Low Conductivity Research Articles

Regulating V2O5 Layer Spacing by a Polyaniline Molecule Chain to Improve Electrochemical Performance in Salinity Gradient Energy Conversion.

Salinity gradient energy is a chemical potential energy between two solutions with different ionic concentrations, which is also an ocean energy at the junction of rivers and seas. In our original work, the device "activated carbon//(0.083 M Na2SO4, 0.5 M Na2SO4)//vanadium pentoxide" for the conversion of salinity gradient energy was designed, and the conversion value of 6.29 J g-1 was obtained. However, the low specific surface area of the original V2O5 inevitably resulted in limited active sites and slow ionic transport rates, and the inherent lower conductivity and narrower layer spacing of the original V2O5 also resulted in poor electrode kinetic performance and cycle stability, hindering its practical application. To solve the above problems, the present work provides a strategy of using polyaniline (PANI) molecule chain intercalation to regulate the layer spacing of the original V2O5, and through the expansion and traction of the layer spacing, the composite PANI/V2O5 (PVO) with high specific surface area is prepared and used as an anode material for electrochemical conversion of salinity gradient energy application. The significantly increased layer spacing of the crystal plane (001) corresponding to the original V2O5 was confirmed with the PANI by the hydrogen bonding and the van der Waals force. The high specific surface area of the composite provides more electrochemical active sites to realize a fast Na+ migration rate and high specific capacitance. Meanwhile, the inserted PANI molecule chain, which acts not only as a pillar enlarging the Na+ diffusion channel but also as an anchor locking the gap between V2O5 bilayers, improves the structural stability of the V2O5 electrode during the electrochemical conversion process. The proposed insertion strategy for the conductive polymer PANI has created a new way to improve the cycle stability performance of the salinity gradient energy conversion device.

Pr6O11 modification effectively enhancing sodium storage for Na3V2(PO4)3 batteries

Na3V2(PO4)3 (NVP) is one of the most promising cathode materials for sodium-ion batteries (SIBs) due to its robust three-dimensional framework, high tunability, and relatively high Na+ intercalation potentials. However, its utility is generally constrained by low conductivity, inefficient charge transfer, and subpar interface kinetics. This work presents an efficient and simple method to address these issues. We innovatively modified the NVP surface with Pr6O11 nanoparticles, a negative temperature coefficient (NTC) thermosensitive material, to enhance interface compatibility with electrolytes and improve conductivity. This modification significantly enhances the overall sodium-ion storage performance. Specifically, the optimized NVP-2 %Pr6O11 electrode exhibits excellent electrochemical properties with the aid of an optimized conductivity network compared to the unmodified NVP. Cycled at an 8C current density, the NVP-2 %Pr6O11 electrode achieves high specific capacities of 102.6 mAh·g−1 at 27 °C and 95.6 mAh·g−1 at 45 °C. After 1000 cycles, the capacity retention rates are 81.18 % and 78.97 %, respectively, significantly higher than the 20.59 % and 14.99 % of pure NVP. In coin full-battery testing, the NVP-2 %Pr6O11 electrode retains 89.76 % capacity after 500 cycles at 8C. In addition, the assembled The NVP-2 %Pr6O11//HC pouch full battery exhibits better sodium-ion storage and thermal safety performance compared to the NVP-SP//HC battery. This simple modification strategy provides an effective insight into the application of NVP electrodes in energy storage.

Elevated CO2 concentration enhances plant growth, photosynthesis, and ion homeostasis of soybean under salt-alkaline stress

