Intrinsic Electronic Conductivity Research Articles

Two-Dimensional Electrically Conductive Metal-Organic Framework Boosts Synaptic Plasticity for Dynamic Image Refresh, Classification, and Efferent Neuromuscular Systems.

We present a two-dimensional (2D) electrically conductive metal-organic framework (EC-MOF)-based artificial synapse. The intrinsic electronic conductivity and subnanometer channels of the EC-MOF facilitate efficient ion diffusion, enable a high density of active redox centers, and significantly enhance capacitance within the artificial synapse. As a result, the synapse operates at an ultralow voltage of 10 mV and exhibits a remarkably low power consumption of approximately 1 fW, along with the longest retention time recorded for two-terminal electrolyte-type artificial synapses to date. The alignment of the quantum size of the subnanometer pores in the EC-MOF with various cations allows for versatile synaptic plasticity. This capability is applied to image refresh, classification, and efferent signal transmission for controlling artificial muscles, thereby offering a methodology for achieving tunable neuromorphic properties. These findings suggest the potential application of metal-organic frameworks in artificial nervous systems for future brain-inspired computation, peripheral interfaces, and neurorobotics.

Molecular Engineering and Microstructure Modulation of High‐Performance Organic Batteries

Organic electrode materials (OEMs) featuring high abundance, structural designability, and eco‐friendliness, are considered promising candidates for rechargeable metal‐ion batteries. Nevertheless, the realization of efficient metal‐ion batteries based on OEMs is plagued by the poor intrinsic electronic conductivity and low insolubility of OEMs in common organic electrolytes. Herein, we present a systematic discussion of advancements in the design of OEMs from the perspective of molecular engineering and microstructure modulation, aiming at tuning the electrochemical, physical, and chemical properties of OEMs. Additionally, we elucidate the reaction mechanism of regulation strategies and provide new design directions for OEMs. This review offers essential concepts and perspectives on the development of advanced OEMs for rechargeable batteries.

Analyzing and Improving Conductive Networks in Commercial High‐Energy Ni‐rich Cathodes

AbstractNickel‐rich stoichiometries such as NMC811 have gained increasing relevance for lithium‐ion‐batteries in recent years due to their high specific capacity and reduced use of critical resources. However, low intrinsic electronic conductivity of NMC active materials makes the use of carbon‐based additives necessary. Volume fraction and distribution of the carbon‐binder‐domain (CBD) have a significant impact on the electrode performance. This work combines high‐resolution tomography and microstructure‐resolved simulations to characterize the three‐dimensional transport networks of a commercial NMC811 cathode. FIB‐SEM tomography reveals that low CBD volume fractions with suboptimal distribution cause a non‐percolating conductive network in the microstructure and thus unfavourably low electronic conductivity. Increasing the CBD content through virtual electrode design enables percolation and enhances electronic conductivity fundamentally. Simulations on both the real and virtually designed structures demonstrate how percolating CBD networks lead to a significantly improved energy density.

Design and Synthesis of Sb-Doped CuS@C Hollow Nanocubes as Efficient Anode Materials for Sodium-Ion Battery.

Copper sulfide has received widespread attention for application as anode materials in sodium-ion batteries due to their potent capabilitiess and eco-friendly properties. However, it is a challenge to achieve a high rate capability and long cycle stability owing to the heterogeneous transfer of sodium ions during charge-discharge, the interior poor electron conductivity and repeated volumetric expansion of copper sulfide. In this study, Sb-doped copper sulfide hollow nanocubes coated with carbon shells (Sb-CuS@C) was designed and constructed as anode nanomaterials in sodium-ion batteries. Thanks to the intrinsic good electron conductivity and chemical stability of carbon shells, Sb-CuS@C possesses a higher overall electron transfer as anode material, avoids agglomeration and structural destruction during the cycling. As a result, the synthesized Sb-CuS@C achieved an excellent reversible capacity of 595 mA h g-1 after 100 cycles at 0.5 A g-1 and a good rate capability of 340 mA h g-1 at a higher 10 A g-1. DFT calculations clarify that the uniformly doped Sb would act as active sodiophilic nucleation sites to help adsorbing sodium-ion during discharging and leading uniform sodium deposition. This work provides a new insight into the structural and componential modification for common transition-metal sulfides towards application as anode materials in sodium-ion battery.

