Excellent Electronic Conductivity Research Articles

Anti-perovskite nitrides as chemically stable lithiophilic materials for highly reversible Li plating/stripping

Constructing structured anodes with lithiophilic materials has emerged as an essential strategy to stabilize Li deposition and accomplish highly reversible Li metal batteries (LMBs). Nevertheless, a lithiophilic material, which meets the requirements of low cost, excellent electronic conductivity and especially chemical stability, is still absent. Herein, we report the discovery of a new class of lithiophilic anti-perovskite nitrides MNNi3 (M=Zn, Cu, In) that not only are cost-effective and highly conductive, but also possess excellent stability against Li metal. More specifically, electrochemical tests in combination with density functional theory (DFT) calculations reveal that the lithiophilicity of MNNi3 arises from unique chemical/physical adsorption rather than the previously proposed alloying or conversion reaction mechanisms. The MNNi3@CC enabled symmetric cells exhibit better rate capability and longer cycle life than the cells with pure carbon cloth and Ni3N@CC. More importantly, the excellent electrochemical performances of MNNi3 anodes are also verified by ZnNNi3@CC in a LiFePO4 coupled full cell with minimal capacity degradation of 28% in 1500 cycles under the charge/discharge current of 1C. Beyond offering a new type of non-reactive lithiophilic materials to outstanding achieve battery performance, this study deepens the understanding of the lithiophilic nature of different metal nitrides, which paves a way for developing highly reversible lithium metal anode.

Asymmetric pseudocapacitive electrodes for high energy density supercapacitor in aqueous electrolyte

An Asymmetric pseudocapacitor electrodes can achieve higher energy density than carbon-based materials. Ruthenium oxide is the most effective pseudocapacitor material, but it's very expensive and toxic. The use of cerium oxide (CeO2), which is abundant with good redox properties could be a sustainable alternative for positive electrode. However, CeO2's low electronic conductivity limits its performance. To overcome this an asymmetric supercapacitor cell (ASC) was constructed using CeO2 as the positive electrode and instead of carbon-based materials, MXene (Ti3C2Tx) was used as the negative electrode. MXene can deliver better capacitance due to the controllable layer spacing and excellent electronic conduction which can improve the overall conductivity of the ASC. CeO2//MXene asymmetric cell achieved 122.27 Fg-1 capacitance with 55.02 Wh Kg−1 energy density, and retained 99.36 % initial capacitance after 10,000 cycles at 20 Ag-1.

Carbon/copper oxide electrode materials with high atomic utilization constructed by in-situ induced growth strategy of nano metal-organic frameworks

Carbon/metal composites derived from metal-organic frameworks (MOFs) have attracted widespread attention due to their excellent electronic conductivity, adjustable porosity, and outstanding stability. However, traditional synthesis methods are limited by the dense stereo geometry and large crystal grain size of MOFs, resulting in many metals active sites are buried in the carbon matrix. While the common strategy involves incorporating additional dispersed media into material, this leads to a decrease in practical metal content. In this study, nanosized copper-metal-organic frameworks (Cu-MOFs) are in-situ grown on surface of carbon spheres by pre-anchoring copper ions, and the hybrid composite of porous carbon/copper oxide with high copper atom utilization rate is prepared through activation and pyrolysis methods. This strategy effectively addresses the issue of insufficient exposure of metal sites, and the obtained composite material exhibits high effective copper atom utilization rate, large specific surface area (2052.3 m2·g−1), diverse pore structure, outstanding specific capacity (1076.5F·g−1 at 0.5 A·g−1), and excellent cycle stability. Furthermore, this highly atom-economical universal method has positive significance in application fields of catalysis, energy storage, and adsorption.

CuInS2/Red Phosphorus Nanosheet Interleaved Heterostructures with Improved Interfacial Charge Transfer for Photoelectrochemical Aptasensing.