Salt-alkaline stress adversely affects growth and productivity of soybean. In the event of global climate change, the effects of elevated CO2 concentration (eCO2) and salt-alkaline stress on soybean remain unclear. This study investigated the combined effects of elevated CO2 concentration (700 μmol·moL−1) and salt-alkaline stress on soybean growth, gas exchange, pigments profiles, antioxidative enzyme activities, osmolyte accumulation, Na+ and K+ contents, and genes involved in ion homeostasis. This study suggested that eCO2 improved plant physiological performance due to the greater net photosynthetic rate (+212.49 %) and water use efficiency (+92.86 %). Both salt-alkaline stress and eCO2 significantly increased catalase (CAT) activity in leaves and stems, significantly increased superoxide dismutase (SOD) activity in stems, and significantly increased peroxidase (POD) activity in whole plants of soybean. eCO2 significantly inhibited Na+ absorption as indicated by decreased Na+ contents in whole plants under salt-alkaline stress accompanied by lower relative electrical conductivity, thus reducing osmotic and ionic stress. eCO2 induced enhancement of expressions of gene encoding the ion transporter of GmHKT1;2, GmHKT1;5, GmHKT1;6, GmNHX5, and GmSOS1 in stems mediated Na+ and K+ transport, thus benefiting to keep ions homeostasis. These results suggest that eCO2 contributes to enhancing soybean tolerance to saline-alkaline stress.

Ce-doped NiCo-layered double hydroxide based self-supporting tremella-shaped nanoflower heterostructure as efficient electrocatalyst for the oxygen evolution reaction

NiCo-layered double hydroxide (NiCo-LDH) catalysts, which indicate a profound prospect of oxygen evolution reaction (OER) under alkaline conditions, are facing great challenges in terms of low electrical conductivity, restricted by poor conductivity, limited electrochemical reaction sites, and low-density of edge sites. The authors developed a simple and convenient in-situ one-pot self-assembly method. The Ce-doped defective NiCo-LDH hexagonal nanosheets and nitrogen-doped graphene fabricated the NiCoCe-LDH/RNF electrocatalyst on the nickel foam (NF) substrate, which demonstrated excellent OER activity under alkaline conditions, only needed 299 mV overvoltage to achieve 50 mA cm−2 current intensity, could last for 6 hours at 20 mA cm−2. The highly active OER benefited from the structural advantages of the novelty three-dimensional array structure. The novel geometric structure of tremella-shaped nanoflower integrated with curved nanosheets and curled edges loaded on NF provides more electrochemical reaction sites for intermediate coordination. The nitrogen-doped reduced graphene oxide accommodated better interaction between active materials and charge carriers, enhancing the conductivity and electron transfer performance of nanostructures. The effective synergistic between the heterostructures promoted the excellent OER electrocatalytic activity of NiFeCe-LDH/RNF nanocomposites. DFT calculations at the atomic level of pristine and Ce-doped NiCo-LDH exhibited that Ce-doping can reduce the Gibbs free energy of the potential-determining step and improve the catalytic activity of OER. This work has broadened the horizons for developing simple and highly available OER electrocatalysts.

Highly conductive V4C3T x MXene-enhanced polyvinyl alcohol hydrogel electrolytes for flexible all-solid-state supercapacitors.

Hydrogel electrolytes are an integral part of flexible solid-state supercapacitors. To further improve the low ionic conductivity, large interfacial resistance and poor cycling stability for hydrogel electrolytes, the V4C3T x MXene-enhanced polyvinyl alcohol hydrogel electrolyte was fabricated to enhance its mechanical and electrochemical performance. The high-conductivity V4C3T x MXene (16,465.3Sm-1) bonding transport network was embedded into the PVA-H2SO4 hydrogel electrolyte (PVA- H2SO4-V4C3T x MXene). Results indicate that compared to the pure PVA-H2SO4 hydrogel electrolyte (105.3mScm-1, 48.4%@2,800 cycles), the optimal PVA-H2SO4-V4C3T x MXene hydrogel electrolyte demonstrates high ionic conductivity (133.3mScm-1) and commendable long-cycle stability for the flexible solid-state supercapacitors (99.4%@5,500 cycles), as well as favorable mechanical flexibility and self-healing capability. Besides, the electrode of the flexible solid-state supercapacitor with the optimal PVA-H2SO4-V4C3T x MXene hydrogel as the solid-state electrolyte has a capacitance of 370Fg-1 with almost no degradation in capacitance even under bending from 0° to 180°. The corresponding energy density for flexible device is 4.6Whkg-1, which is twice for that of PVA-H2SO4 hydrogel as the solid-state electrolyte.