Hierarchically Structured Conductive Lanthanide Metal Organic Framework Nanorods for Ultrastable Flexible Magnesium Ion Capacitors

AbstractAqueous multivalent metal ion capacitors are very attractive owing to their high capacitance, low cost, environmental benignity, and safety. Herein, hierarchically structured, conductive lanthanide metal‐organic frameworks (MOFs) assembled by nanorods for ultrastable flexible magnesium ion capacitors (MICs) is designed. Three MOFs, consisting of lanthanide metals (La, Ho, and Yb) and 2,3,6,7,10,11‐hexahydroxytriphenylene (HHTP), are structurally stabilized through the covalent bonds and electronically conductive due to π‐d conjugation. Among 3 MOFs, Ho‐HHTP electrodes in a full‐cell system achieved long‐term cyclic stability with a high capacitance retention of 65.0% after 12 000 cycles and a high Coulombic efficiency of 96.9%. Furthermore, flexible pouch cells are fabricated using Ho‐HHTP as anode, reduced graphene oxide as cathode, and poly(vinyl alcohol) (PVA)/Mg(ClO4)2 as gel electrolyte, demonstrating a low capacitance decay rate of 0.00444% per cycle during 10 000 cycles owing to the hierarchical structure and intrinsic electronic conductivity. As indicated by density functional theory and spectroscopic characterizations, Mg2+ ions are faradaically stored in the catechol part of the ligand, and Mg2+ inserted into the vacant Ho sites contributes to structural stability. Furthermore, operando 2D correlation Raman spectroscopy identified how Mg2+ ions interact with the ligand of Ho‐HHTP and demonstrated the sequential change of peak change.

Copper-induced lattice distortion in Na4Fe3(PO4)2(P2O7) cathode enabling high power density Na-ion batteries with good cycling stability

Na4Fe3(PO4)2P2O7 (NFPP) has attracted attention due to its high theoretical capacity, low cost, and good structure stability for Na-ion batteries. However, its practical application is limited by the low intrinsic electronic conductivity and sluggish ion diffusion kinetics. To tackle those problems, lattice strain engineering by heteroatom doping is applied to tune the local molecular structure and optimize the electrochemical properties of electrode materials. Copper cation (+2) with a smaller ionic radius was chosen to dope at Fe-site in NFPP, and the doping amount was also optimized, illustrating the optimized sample of Na4Fe2.7Cu0.3(PO4)2P2O7 (NFPP-0.3Cu) delivered a high capacity of 119.01 mAh g-1 at 1 C (1 C = 129 mA g-1) and a high capacity retention of 82.76 % after 3000 cycles at 20 C. Notably, full cells with NFPP-0.3 Cu as cathode and hard carbon as anode delivered a high energy density of 230 Wh kg-1 and a power density of 2280 W kg-1. The exceptional electrochemical performances are attributed to the modulated electronic structure and abundant lattice defects by Cu-doping. Furthermore, in-situ X-ray diffraction technique and theoretical calculation have jointly proved that the lattice distortions originated from Cu-doping have reduced the band gap of the NFPP-0.3Cu and altered the coordination environment of Fe, shortening the Fe-O and Cu-O bond lengths, significantly enhancing the intrinsic ionic conductivity and the diffusion kinetics of Na+. This work provides new point of views on lattice strain engineering and reaction kinetics of cathode materials in promoting high energy and power density sodium-ion batteries.

Local Electronic Structure Regulation Enabling Fluorophosphates Cathode with Improved Redox Potential and Reversible Capacity for Sodium-Ion Batteries.