Accelerating the migration of interfacial carriers in heterojunctions is crucial for achieving highly sensitive photoelectrochemical (PEC) sensing. In this study, we developed three-dimensional (3D)/two-dimensional (2D) CuInS2/red phosphorus nanosheet (CuInS2/RP NS) n-n heterojunction functional materials with enhanced interfacial charge transfer capabilities for PEC sensing. The 3D CuInS2 serves as a conductive layer, providing excellent electronic conductivity and superior electron absorption and transport properties. In contrast, the ultrathin RP NS acts as a transport layer that enhances carrier mobility. The 3D/2D heterojunction ensures a large interface contact surface, shortening the carrier transport distance. A well-aligned band position generates a substantial built-in electric field, providing a significant driving force for efficient carrier separation and migration, thereby improving response sensitivity. A PEC aptamer sensor was constructed based on the synthesized heterostructure for ciprofloxacin detection. The detection limit of the CuInS2/RP NS aptamer sensor for ciprofloxacin is 2.03 × 10-15 mg·mL-1, with a linear range from 1.0 × 10-14 to 1.0 × 10-5 mg·mL-1. This work presents a strategy for enhancing the photoelectric response by modulating the interface structure of heterojunctions, thereby opening new prospects for the application of highly sensitive PEC sensors in antibiotic detection.

Ionic Pumping Effect at the Tailored Mesoporous Carbon Interface for an Extra-Stable Lithium Ion Battery at Low Temperatures.

Ion transportation at the interface significantly influences the electrochemical performance of the lithium ion battery, especially at high rates and low temperatures. Here, we develop a controlled self-assembly strategy for constructing a mesoporous carbon nanolayer with a uniform pore size and varied thicknesses on the two-dimensional monolayer MXene substrate. On the basis of the excellent electron conductivity of MXene, the mesoporous carbon layer is found with a voltage-driven ion accumulation effect, acting as an "ionic pump". The thicker mesoporous layer (∼2.28 nm) has the ability to accommodate a substantial quantity of ions, demonstrating enhanced ionic conductivity, remarkable cycling stability (192.8 mAh/g after 9400 cycles at 5.0 A/g), and outstanding rate capability at ambient and sub-zero temperatures (∼601 mAh/g at 0 °C and 0.05 A/g). This work provides valuable insights and guidance for the further development of high-performance electrode materials at high rates or low temperatures.

Construction of an Ohmic Contact Cathode by Two Metal Sulfides for efficient Capture and Catalysis of Polysulfide.

The slow reaction kinetics and severe shuttle effect of lithium polysulfide make Li-S battery electrochemical performance difficult to meet the demands of large electronic devices such as electric vehicles. Based on this, an electrocatalyst constructed by metal phase material (MoS2) and semiconductor phase material (SnS2) with ohmic contact is designed for inhibiting the dissolution of lithium polysulfide with improving the reaction kinetics. According to the density-functional theory calculations, it is found that the heterostructured samples with ohmic contacts can effectively reduce the reaction-free energy of lithium polysulfide to accelerate the sulfur redox reaction, in addition to the excellent electron conduction to reduce the overall activation energy. The metallic sulfide can add more sulfophilic sites to promote the capture of polysulfide. Thanks to the ohmic contact design, the carbon nanotube-MoS2-SnS2 achieved a specific capacity of 1437.2 mAhg-1 at 0.1 C current density and 805.5 mAhg-1 after 500 cycles at 1 C current density and is also tested as a pouch cell, which proves to be valuable for practical applications. This work provides a new idea for designing an advanced and efficient polysulfide catalyst based on ohmic contact.

Fast-Charging Carbon Fiber Structural Battery Electrodes Using an Organic Polymer Active Material

Structural batteries require electrodes with integrated energy storage and load-bearing properties. Adoption of structural batteries can lead to mass and volume savings in electrified transportation and aerospace applications by storing energy within the object’s structural elements. However, to date, active materials investigated in structural batteries exhibit poor rate capabilities at higher C-rates and even worse performance at lower temperatures due to diffusion limitations. Organic radical polymers are promising alternatives because they possess fast-charging properties and good cycling stability. In this work, we integrate an organic radical polymer with carbon fiber (CF) fabric, in which the polymer acts as the active cathode material and the CF fabric possesses excellent tensile strength, modulus and electronic conductivity. At 20 °C, the structural cathodes exhibited a reversible capacity of 67 mAh g−1 at 1C-rate and an 88% capacity retention at 25C-rate. Further, these structural electrodes retained more than 50% of their performance at −10 °C (vs 20 °C). These electrodes were further examined in a full cell containing a graphite-based anode, demonstrating a pathway for utilizing redox-active polymer-based active materials in structural and fast-charging organic batteries.