Nano-organic polymers with rich redox sites as anode materials for dual-ion batteries

Organic electrode materials (OEMs) are considered one of the potential electroactive materials used in rechargeable batteries due to their high availability, low price, and sustainability. Nevertheless, the high solubility of their organic small molecules and their low electrical conductivity limit their practical applications. In this study, porous nanorods organic conjugated polymer were successfully prepared by a solvothermal method using 1,4,5,8-naphthalenetetracarboxylic anhydride and azodicarbonamide as precursors for dual-ion battery anodes. The successful synthesis of polymer extends the π-conjugated structure, effectively reducing its solubility in organic electrolytes. Moreover, the azo group (NN) in the polymer was easily conjugated with the adjacent aromatic ring, increasing the utilization of the active site, thereby improving the conductivity of the material so that the polymer has a high discharge capacity (90.5 mAh g−1 at 2 C, up to 96 % capacity retention). Even with a high rate of 10 C, the polymer still exhibits excellent electrochemical performance (50.0 mAh g−1 at 270 cycles). Moreover, reaction kinetics tests show that the electrode material was based on a pseudocapacitive storage mechanism influenced by diffusion and double-layer control. Therefore, the design strategy of such a material paves the way for the application of dual-ion batteries.

Microsphere LiMn0.6Fe0.4PO4/C cathode with unique rod-like secondary architecture for high energy lithium ion batteries

LiMnxFe1-xPO4/C is considered a promising next-generation cathode material with significant commercial potential, inheriting the safety of LiFePO4 while offering higher energy densities. However, the extremely low conductivity and the Jahn-Teller effect induced by Mn3+ limit its practical capacity and rate performance. Effective modifications can be achieved through particle nanonization and uniform carbon coating. Here, we synthesized microspherical LiMn0.6Fe0.4PO4/C cathode materials using a hydrothermal method combined with spray drying carbon coating. The cathode material exhibits a microsphere structure composed of aggregated nanorods with a uniform 3 nm carbon coating, showing good dispersibility, small specific surface area and high tap density. In-situ diffraction analysis showed that expanding the single-phase solid solution region during (de)lithiation can reduce the energy barrier for electron transport, improve the kinetics of the (dis)charge process, and enhance both cycling and rate performance. The initial capacity at 0.1C can reach 155 mAh/g, and the capacity remains at 133.5 mAh/g with a retention rate of 97.1 % after 300 cycles. The synergistic effect of particle nanonization and uniform carbon coating endows the LiMnxFe1-xPO4/C material with excellent electrochemical performance.

An Effective Strategy on Synthesizing a Stable SiOx-Based Anode for High Density Lithium-Ion Batteries.

Silicon oxides (SiOx) have received extensive attention as a promising anode candidate for next-generation lithium-ion batteries (LIBs). However, their commercial applications have been seriously hindered by low conductivity, large volume expansion, and unstable solid-electrolyte interface (SEI) layer, which result in low initial coulombic efficiency, poor rate performance, and short cycling lifespan. In this work, we demonstrated a simple way to prepare a series of SiOx materials with lithium fluoride (LiF) modified. When the mass ratio of SiOx and LiF equaled 1 : 0.15, the long-term cycling capacity retention could be greatly improved from 30.1 % to 76.5 % after 300 cycles. The result was primarily because of the enhancement of electrons and Li+-ions transport and the stability of the SEI layer due to LiF addition. However, excess LiF addition could hinder the diffusion of Li+-ions. This study presented the great potential of LiF modified on SiOx anode materials for LIBs.

Boosting Fast Charging of Lithium-Metal Batteries via Weak Interactions Between Non-Solvating Solvents and Anions in High-Safety Eutectic Electrolytes.