Mn-based fluorophosphates have attracted much attention as cathodes for sodium-ion batteries owing to their high cost effectiveness, considerable capacity, and stable framework. However, the fascinating Mn3+/2+ redox couple suffers from inadequate activation due to the Mn-O covalent character and poor electronic conductivity, impeding its further applications. Herein, a local electronic structure regulation strategy is proposed to improve the Mn3+/2+ redox potential and reversible capacity simultaneously through introducing elements with low-energy 3d orbitals to expand the energy gap between the eg orbitals and Fermi energy of Na. Moreover, the 3d element substitution serves to narrow the band gap toward the improved intrinsic electronic conductivity. In comparison with pristine Na2Fe0.45Mn0.55PO4F, the as-prepared Na2Fe0.45Mn0.4V0.1PO4F cathode achieves an increase from 3.5 to 3.6 V in the high-voltage platform and an improvement in energy density from 330 to 361 Wh kg-1. This work inspires new ideas in adjusting the redox potential of polyanionic cathodes through deliberate regulation of the local electronic structure.

A Computation-Guided Design of Highly Defined and Dense Bimetallic Active Sites on a Two-Dimensional Conductive Metal-Organic Framework for Efficient H2O2 Electrosynthesis.

Electrochemical synthesis of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e--ORR) provides an alternative method to the energy-intensive anthraquinone method. Metal macrocycles with precise coordination are widely used for 2e--ORR electrocatalysis, but they have to be commonly loaded on conductive substrates, thus exposing a large number of 2e--ORR-inactive sites that result in poor H2O2 production rate and efficiency. Herein, guided by first-principle predictions, a substrate-free and two-dimensional conductive metal-organic framework (Ni-TCPP(Co)), composed of CoN4 sites in porphine(Co) centers and Ni2O8 nodes, is designed as a multi-site catalyst for H2O2 electrosynthesis. The approperiate distance between the CoN4 and Ni2O8 sites in Ni-TCPP(Co) weakens the electron transfer between them, thus ensuring their inherent activities and creating high-density active sites. Meanwhile, the intrinsic electronic conductivity and porosity of Ni-TCPP(Co) further facilitate rapid reaction kinetics. Therefore, outstanding 2e--ORR electrocatalytic performance has been achieved in both alkaline and neutral electrolytes (>90 %/85 % H2O2 selectivity within 0-0.8 V vs. RHE and >18.2/18.0 mol g-1 h-1 H2O2 yield under alkaline/neutral conditions), with confirmed feasibility for water purification and disinfection applications. This strategy thus provides a new avenue for designing catalysts with precise coordination and high-density active sites, promoting high-efficiency electrosynthesis of H2O2 and beyond.

A Computation‐Guided Design of Highly Defined and Dense Bimetallic Active Sites on a Two‐Dimensional Conductive Metal–Organic Framework for Efficient H2O2 Electrosynthesis

AbstractElectrochemical synthesis of hydrogen peroxide (H2O2) via the two‐electron oxygen reduction reaction (2e−‐ORR) provides an alternative method to the energy‐intensive anthraquinone method. Metal macrocycles with precise coordination are widely used for 2e−‐ORR electrocatalysis, but they have to be commonly loaded on conductive substrates, thus exposing a large number of 2e−‐ORR‐inactive sites that result in poor H2O2 production rate and efficiency. Herein, guided by first‐principle predictions, a substrate‐free and two‐dimensional conductive metal–organic framework (Ni‐TCPP(Co)), composed of CoN4 sites in porphine(Co) centers and Ni2O8 nodes, is designed as a multi‐site catalyst for H2O2 electrosynthesis. The approperiate distance between the CoN4 and Ni2O8 sites in Ni‐TCPP(Co) weakens the electron transfer between them, thus ensuring their inherent activities and creating high‐density active sites. Meanwhile, the intrinsic electronic conductivity and porosity of Ni‐TCPP(Co) further facilitate rapid reaction kinetics. Therefore, outstanding 2e−‐ORR electrocatalytic performance has been achieved in both alkaline and neutral electrolytes (>90 %/85 % H2O2 selectivity within 0–0.8 V vs. RHE and >18.2/18.0 mol g−1 h−1 H2O2 yield under alkaline/neutral conditions), with confirmed feasibility for water purification and disinfection applications. This strategy thus provides a new avenue for designing catalysts with precise coordination and high‐density active sites, promoting high‐efficiency electrosynthesis of H2O2 and beyond.