NiAl LDH nanosheets based on Ag nanoparticles-decoration and alkali etching strategies for high performance supercapacitors

Layered double hydroxides (LDHs) represent a category of two-dimensional layered intercalation materials, showing significant potential as electrode materials for the production of high-energy-density supercapacitors due to their tunable composition, ease of synthetic modification, and low cost. Here, we constructed alkali-etched NiAl LDH-OH nanosheets/Ag nanoparticles (NPs) composite material (Ag@NiAl LDH-OH) for high-performance supercapacitors through a simple solvent-thermal reaction. The alkali treatment is employed to selectively etch some Al3+ ions, generating cation vacancies as active sites for energy storage. Additionally, under the simultaneous influence of strong alkalis and vacancies, the interlayer spacing of LDHs expands, aiding in the promotion of interlayer ion mobility. Meanwhile, the decoration of silver nanoparticles ensures excellent electron conductivity in the NiAl-LDH-OH nanosheets, thereby facilitating improved utilization of the active substance and achieving outstanding rate performance. The Ag@NiAl LDH-OH electrode, when prepared, demonstrates a significant increase in specific capacitance, reaching 1790 F g−1 at a current density of 1 A g−1. This represents approximately 7 times the specific capacitance of the pristine NiAl LDH electrode, with a capacity retention of 79 % even under a high current density of 20 A g−1. Moreover, the assembled asymmetric supercapacitor (ASC) attains a maximum energy density of 138.25 Wh kg−1 at a power density of 700 W kg−1, maintaining 81 % of its initial specific capacitance after 20000 cycles. This research introduces novel pathways for advancing high-energy-density SCs.

High-performance positive electrode material of MXene/FeNi2S4 nanocomposite for flexible supercapacitor with large potential window

Developing heterostructured nanomaterials with abundant active sites and excellent electronic conductivity is essential to enhance the electrochemical activity of supercapacitors. Herein, MXene/FeNi2S4 composites, as a high-performance electrode material for the flexible supercapacitor, were fabricated using a simple probe sonication method. The formation of a 3D architecture can create abundant electrochemical active sites, promoting the charge transfer as well as the redox reactions. Accordingly, a supercapacitor electrode based on MXene/FeNi2S4 exhibited excellent electrochemical performances, with a high specific capacitance of 673 F/g at 1 A/g. When MXene/FeNi2S4 was used as the electrode material of an asymmetric supercapacitor, the device showed an outstanding specific capacitance of 141 F/g at 1 A/g in a large potential window of 1.8 V. Up to 90 % of this high specific capacitance was retained after 2000 charge–discharge cycles. Furthermore, the device displayed high values of both energy density (63.37 Wh/kg) and power density (900.98 W/kg). The device also exhibited stable electrochemical performances under high flex at the bending angle of 135°. The exceptional electrochemical performances of MXene/FeNi2S4 highlight its great potential as an excellent electrode material for the next generation of flexible energy storage devices.

Fabrication of a Molybdenum Dioxide/Multi-Walled Carbon Nanotubes Nanocomposite as an Anodic Modification Material for High-Performance Microbial Fuel Cells.

A nanocomposite of multi-walled carbon nanotubes (MWCNTs) decorated with molybdenum dioxide (MoO2) nanoparticles is fabricated through the reduction of phosphomolybdic acid hydrate on functionalized MWCNTs in a hydrogen-argon (10%) atmosphere in a tube furnace. The MoO2/MWCNTs composite is proposed as an anodic modification material for microbial fuel cells (MFCs). MWCNTs have outstanding physical and chemical peculiarities, with functionalized MWCNTs having substantially large electroactive areas. In addition, combined with the exceptional properties of MoO2 nanoparticles, the synergistic advantages of functionalized MWCNTs and MoO2 nanoparticles give a MoO2/MWCNTs anode a large electroactive area, excellent electronic conductivity, enhanced extracellular electron transfer capacity, and improved nutrient transfer capability. Finally, the power harvesting of an MFC with the MoO2/MWCNTs anode is improved, with the MFC showing long-term repeatability of voltage and current density outputs. This exploratory research advances the fundamental application of anodic modification to MFCs, simultaneously providing valuable guidance for the use of carbon-based transition metal oxide nanomaterials in high-performance MFCs.