Proper design of the solvation structure is crucial for the development of lithium metal batteries (LMBs). In this paper, the use of 1,2-Dimethoxyethane (DME) as a non-solvating cosolvent in amide-based eutectic electrolytes is proposed to address challenges related to high viscosity, high polarization, and low conductivity, thus enhancing the compatibility with lithium metal anodes. Through physical characterization combined with simulation calculations the existence of a weak interaction between DME and anions is confirmed, which promotes the dissociation of lithium salts and increases the Li+ transference number and diffusion coefficient, thus improving the fast charging performance of eutectic electrolytes. In addition, stable SEI layer enriched with inorganic components is formed during the cycling process, resulting in uniform and dense lithium deposition. The fast charging performance of the cell can be effectively improved by utilizing the interaction between anions and solvents. The LiFePO4 (LFP)||Li cell has a capacity retention of 97% after 1200 cycles at 5 C and also performs well at high temperature of 50°C. Overall, the use of a non-solvating cosolvent in eutectic electrolytes presents a promising and innovative approach for enhancing electrolyte performance in LMBs.

Multiwalled carbon nanotubes decorated ɛ-MnO2 nanoflowers cathode with oxygen defect for aqueous zinc-ion batteries

As a potential cathode for aqueous zinc-ion batteries, the low electrical conductivity and poor electrochemical kinetics of MnO2 limit its further development and application. Herein, multiwalled carbon nanotubes decorated MnO2 nanoflowers with hexagonal structure (ɛ-MnO2/MWCNTs) were synthesized by one-step co-precipitation method. The ɛ-MnO2/MWCNTs inherit the advantages of highly conductive MWCNTs and nanostructured MnO2, thus showing excellent zinc-ion storage capacity. The ɛ-MnO2/MWCNTs display high invertible capacity of 335.6 mAh/g at 0.2 A/g after 150 cycles, and long-term capacity of 115.7 mAh/g at 2.0 A/g after 4000 cycles. The results of kinetics tests further reveal that the MWCNTs decoration can reduce polarization of MnO2 and accelerate its reaction kinetics. Thanks to these merits, the ɛ-MnO2/MWCNTs hold great potential for high performance eco-friendly batteries cathode material.

Wood-fiber insulation boards (WFIB) produced with hardwood and softwoods species and polylactic acid (PLA) fibers as a binder

ABSTRACT Wood fiber insulation boards (WFIB) produced with natural binders have been gaining recognition as an eco-friendly material, however there is limited information on the effect of different wood fiber and sustainable binders on WFIB production. This study investigates the impact of density, wood fiber origin, and pertinency of polylactic acid (PLA) as a binder. Flexible WFIB with densities of 80, 100 and 120 kg/m3 were produced by hot-press method with fibers of pine and spruce as softwoods, and beech and birch as hardwoods. Bicomponent fibers, composed by two concentrical layers of polylactic acid (PLA) were utilized as a renewable-origin binder at a proportion of 10%. Technological properties such as short-term water absorption, compression test and thermal tests properties were assessed. The density of the WFIB significantly influences the water absorption, compression strength, and thermal conductivity, with all these values increasing as the density rises. Insulation boards made from hardwood fibers showed greater water absorption and compression values compared than their softwood counterparts. Softwood-WFIB single-samples with a density of 80 kg/m3 reported lower thermal conductivities than hardwoods ones. The present study shows the promising feasibility of producing flexible wood fiber insulation boards from natural fibers and polylactic acid as a renewable binder.

Enhanced proton transfer in proton exchange membrane fuel cells via novel nanocomposite membrane incorporating (3-Mercaptopropyl)trimethoxysilane-graphene oxide and basic amino ligands: A synergistic acid-base approach