Cation/Anion Doping Strategy for Na4MnV(PO4)3 with High Energy Density and Long Cycling Life through Construction by Aspergillus niger.

Na4MnV(PO4)3 (NMVP) has gained attention for its high redox potential, good cycling stability, and competitive price but suffers from poor intrinsic electronic conductivity and Jahn-Teller effect from Mn3+. In this work, cation/anion doping strategy was used for Aspergillus niger-bioderived carbon-coated NMVP (NMVP/AN) to improve the structural stability and electrochemical performance, where Al3+ doping inhibited the dissolution of Mn and enhanced the Mn3+/Mn2+ redox pair activity; besides, F- doping not only weakens the Na2-O bond but also endows the hierarchical and porous structure of NMVP/AN, which led to a more rapid and fluid transfer of Na+. The elaborately designed Na3.9Mn0.9Al0.1V(PO4)3/AN (NMAVP/AN) exhibits 105.9 mA h g-1 at 0.5 C, and the as-prepared Na3.1MnV(PO3.7F0.3)3/AN (NMVPF/AN) delivers 104.1 mA h g-1 at 5 C. Further demonstration of the hard carbon//NMAVP/AN full cell manifests the good potential of Al3+-doped NMVP/AN for practical applications (100.6 mA h g-1 at 1 C). These findings open up the possibility of unlocking the high-performance Na superionic conductor (NASICON).

Identifying the β-to-α phase transition during the long cycling process in Na2FePO4F cathode

Na2FePO4F has emerged as a promising cathode for large-scale electrochemical energy storage, primarily due to its abundance of raw materials and distinctive two-dimensional ion channels. Counterintuitively, pristine Na2FePO4F lacks the long-term stability typically seen in polyanionic cathodes, which severely impedes its practical application. Traditionally, the origin of this problem has been only phenomenologically attributed to the poor intrinsic electronic conductivity and structural instability of Na2FePO4F. Here, we identify that rapid capacity fading of Na2FePO4F is closely related to the β-to-α phase transition during the long cycling process. Furthermore, we develop a practical high-entropy doping strategy and the corresponding microstructure engineering to mitigate the impact of the phase transition on the crystal structure, thereby increasing the capacity retention from 56 % to 94 % over 400 cycles at 0.5C in coin cell, and attain almost 100 % capacity retention after 300 cycles at 0.1C in pouch cell. Overall, this work unveils the mechanism of rapid capacity decay in Na2FePO4F and lays the groundwork for the rational design of durable polyanionic electrodes.

Co‐Based Metal–Organic Frameworks With Dual Redox Active Centers for Lithium‐Ion Batteries With High Capacity and Excellent Rate Capability

AbstractSmall molecule organic materials are widely used as anode materials for lithium‐ion batteries (LIBs) due to their high reversible capacity, designable structure, and environmental friendliness. However, they suffer from poor intrinsic electronic conductivity, severe dissolution, and low initial coulombic efficiency. Recently, metal–organic frameworks (MOFs) have demonstrated in metal‐ion batteries, outperforming some small molecule organic materials in terms of both cycling stability and rate capability. Herein, the first rational design and synthesis of a new cobalt‐based MOF (CoBPDCA), are reported employing cobalt(II) nitrate as the metal source and small organic molecules (2,2‐bipyridyl‐4,4‐dicarboxylic acid, BPDCA) as the ligands, which shows exceptional chemical stability and impressive electron conductivity. Most importantly, CoBPDCA electrodes deliver a high reversible capacity of 1112.9 mAh g−1 at 0.05 C (1 C = 1000 mA g−1) and outstanding high‐rate durability (166.3 mAh g−1 after 2500 cycles at 10 C). Employing a series of spectroscopic and morphological characterizations and density functional theory (DFT) calculations, it is revealed that these impressively electrochemical performances are contributed to the dual active redox centers of Co cations and BPDCA ligands (CN and CO groups), and the superb electron conductivity. This work might provide a new strategy and a deeper understanding of the other MOFs' development for LIBs.