MoS2-C superlattice cathodes for conductive additive-free sulfide electrolyte-based all-solid-state lithium batteries

Sulfide electrolytes play a crucial role in the pursuit of high-performance all-solid-state lithium batteries (ASSLBs). However, most sulfide electrolytes have intrinsic narrow electrochemical stability windows, and decomposition reactions are thermodynamically favorable, especially contact with conductive additive. These ongoing side reactions accelerate sulfide electrolytes degradation, posing a significant threat to the cycling stability of ASSLBs. Herein, we propose an effective approach to address this challenge by designing a MoS2-C superlattice structure. This architecture, characterized by a layer-by-layer inter-stacking of MoS2 nanosheets and carbon layers, endows it with excellent electronic conductivity and enhanced lithium diffusion kinetics. Leveraging this superlattice, ASSLBs incorporating MoS2-C superlattice as the cathode without conductive additive exhibit a substantial improvement in electrochemical performance, ultimately achieving a conductive additive-free ASSLB. Remarkably, the conductive additive-free ASSLBs based on the MoS2-C superlattice demonstrates outstanding stability, enduring 300 cycles with a capacity retention of 96.8 % at a 1 C rate. This enhancement can be attributed to the improved charge transfer kinetics of MoS2-C superlattice and the effective suppression of side reactions between the sulfide electrolyte and conductive additive. Our study presents a promising design strategy to achieve high-rate performance and tackle long-term challenges in the application of sulfide electrolytes-based ASSLBs.

Layer effects on MXenes electrode and it applied to silicon composite structures

Despite the very high capacity of Si (4200mAh g−1), the widespread application of Si anodes has been hampered by drastic volume changes (up to 300 %) during cycling, leading to electrical contact losses and thus a sharp drop in capacity as the cycle life is shortened. Here we present a class of layered MXene/Si electrodes, which consist of nano-Si embedded in the interlayers of MXene to form a coupling effect, which can inhibit the huge volume change of Si during cycling. Therefore, layered MXene/Si has a highly reversible capacity, much improved cycling performance and excellent mechanical properties. First-principles calculations reveal the excellent electronic conductivity and good diffusion ability of layered MXene/Si, confirming the rapid storage of Li ions. This study provides useful information for the development and production of anode materials with high energy density and good mechanical properties.

The influence of in-situ induced and MnO2 polymorph-dependent structural changes to the energy storage and mechanism of supercapacitors

Due to its economic, environmental, and theoretical advantages, manganese dioxide (MnO2) is a promising cathode material for supercapacitors. However, the commercial application of MnO2 still faces challenges such as low intrinsic conductivity, slow ion diffusion, and structural instability. In this study, four crystalline forms of MnO2 powder electrodes (α-, β-, γ-, and δ-MnO2) were prepared, and results showed that with a specific capacitance of 218.2 F∙g−1, δ-MnO2 exhibited the best electrochemical performance. This was primarily due to the fact that δ-MnO2 possesses a high specific surface area, rich oxygen vacancy, and fast electron-ion transfer speed. A self-supported electrode (δ-MnO2/NF) without binder addition was further prepared using an in-situ-induced technique. The results revealed that the specific capacitance of δ-MnO2/NF was as high as 809.4 F∙g−1 and that the capacity retention rate and coulombic efficiency after 5000 cycles were 92.8 % and 99.2 %, respectively, which were superior to those of δ-MnO2 (80.3 % and 93.5 %). In-situ induction not only amplifies the structural advantages of δ-MnO2 but also generates more electrochemical active sites due to the intense interaction between NF and δ-MnO2. In addition, ultrathin nanosheet arrays formed on the NF provide a three-dimensional conductive network for the transport of ions and electrons. Density functional theory calculations were performed to verify the excellent electronic conductivity and ion diffusivity of δ-MnO2 and showed that transferring electrons from metal Ni to δ-MnO2 is the basis for producing numerous oxygen vacancies in δ-MnO2/NF.