A nanocomposite polymer electrolyte membrane (MGC) was synthesized by blending MPTS (HS(CH2)3Si(OCH3)3) and graphene oxide (GO) nanosheets at varying weight ratios (91.5 to 9.5, respectively) for proton exchange membrane fuel cell (PEMFC) applications. By covalently modifying the GO support with MPTS through a silane modification process, the acidic MGC matrix is formed. The blending process, with ultrasonication and vigorous stirring, initiates two significant reactions in reactive MPTS: first, the conversion of methoxy groups (Si–OCH3) to silanols (Si-OH); second, the potential condensation of silanol groups to form siloxane bonds (Si–O–Si), followed by oxidation of sulfhydryl groups to sulfonic acid (-SO3H) groups by hydrogen peroxide. The resulting -SO3H groups connected to the siloxane network (Si-O-Si) adjacent to the GO. Two basic amino ligands – dopamine, and aminopropyl trimethoxysilane (APTES) were incorporated into the MGC matrix to establish acid-base pairs, promoting swift proton transport. These additions, at weight ratios of (0.5, 1, 2, and 7) wt%, synergistically contributed to the MGC matrix, forming effective proton channels. Various analytical techniques, including field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS), were employed to assess the impact of functionalized basic amino groups on the MGC matrix. Notably, the MGC membrane containing 2 wt% of PDA as basic amino ligands exhibited optimal performance, showcasing an in-plane proton conductivity of 115.10 mS cm-1 under fully hydrated conditions at 90 °C, and the maximum power density (MPD) of 170.74 mW cm-2 with a current density of 1051.46 mA cm-2 at 60 °C and 100 % relative humidity (RH). In contrast, the MGC membrane, devoid of amino ligands, exhibited a comparatively low in-plane conductivity of 44.32 mS cm⁻¹ under identical conditions at 90 °C. Additionally, it recorded the MPD of 48.5 mW cm⁻², corresponding to a current density of 313.25 mA cm⁻² at 60 °C and 100 % RH. This study introduces an innovative approach for developing high-performance nanocomposite membranes for PEMs and related applications.

Thermal conversion engineering of vanadium nitride-oxide cathode for high-rate aqueous Zn-ion battery

Vanadium-based materials are promising cathodes for high electrochemical performance aqueous Zn-ion batteries (AZIBs) due to their high specific capacity and multielectron redox reactions. However, vanadium-based materials suffer from low intrinsic conductivities and slow reaction kinetics, leading to poor rate performance. Here, we introduce vanadium nitride-oxide (VOVN) composites fabricated through a thermal conversion strategy, which exhibit high capacity and superior rate performance. The interface regulation of V2O3 and VN composite promotes charge carrier transport and enhances cathode reaction kinetics. Additionally, the dual energy storage mechanism in VOVN composites facilitates highly reversible Zn2+ storage processes. Consequently, the VOVN cathode demonstrates high discharge capacity (445.3 mAh g−1 at 0.1 A g−1), excellent rate performance (151.4 mAh g−1 at 30 A g−1), and fast diffusion coefficient (10−9–10−10 cm2 s−1). This study provides a straightforward and effective approach to developing high-performance cathodes for AZIBs.

Improved HER/OER Performance of NiS2/MoS2 Composite Modified by CeO2 and LDH.

In recent years, there has been significant interest in transition-metal sulfides (TMSs) due to their economic affordability and excellent catalytic activity. Nevertheless, it is difficult for TMSs to achieve satisfactory performance due to problems such as low conductivity, limited catalytic activity, and inadequate stability. Therefore, a catalyst with a heterostructure constituted of a nickel-iron-layered double hydroxide, nickel sulfide, molybdenum disulfide, and cerium dioxide was designed. At the current density of 10 mA cm-2 in an alkaline solution, the catalyst exhibits a HER overpotential of 116 mV. In addition, an overpotential of 235 mV@150 mA cm-2 was displayed for OER. The catalyst showed a good retention rate (94.7% for HER, 98.6% for OER) after 160 h stability tests. The excellent electrochemical performance is attributed to the following points: 1. The self-supporting three-dimensional hierarchical structure provides abundant sites, fast ion diffusion channels, and electron transfer paths, and ensures structural stability. 2. The strong interfacial electron interaction between Ni3S2/MoS2 heterojunction and NiFe-LDH improves the OER reaction kinetics. 3. The Ce3+ and oxygen vacancies in CeO2 promote the dissociation of H2O and promote the HER reaction kinetics. This approach paves the way for developing highly efficient electrocatalysts for various electrochemical applications.

