Although ether‐based electrolytes have been extensively applied in anode evaluation of batteries, anodic instability arising from solvent oxidability is always a tremendous obstacle to matching with ...high‐voltage cathodes. Herein, by rational design for solvation configuration, the fully coordinated ether‐based electrolyte with strong resistance against oxidation is reported, which remains anodically stable with high‐voltage Na3V2(PO4)2O2F (NVPF) cathode under 4.5 V (versus Na+/Na) protected by an effective interphase. The assembled graphite//NVPF full cells display superior rate performance and unprecedented cycling stability. Beyond that, the constructed full cells coupling the high‐voltage NVPF cathode with hard carbon anode exhibit outstanding electrochemical performances in terms of high average output voltage up to 3.72 V, long‐term cycle life (such as 95 % capacity retention after 700 cycles) and high energy density (247 Wh kg−1). In short, the optimized ether‐based electrolyte enriches systematic options, the ability to maintain oxidative stability and compatibility with various anodes, exhibiting attractive prospects for application.
By rational design of the solvation configuration, a cation–solvent fully coordinated ether‐based electrolyte with strong oxidation resistance up to 4.5 V (versus Na+/Na) was developed and applied in graphite//NVPF and LHC//NVPF full cells which showed superior rate performance and unprecedented cycling stability.
Impossible voltage plateau regulation for the cathode materials with fixed active elemental center is a pressing issue hindering the development of Na‐superionic‐conductor (NASICON)‐type ...Na3V2(PO4)2F3 (NVPF) cathodes in sodium‐ion batteries (SIBs). Herein, a high‐entropy substitution strategy, to alter the detailed crystal structure of NVPF without changing the central active V atom, is pioneeringly utilized, achieving simultaneous electronic conductivity enhancement and diffusion barrier reduction for Na+, according to theoretical calculations. The as‐prepared carbon‐free high‐entropy Na3V1.9(Ca,Mg,Al,Cr,Mn)0.1(PO4)2F3 (HE‐NVPF) cathode can deliver higher mean voltage of 3.81 V and more advantageous energy density up to 445.5 Wh kg−1, which is attributed by the diverse transition‐metal elemental substitution in high‐entropy crystalline. More importantly, high‐entropy introduction can help realize disordered rearrangement of Na+ at Na(2) active sites, thereby to refrain from unfavorable discharging behaviors at low‐voltage region, further lifting up the mean working voltage to realize a full Na‐ion storage at the high voltage plateau. Coupling with a hard carbon (HC) anode, HE‐NVPF//HC SIB full cells can deliver high specific energy density of 326.8 Wh kg−1 at 5 C with the power density of 2178.9 W kg−1. This route means the unlikely potential regulation in NASICON‐type crystal with unchangeable active center becomes possible, inspiring new ideas on elevating the mean working voltage for SIB cathodes.
A high‐entropy effect is delicately introduced into fluorophosphate cathode for sodium‐ion batteries by in situ partial substitution of active V central atom, preparing a high‐entropy carbon‐free Na3V1.9(Ca,Mg,Al,Cr,Mn)0.1(PO4)2F3 cathode, suppressing the occurrence of detrimental phase transition process in the low‐voltage region, and further lifting up the mean working voltage of pristine Na3V2(PO4)2F3, enhancing sodium storage behavior, rate capability, and cycle performance.
Dual‐ion batteries (DIBs) are a viable option for large‐scale energy storage owing to their high energy density, low cost, and environmental friendliness. However, interfacial instability at both the ...cathode and anode in Li‐graphite DIBs (LG‐DIBs) contributes to poor cycling performance and failed energy storage, severely limiting their application potentials. Herein, a two‐pronged strategy is used to improve the interfacial stability, synergistically stabilizing the graphite cathode by applying a rigid/inert surface coating while building a 3D framework on the lithium anode. The resultant LG‐DIBs are ultrastable and achieve a long cycle life (capacity retention of 80% after 2700 cycles at 200 mA−1) in the all‐climate temperature range from −25 to 40 °C. Ex situ characterization reveals that the cathode–electrolyte interphase on graphite is stabilized by suppressing the electrolyte decomposition and reducing graphite exfoliation. Simultaneously, the framework constructed on the lithium anode induces uniform and dendrite‐free Li deposition owing to its 3D structure. This study not only contributes to the development of practical LG‐DIBs but also points out a promising research direction for other new types of batteries.
A two‐pronged approach is adopted to modify and strengthen the anode electrolyte interphase and cathode electrolyte interphase synergistically in Li‐graphite dual‐ion batteries. The battery life is significantly enhanced in all climates from −25 to 40 °C by inducing homogeneous Li deposition and suppressing successive decomposition of the electrolyte on the graphite cathode.
Single‐atom catalysts (SACs) with highly active sites atomically dispersed on substrates exhibit unique advantages regarding maximum atomic efficiency, abundant chemical structures, and extraordinary ...catalytic performances for multiple important reactions. In particular, M–N–C SACs (M=transition metal atom) demonstrate optimal electrocatalytic activity for the oxygen reduction reaction (ORR) and have attracted extensive attention recently. Despite substantial efforts in fabricating various M–N–C SACs, the principles for regulating the intrinsic electrocatalytic activity of their active sites have not been sufficiently studied. In this Review, we summarize the regulation strategies for promoting the intrinsic electrocatalytic ORR activity of M–N–C SACs by modulation of the center metal atoms, the coordinated atoms, the environmental atoms, and the guest groups. Theoretical calculations and experimental investigations are both included to afford a comprehensive understanding of the structure–performance relationship. Finally, future directions of developing advanced M–N–C SACs for electrocatalytic ORR and other analogous reactions are proposed.