Bimetallic Intercalated Vanadium Oxide As a High-Performance Cathode for Aqueous Zinc Ion Batteries.

In this paper, a bimetallic Na0.13Mg0.02V2O5·0.98H2O (NMVO) material with an interlayer spacing of 11.67 Å was synthesized by a simple preintercalation method as a cathode for zinc ionic batteries (ZIBs). The large layer spacing provides a wide channel for the embedding of Zn2+, resulting in high reversible capacity and ion diffusion kinetics. In addition, by virtue of the high electronic conductivity of metal ions, NMVO exhibits excellent electronic conductivity under the combined action of Na+ and Mg2+ bimetallic intercalation. At the same time, preintercalation ions and structural water act as interlayer pillars to stabilize the layer structure of NMVO during the cycling process. The above reasonable structural design endows the NMVO with excellent electrochemical performance. The battery with NMVO cathode delivers a high initial capacity of 126 mAh g-1 at 10 A g-1, and still remains at 76% after 5000 cycles, providing 100 Wh kg-1 energy density and 9.5 kW kg-1 power density (based on the mass of cathode). This bimetallic intercalation structure provides a general feasible scheme for the design of vanadium-based electrode materials.

Porous carbon prepared by thermal dissolution of coal and biomass for high-performance supercapacitors

Porous carbon materials have been considered a kind of promising materials for supercapacitors due to high specific surface area and excellent electronic conductivity. Soluble portions (SPs) acquired from thermal dissolution of carbon-based raw materials have been used as the carbon source for hierarchical porous carbons (HPC). In this work, mixtures of rice straw and coal at different mass ratios were selected as the raw materials for co-thermal dissolution to obtain SPX. The variation of soluble proportions and subsequent impacts on the electrochemical properties of HPCX were investigated. During thermal dissolution, the addition of rice straw increased the content of nitrogen-containing compounds in SPX. Therefore, the specific capacitance of HPC1/4 is 355 F/g. The specific capacitance of activated carbon material without rice straw is only 299 F/g. The relationship between the molecular characteristics of carbon source and the performance of supercapacitors has been determined. In addition to oxygen-containing compounds, the presence of nitrogen-containing compounds can also lead to a higher electrochemical property for porous carbon materials.

Supercapacitive performance of 3D-cobalt oxide (Co3O4) nanowires grown onto anodized stainless-steel substrate: Effect of anodization time

3D-Co3O4 nanowires were grown on anodized stainless steel (SSA) using a simple hydrothermal technique, with SSA as a cost-effective porous substrate. The originality of this work is to enhance surface activity and material adhesion by anodizing stainless steel (SS). After growth, the nanowires were thermally treated at 400 °C for 2 h. By varying the SS anodization time from 0 to 900s, changes in the structural, morphological, and electrochemical properties of Co3O4 were observed. XRD analysis confirmed the polycrystalline nature of Co3O4 with a face-centered cubic phase. SEM imaging showed noticeable changes in density and surface roughness. Supercapacitive properties were evaluated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) techniques, with SSANWs-300 exhibiting the highest specific capacitance of 529 Fg-1. Dunn's method was used to analyze the contribution of capacitive and diffusive mechanisms to charge storage. EIS results indicated excellent electronic conductivity. The study suggests that SSANWs-300 holds promise for energy storage applications.

One-Stone-for-Two-Birds Strategy for VSe2 to Enable High Capacity and Long-Life Zinc Storage.

Based on a specific zinc storage mechanism and excellent electronic conductivity, transition metal dichalcogenides, represented by vanadium diselenide, are widely used in aqueous zinc-ion battery (AZIB) energy storage systems. However, most vanadium diselenide cathode materials are presently limited by low specific capacity and poor cycling life. Herein, a simple hydrothermal process has been proposed for obtaining a vanadium diselenide cathode for an AZIB. The interaction of defects and crystal planes enhances zinc storage capacity and reduces the migration energy barrier. Moreover, abundant lamellar structure greatly increases reaction sites and alleviates volume expansion during the electrochemical process. Thus, the as-obtained vanadium diselenide AZIB exhibits an excellent reversible specific capacity of 377 mAh g-1 at 1 A g-1, and ultralong cycle stability of 291 mAh g-1 after 3200 cycles, with a nearly negligible capacity loss. This one-stone-for-two-birds strategy would be expected to be applied to large-scale synthesis of a high-performance zinc-ion battery cathode in the future.