Li-Ga Alloy-Contained Hybrid Solid Electrolyte Interphase Induced by In Situ Polymerization for High-Performance Lithium Metal Batteries.

Construction of quasi-solid-state lithium metal batteries (LMBs) by in situ polymerization is considered a key strategy for the next generation of energy storage systems with high specific energy and safety. Poly(1,3-dioxolane) (PDOL)-based electrolytes have attracted wide attention among researchers, benefiting from the low cost and high ionic conductivity. However, interfacial deterioration and uncontrollable growth of lithium dendrites easily appeared in LMBs due to the high reactivity of lithium metal, resulting in the failure of LMBs. In this work, a strategy is developed of using Ga(OTF)3 as the initiator to obtain a PDOL-based gel electrolyte (GaPD). In addition, a hybrid stable solid electrolyte interphase (SEI) of lithium fluoride/Li2O/Li-Ga alloys is observed on the surface of lithium metal. Combined with density functional theory calculations, the hybrid SEI shows high affinity toward Li+, indicating that a uniform deposition of Li+ could be achieved. Therefore, the Li/GaPD/Li cell operates stably for 1600 h at room temperature. In addition, the LiFePO4/GaPD/Li cell retains a capacity retention rate of 90.2% over 200 cycles at 1 C. This work provides a reference for the practical application of in situ polymerization technology in high-performance and safe LMBs.

Advances in Coating Materials for Silicon-Based Lithium-Ion Battery Anodes

Silicon anodes, which exhibit high theoretical capacity and very low operating potential, are promising as anode candidates that can satisfy the conditions currently required for secondary batteries. However, the low conductivity of silicon and the alloying/dealloying phenomena that occur during charging and discharging cause sizeable volume expansion with side reactions; moreover, various electrochemical issues result in inferior cycling performance. Therefore, many strategies have been proposed to mitigate these problems, with the most commonly used method being the use of nanosized silicon. However, this approach leads to another electrochemical limitation—that is, an increase in side reactions due to the large surface area. These problems can effectively be resolved using coating strategies. Therefore, to address the issues faced by silicon anodes in lithium-ion batteries, this review comprehensively discusses various coating materials and the related synthesis methods. In this review, the electrochemical properties of silicon-based anodes are outlined according to the application of various coating materials such as carbon, inorganic (including metal-, metal oxide-, and nitride-based) materials, and polymer. Additionally, double shells introduced using two materials for double coatings exhibit more complementary electrochemical properties than those of their single-layer counterparts. The strategy involving the application of a coating is expected to have a positive effect on the commercialization of silicon-based anodes.

α,ω-Alkanedibromides Form Low Conductance Chemisorbed Junctions with Silver Electrodes.

Chemical groups capable of connecting molecules physically and electrically between electrodes are of critical importance in molecular-scale electronics, influencing junction conductance, variability, and function. While the development of such linkage chemistries has focused on interactions at gold, the distinct reactivity and electronic structure of other electrode metals provides underexplored opportunities to characterize and exploit new binding motifs. In this work we show that α,ω-alkanedibromides spontaneously form well-defined junctions using silver, but not gold, electrodes through application of the glovebox-based scanning tunneling microscope-based break junction method. We systematically evaluate, through a series of additional studies, whether these molecular components form physisorbed or chemisorbed contact geometries, and if they undergo secondary chemical reactions at the silver surface. Critically, we find that the same junctions form when using different halide, or trimethylstannyl, terminal groups, suggestive of an electronically transparent silver-carbon(sp3) contact chemistry. However, the experimental conductance of the junctions we measure with silver electrodes is ∼30× lower than that observed for such junctions comprising gold-carbon(sp3) contacts, which does not align with predictions based on first-principles calculations. We further exclude the possibility that the proposed silver alkyl species undergo α- or β-hydride elimination reactions that result in a distinct contact chemistry through conductance measurements of control molecules that cannot undergo such processes. Applying insights provided from prior temperature-programmed desorption studies and a robust series of atomistic simulations, we ultimately propose that in these experiments we measure alkoxide-terminated junctions formed from the reaction of the chemisorbed alkyl with oxygen that is coadsorbed on the silver surface. This work, in demonstrating that high conductance contact chemistries established using model gold electrodes may not be readily transferred to other metals, underscores the need to directly characterize the interfacial electronic properties and reactivity of electrode metals of wider technological relevance.