Hollow Core-Shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with Tiny-Void Space Capable Fast-Charge and Low-Temperature Sodium Storage.

Iron-based mixed polyanion phosphate Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a promising cathode for Sodium-ion Batteries (SIBs) due to its low cost and environmental friendliness. However, its inherent low conductivity and sluggish Na+ diffusion limit fast charge and low-temperature sodium storage. This study pioneers a scalable synthesis of hollow core-shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with tiny-void space (THoCS-0.6Ni) via a one-step spray-drying combined with calcination process due to the different viscosity, coordination ability, molar ratios, and shrinkage rates between citric acid and polyvinylpyrrolidone. This unique structure with interconnected carbon networks ensures rapid electron transport and fast Na+ diffusion, as well as efficient space utilization for relieving volume expansion. Incorporating regulation of lattice structure by doping Ni heteroatom to effectively improve intrinsic electron conductivity and optimize Na+ diffusion path and energy barrier, which achieves fast charge and low-temperature sodium storage. As a result, THoCS-0.6Ni exhibits superior rate capability (86.4 mAh g-1 at 25 C). Notably, THoCS-0.6Ni demonstrates exceptional cycling stability at -20 °C with a capacity of 43.6 mAh g-1 after 2500 cycles at 5 C. This work provides a universal strategy to design the hollow core-shelled structure with tiny-void space cathode materials for reversible batteries with fast-charge and low-temperature Na-storage features.

Hollow Core‐Shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with Tiny‐Void Space Capable Fast‐Charge and Low‐Temperature Sodium Storage

AbstractIron‐based mixed polyanion phosphate Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a promising cathode for Sodium‐ion Batteries (SIBs) due to its low cost and environmental friendliness. However, its inherent low conductivity and sluggish Na+ diffusion limit fast charge and low‐temperature sodium storage. This study pioneers a scalable synthesis of hollow core–shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with tiny‐void space (THoCS‐0.6Ni) via a one‐step spray‐drying combined with calcination process due to the different viscosity, coordination ability, molar ratios, and shrinkage rates between citric acid and polyvinylpyrrolidone. This unique structure with interconnected carbon networks ensures rapid electron transport and fast Na+ diffusion, as well as efficient space utilization for relieving volume expansion. Incorporating regulation of lattice structure by doping Ni heteroatom to effectively improve intrinsic electron conductivity and optimize Na+ diffusion path and energy barrier, which achieves fast charge and low‐temperature sodium storage. As a result, THoCS‐0.6Ni exhibits superior rate capability (86.4 mAh g−1 at 25 C). Notably, THoCS‐0.6Ni demonstrates exceptional cycling stability at −20 °C with a capacity of 43.6 mAh g−1 after 2500 cycles at 5 C. This work provides a universal strategy to design the hollow core–shelled structure with tiny‐void space cathode materials for reversible batteries with fast‐charge and low‐temperature Na‐storage features.

Modification and Electrochemical Performance of Phenazine based Electrode Materials

Organic electrode materials hold great promise for advancing the development of aqueous batteries due to their structural diversity and sustainability. However, they still encounter challenges such as low electroactive mass contribution and undesirable cycling performance resulting from intrinsic poor electronic conductivity. Herein 1, 2-dihydroxyphenazine (DHP) was designed based on phenazine. Compared with the negative electrode of phenazine, the introduction of hydroxyl groups can reduce the redox potential by 0.2 V. The fast transport channel formed by intramolecular hydrogen bonding can significantly improve the redox kinetics. The optimized DHP‖Ni(OH)2 battery has a discharge capacity of 240 mAh/g and a high energy density over 50 Wh/kg.