A bifunctional strategy enabling 4.55 V LiCoO2 with improved electrochemical performance

LiCoO2 (LCO) has been functionally modified with electronic conductor of Al doped ZnO (AZO) and ionic conductor of Li3PO4 (LPO). The physicochemical characterization results demonstrated that the hexagonal structured AZO small crystal particles epitaxial growth formed island-like structures on the surface of LCO particles and LPO filled on the surface of remaining exposed LCO particles. Due to the unique composite coating layer with excellent electronic conductivity and Li ion conductivity, the AZO and LPO coated LCO exhibits outstanding rate capability and cycle stability in the voltage range of 2.75–4.55 V. The modified LCO delivered a specific capacity 206 mA h g−1 at 0.5C rate (100 mA g−1), and the capacity retention was 91.7 % after 50 cycles, which was a remarkable improvement comparing with uncoated LCO (34.8 %). Moreover, it exhibited an outstanding rate property, maintaining a discharge capacity of 161.4 mA h g−1 at 4C. This bifunctional strategy with AZO and Li3PO4 is an efficient approach to improve the electrochemical performance of LCO at high cut-off voltage (>4.5 V).

Subacute exposure to black phosphorus quantum dots induces cardiac fibrosis and the potential role of gut microbiota

Black phosphorus quantum dots (BPQDs) have been used as the nano-carrier in the field of biomedicine due to their excellent electronic conductivity, optical and thermoelectric properties. However, it is still lack of evaluation of the safety of BPQDs, specifically on the effects and mechanisms of BPQDs on heart. In this study, the specific pathogen-free male mice were orally administered with different doses of BPQDs (0.02, 0.1, 0.5 mg/kg) for 28 days. BPQDs exposure decreased the heart-body ratio and caused cardiac hypertrophy and fibrosis. Additionally, ferroptosis was observed in the cardiac tissue. The recent study has shown BPQDs oral exposure alter gut microbiota. Here, after exposure to 0.1 mg/kg BPQDs for 28 days, the germ-free mice showed neither cardiac injury nor ferroptosis. Taken together, the study demonstrates that BPQDs induce cardiac ferroptosis and fibrosis, possibly mediated by gut microbiota. This research may aid in enhancing understanding of the biosafety of BP nanomaterials and promoting the sustainable development of nanotechnology.

Uncovering the discharge structure evolution and electrochemical performance of sulfur cathode host 2D-Fe0.89M0.11S2 (M = Ti, V)

The sulfur cathode host materials with excellent electronic conductivity and catalytic performance are the key to highly efficient Li-S redox chemistry for the lithium‑sulfur batteries (LSBs). Although 2D-FeS2 as sulfur cathode host shows high theoretical capacity and flat voltage plateaus, the Li-S redox chemical reaction mechanism is still unclear. By using the first-principles calculations, the formation energy, working voltage, theoretical capacity, electronic conductivity, adsorption performance, electrocatalytic mechanism, Li+ diffusion and Li2S decomposition barrier of 2D-FeS2 and M (M = Ti, V) doped 2D-FeS2 are investigated to evaluate its physicochemical properties. 2D-Fe0.89M0.11S2 is thermodynamically stable due to its low lattice distortion, formation energy and mixing enthalpy. The charging voltage of 2D-Fe0.89Ti0.11S2 is better than that of 2D-Fe0.89V0.11S2, but the charging voltage step is reversed. The electrical conductivity of 2D-Fe0.89M0.11S2 is superior to 2D-FeS2. The closer the highest molecule occupied orbitals is to the Fermi level, the lower the discharge voltage will be. 2D-Fe0.89V0.11S2 and its discharge structure 2D-Li2Fe0.89V0.11S2 improve the efficiency of catalytic reduction of Li2S4. 2D-Fe0.89V0.11S2 has low Li+ diffusion and decomposition barrier of Li2S, which has potential application value in promoting the Li-S redox chemistry. This work deepens the understanding of the doping strategy and provides theoretical guidance for the design and development of sulfur cathode host to improve the Li-S redox chemistry.