Polyacrylonitrile and aluminum metal dual functionalization interconnected network for superior lithium storage in silicon anode

Currently, silicon-based anode is one of the most promising anode materials that can be applied in next-generation lithium-ion batteries. However, the high activity of the electrode–electrolyte interface and low electronic conductivity of Si anode during the cycling process greatly limits its large-scale application. Aluminum (Al) is the metallic current collector known to promote electronic conductivity and lithium-ion transfer at low cost. However, to our knowledge, scalable interface engineering incorporating Al with carbonized polymer has not been reported. Herein, a polyacrylonitrile (PAN) and aluminum metal dual functionalization interconnected network is achieved via a simple sol-gel method followed by high-temperature calcination to obtain a stable solid electrolyte interphase (SEI) while allowing fast Li+ transmission. The calculated diffusion energy barrier for lithium ions in Al is 0.2198 eV, significantly lower than that in Cu and Fe. Benefiting from the enhanced interfacial protection and kinetics of Si with polyacrylonitrile/Al, the prepared Si@Al@CPAN anode exhibits high lithium storage capacity (2034.90 mAh/g after 150 cycles at 0.84 A/g). At the same time, the prepared Si@Al@CPAN anode outperforms the pure Si anode in rate performance at 12.6 A/g (1116.75 mAh/g vs. 2.84 mAh/g). The present work delivers new design ideas for high-performance Si anode with a multi-functionalization interface.

A Porphyrin-Phenylalkynyl-Based Conjugated Organic Polymer as a High-Performance Cathode for Rechargeable Organic Batteries.

Organic electrode materials (OEMs) have attracted much attention for rechargeable batteries due to their low cost, environment friendliness, flexibility, and structural versatility. Despite the above advantages, high solubility in electrolyte and low electronic conductivity remain critical limitations for the application of OEMs. In this work, the conjugated organic polymer (COP) poly([5,10,15,20-tetrakis(4-phenylalkynyl)porphyrin]Cu(II)) (PCuTPEP) is proposed as a cathode for high performance in organic lithium batteries. The polymerization inhibits the dissolution of the organic electrodes in the electrolyte, and the porphyrin and ethynyl-phenyl groups greatly expand the conjugated system and result in a high average discharge plateau at 4.0 V (vs Li+/Li). The PCuTPEP cathode exhibits a reversible discharge capacity of 119 mAh g-1 at a current of 50 mA g-1. Even at a high current density of 2.0 A g-1, excellent cycling stability up to 1000 cycles is achieved with capacity retentions of 88.5 and 90.4% at operating temperatures of 25 and 50 °C in organic lithium batteries, respectively. This study provides the approach for the development of organic cathodes for electrochemical energy storage.

Electric Properties Change during Morphological Evolution of CeO2 Nanostructures: Synergy between Bulk and Surface Defects.

CeO2 samples were synthesized via the polymeric precursor method at different calcination temperatures. Electric properties were investigated using positron annihilation lifetime spectroscopy, electron paramagnetic resonance spectroscopy, and complex impedance spectroscopy. Reduction in the specific surface area of the particles with increasing calcination temperature along with morphological changes were observed. PALS depicted doubly ionized oxygen vacancies surrounded by two Ce3+ atoms, while the EPR spectroscopy showed a singly ionized oxygen vacancy surrounded by Ce3+ and Ce4+ ions. Impedance measurements unraveled the presence of polarons, while thermal treatments led to a lower electrical conductance, as the calcination temperature increased.