Regulation on reacting solvent engineering for scalable synthesis of Na3(VOPO4)2F@carbon nanotubes microsphere cathodes towards high-power and long-lifespan Na-ion batteries

Na3(VOPO4)2F (NVOPF) has emerged as a promising cathode candidate for commercial Na-ion batteries, ascribed to its elevated theoretical energy density and robust structure during the extraction/insertion of two Na+ ions. However, the intrinsic poor electronic conductivity and unscalable materials-preparation technologies make it unexpected to stand out in large-scale energy storage systems. In this study, a spray-drying process technology is implemented to synthesize Na3(VOPO4)2F@carbon nanotubes (NVOPF@CNTs) composite through the reduction of V5+ driven by methanol at room temperature, in which the shortened Na-ion transfer path and the rapid electron mobility are facilitated by the CNTs. The resulting NVOPF@CNTs electrode exhibits exceptional capabilities, including a high discharge capacity (122.1 mA h g−1 at 1 C= 120 mA h g−1), outstanding rate performance (103.1 mA h g−1 at 100 C), and an extended lifespan (71.8 % capacity retention after 6000 cycles at 20 C). Additionally, the Na3(VOPO4)2F//NaTi2(PO4)3 full battery system demonstrates impressive high-power output capabilities (93.3 mA h g−1, 20 C), versatile current switching adaptability, and robust cycling performance (75.3 % of 98.5 mA h g−1 for the initial capacity after 3000 cycles). The study underscores the potential of improving the preparation of vanadium-based phosphate materials to enhance the practical application of Na-ion batteries.

Hexagonal MoO3 Anode with Extremely High Capacity and Cyclability for Lithium-Ion Battery: A Combined Theoretical and Experimental Study.

It is essential and still remains a big challenge to obtain fast-charge anodes with large capacities and long lifespans for Li-ion batteries (LIBs). Among all of the alternative materials, molybdenum trioxide shows the advantages of large theoretical specific capacity, distinct tunnel framework, and low cost. However, there are also some key shortcomings, such as fast capacity decaying due to structural instability during Li insertion and poor rate performance due to low intrinsic electron conductivity and ion diffusion capability, dying to be overcome. A unique strategy is proposed to prepare Ti-h-MoO3-x@TiO2 nanosheets by a one-step hydrothermal approach with NiTi alloy as a control reagent. The density functional theory (DFT) calculations indicate that the doping of Ti element can make the hexagonal h-MoO3-x material show the best electronic structure and it is favor to be synthesized. Furthermore, the hexagonal Ti-h-MoO3-x material has better lithium storage capacity and lithium diffusion capacity than the orthogonal α-MoO3 material, and its theoretical capacity is more than 50% higher than that of the orthogonal α-MoO3 material. Additionally, it is found that Ti-h-MoO3-x@TiO2 as an anode displays extremely high reversible discharge/charge capacities of 1326.8/1321.3 mAh g-1 at 1 A g-1 for 800 cycles and 611.2/606.6 mAh g-1 at 5 A g-1 for 2000 cycles. Thus, Ti-h-MoO3-x@TiO2 can be considered a high-power-density and high-energy-density anode material with excellent stability for LIBs.

