reduce the serious damage to electrodes that occurs during electrochemical cycling processes. Remarkably, the SnSe₂/CNTs electrode exhibits a high reversible specific capacity of 457.6 mA h g⁻¹ at 0.1 C and 210.3 mA h g⁻¹ after 100 cycles. At a cycling rate of 0.5 C, the SnSe₂/CNTs electrode can still achieve a high value of 176.5 mA h g⁻¹, whereas a value of 45.8 mA h g⁻¹ is achieved for the pure SnSe₂ electrode. The enhanced electrochemical performance of the SnSe₂/CNTs electrode demonstrates its great potential for use in lithium-ion batteries. Thus, this work reports a facile approach to the synthesis of SnSe₂/CNTs as a promising anode material for lithium-ion batteries.     

A Versatile Halide Ester Enabling Li‐Anode Stability and a High Rate Capability in Lithium–Oxygen Batteries

Li‐O₂ batteries are promising candidates for next‐generation high‐energy‐density battery systems. However, the main problems of Li–O₂ batteries include the poor rate capability of the cathode and the instability of the Li anode. Herein, an ester‐based liquid additive, 2,2,2‐trichloroethyl chloroformate, was introduced into the conventional electrolyte of a Li–O₂ battery. Versatile effects of this additive on the oxygen cathode and the Li metal anode became evident. The Li–O₂ battery showed an outstanding rate capability of 2005 mAh g^?1 with a remarkably decreased charge potential at a large current density of 1000 mA g^?1. The positive effect of the halide ester on the rate capacity is associated with the improved solubility of Li₂O₂ in the electrolyte and the increased diffusion rate of O₂. Furthermore, the ester promotes the formation of a solid–electrolyte interphase layer on the surface of the Li metal, which restrains the loss and volume change of the Li electrode during stripping and plating, thereby achieving a cycling stability over 900 h and a Li capacity utilization of up to 10 mAh cm^?2.     

A Pyrazine‐Based Polymer for Fast‐Charge Batteries

The lack of high‐power and stable cathodes prohibits the development of rechargeable metal (Na, Mg, Al) batteries. Herein, poly(hexaazatrinaphthalene) (PHATN), an environmentally benign, abundant and sustainable polymer, is employed as a universal cathode material for these batteries. In Na‐ion batteries (NIBs), PHATN delivers a reversible capacity of 220 mAh g^?1 at 50 mA g^?1, corresponding to the energy density of 440 Wh kg^?1, and still retains 100 mAh g^?1 at 10 Ag^?1 after 50 000 cycles, which is among the best performances in NIBs. Such an exceptional performance is also observed in more challenging Mg and Al batteries. PHATN retains reversible capacities of 110 mAh g^?1 after 200 cycles in Mg batteries and 92 mAh g^?1 after 100 cycles in Al batteries. DFT calculations, X‐ray photoelectron spectroscopy, Raman, and FTIR show that the electron‐deficient pyrazine sites in PHATN are the redox centers to reversibly react with metal ions.     

Sulfur‐Rich Phosphorus Sulfide Molecules for Use in Rechargeable Lithium Batteries

A new family of sulfur‐rich phosphorus sulfide molecules (P₄S_10+n ) and their electrochemical reaction mechanism with metallic Li has been explored. These P₄S_10+n molecules are synthesized by the reaction between P₄S₁₀ and S. For Li batteries, the P₄S₄₀ molecule in the series of P₄S_10+n molecules provides the highest capacity, which has a first discharge capacity of 1223 mAh g⁻¹ at 100 mA g⁻¹ and stabilizes at approximately 720 mAh g⁻¹ at 500 mA g⁻¹ after 100 cycles. This new class of sulfur‐rich P₄S_10+n molecules and its electrochemical behavior for room‐temperature Li⁺ storage could provide novel insights for phosphorus sulfide molecules and high‐energy batteries.