Constructing interfacial chemical interaction of dual-carbon protected cobalt diselenide anode for sodium storage

Transition metal selenides are attracting enormous attention due to their high theoretical capacity and appropriate working potential for sodium storage, while their intrinsic low electronic conductivity and large volume expansion during the cycling processes inevitably result in inadequate rate performance and inferior cycling stability. Herein, cobalt diselenide-based hollow sugarloaf-like self-supporting fiber membranes with strong interfacial chemical (Co-C) bonds have been reported for sodium-ion batteries (SIBs) via the dual-carbon protection strategy. Based on X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) combined with density functional theory (DFT), A built-in electric field is generated at the interface between CoSe2/C and CNFs, which provides a strong driving force for electron transfer and ion migration, making the optimal CoSe2/C−0.3@CNFs anode over 67.8 % of capacity retention from 0.1 to 5 A/g and maintained about 269.5 mAh/g of discharge capacity at 5 A/g. The strong interfacial Co-C bonds in CoSe2/C@CNFs enhance the interfacial affinity between CoSe2/C and CNFs, making it easier for CoSe2/C to trap sodium ions and effectively resist the volume expansion during cycling, thus showing excellent cyclic stability with a reversible capacity of 247.6 mA h g−1 at 1.0 A/g after 2600 cycles. The sodium storage mechanism of CoSe2/C−0.3@CNFs electrode in SIBs is systematically analyzed via in-situ XRD and in-situ Raman spectra. This study provides an effective approach to constructing heterostructured composites with strong chemical bonds and built-in electric field characteristics for high-rate capability and long-cycle stability SIBs. Moreover, the sodium ion diffusion kinetics in the CoSe2/C−0.3@CNFs anode is also revealed.

Co-Assembly of Polyoxometalates and Porphyrins as Anode for High-Performance Lithium-Ion Batteries.

Polyoxometalates (POMs) have been considered one of the most promising anode candidates for lithium-ion batteries (LIBs) in virtue of their high theoretical capacity and reversible multielectron redox properties. However, the poor intrinsic electronic conductivity, low specific surface area, and high solubility in organic electrolytes hinder their widespread applications in LIBs. Herein, a novel hybrid nanomaterial is synthesized by co-assembling POMs and porphyrins (PMo12/CoTPyP) through a facile solvothermal method. The POM clusters are stabilized by porphyrin units through electrostatic interactions, which simultaneously realize the uniform dispersion of POMs and porphyrin units. Benefiting from the generated sub-1nm channels for fast ion transport and the synergistic effect between evenly distributed PMo12 clusters and high-conductive CoTPyP units, the LIB based on the optimized PMo12/CoTPyP anode exhibits significantly improved Li+ storage capability as well as superior rate and cycling performance. The results of density functional theory simulations further reveal that the co-assembly of PMo12 and CoTPyP can accelerate the mobility of Li+ and electrons, which in turn promotes the enhancement of LIBs performance. This work paves a strategy for synthesizing POMs-based anode materials with simultaneously high dispersibility, redox activity, and stability.

Polar organic molecules assisting Mo-based cathode materials for enhanced zinc-ion transfer kinetics

The Mo-based oxides/sulfides are promising cathode materials for Zn-ion batteries (ZIBs). However, the volume expansion and poor intrinsic electronic conductivity limit their electrochemical performance. Herein, a strategy of introducing active organic small molecule (ethylenediamine) into the interlayer of the Mo-based oxides/sulfides (MoOS) is reported to solve these shortcomings. The experimental analysis reveals that ethylenediamine (EDA) can regulate the composition ratio of MoO3/MoS2 for its reduction ability, which can improve the electronic conductivity of the EDA-intercalated MoOS (MoOS-EDA). Besides, EDA can efficiently decrease the Zn2+ insertion energy for its strong coordinated ability with Zn2+, in combination with the enhanced interlayer spacing and the strong repulsion with Zn2+ from the non-polar group –CH2CH2 in EDA, leading to enhanced ionic transferring kinetics and Zn2+ storage ability. The theoretical and experimental analysis have confirmed the organic guest and inorganic skeleton all participate in the Zn2+ storage process. As a result, compared with the MoOS cathode, the MoOS-EDA exhibits improved specific capacity (203 vs. 88 mAh/g at 0.1 A/g) and prolonged cycle stability. Moreover, the soft-package cell based on MoOS-EDA cathode also delivers an impressive electrochemical performance. This work provides a strategy to improve the Zn2+ transfer kinetics in MoS2 cathode material towards high-performance ZIBs.