Regulation strategies for enhancing the intrinsic electrocatalytic oxygen reduction reaction activity of M–N–C single‐atom catalysts are summarized in this review. Four components are considered in the optimization of the catalyst: the center metal atoms, the coordinated atoms, the environmental atoms, and the guest groups.
Hydrogen peroxide (H2O2) is a green oxidizer widely involved in a vast number of chemical reactions. Electrochemical reduction of oxygen to H2O2 constitutes an environmentally friendly synthetic ...route. However, the oxygen reduction reaction (ORR) is kinetically sluggish and undesired water serves as the main product on most electrocatalysts. Therefore, electrocatalysts with high reactivity and selectivity are highly required for H2O2 electrosynthesis. In this work, a synergistic strategy is proposed for the preparation of H2O2 electrocatalysts with high ORR reactivity and high H2O2 selectivity. A Co−Nx−C site and oxygen functional group comodified carbon‐based electrocatalyst (named as Co–POC–O) is synthesized. The Co–POC–O electrocatalyst exhibits excellent catalytic performance for H2O2 electrosynthesis in O2‐saturated 0.10 m KOH with a high selectivity over 80% as well as very high reactivity with an ORR potential at 1 mA cm−2 of 0.79 V versus the reversible hydrogen electrode (RHE). Further mechanism study identifies that the Co−Nx−C sites and oxygen functional groups contribute to the reactivity and selectivity for H2O2 electrogeneration, respectively. This work affords not only an emerging strategy to design H2O2 electrosynthesis catalysts with remarkable performance, but also the principles of rational combination of multiple active sites for green and sustainable synthesis of chemicals through electrochemical processes.
A synergistic strategy of rational combination of multiple active sites is proposed for high‐performance H2O2 electrosynthesis. Comodification of atomic Co–Nx–C sites and oxygen functional groups on noble‐metal‐free nanocarbon electrocatalysts synergistically renders high reactivity for oxygen reduction and high selectivity for the two‐electron pathway. Consequently, high H2O2 productivity is achieved through a green and sustainable electrochemical approach.
This research examines the impact of economic policy uncertainty (EPU) on green innovation by using the panel fixed effects model from 2000 to 2017 for the samples of 31 provinces in China. The ...general conclusion is that there exists a positive link from EPU to green innovation, and that the impact of EPU varies significantly among different provinces that have diverse levels of marketization and trade openness. Specifically, provinces with higher marketization and degrees of trade openness have witnessed stronger positive effects from EPU on green innovation, whereas the correlation is rather weak in regions with low levels of those two factors. Our findings serve as a research reference for how governments may boost green innovation in the face of increasing EPU.
As promising cathode for sodium‐ion batteries, Na+ Superionic Conductor (NASICON)‐type materials have attracted attention owing to their excellent structural stability, superior ionic conductivity, ...and small volume expansion. However, the vanadium‐based NASICON‐type cathode with the biotoxicity and exorbitant price of V element and the iron‐based cathode with low mean working voltage as well as the intrinsic poor electronic conductivity of polyanionic compounds hinder their practical applications. Herein, a double‐carbon‐layer decorated heterogeneous composite, Na3V2(PO4)3‐Na3Fe2(PO4)(P2O7) (NVFPP/C/G), is successfully prepared for addressing these limitations. Due to their synergistic effect, NVFPP/C/G exhibits excellent electrochemical performance in half‐cell system and superior full‐cell performance when matched with hard carbon anode. Furthermore, the phase composition, electrode kinetics, and phase transition are confirmed by combined analyses of slow scanning power X‐ray diffraction, high‐resolution transmission electron microscopy, cyclic voltammetry with various scan rates, galvanostatic intermittent titration technique, ex situ X‐ray photoelectron spectra, and in situ X‐ray diffraction. This study portends a promising strategy to utilize composite structure engineering for developing advanced polyanionic cathodes.
A double‐carbon‐layer decorated heterogeneous Na3V2(PO4)3‐Na3Fe2(PO4)(P2O7) composite is proposed as cathode for sodium‐ion batteries. Due to the synergistic effect, it exhibits excellent electrochemical performance in half‐cell system and superior full‐cell performance. The heterogeneous composite structure engineering strategy provides a new approach to design high‐performance polyanionic cathodes for batteries.
In 2014, China proposed medium and long-term low carbon development goals in China-U.S. Joint Statement on Climate Change that the emission of carbon dioxide would reach its peak and the proportion ...of non-fossil energy accounted for the primary energy consumption would increase to 20% in 2030. In order to achieve these goals, the unified carbon emission trading system should be put into effect by 2017, the implementation of the unified carbon emission trading system depends on the effectiveness of the current carbon trading market in China. On the basis of the effective market theory and fair game model, the unit root test and the run test are developed to analyze the carbon emission market of four representative cities in China. The results show that (1) the carbon trading market in China has only achieved weak efficiency, while the semi strong efficiency and the strong efficiency have not been reached; (2) with the expansion of the market scale, the increase of trading volume, the carbon trading market would converge from the state of inefficiency to weak form efficiency gradually, and the carbon trading market in China shows signs of restoring market efficiency.
Due to their potential applications in physiological monitoring, diagnosis, human prosthetics, haptic perception, and human–machine interaction, flexible tactile sensors have attracted wide research ...interest in recent years. Thanks to the advances in material engineering, high performance flexible tactile sensors have been obtained. Among the representative pressure sensing materials, 2D layered nanomaterials have many properties that are superior to those of bulk nanomaterials and are more suitable for high performance flexible sensors. As a class of 2D inorganic compounds in materials science, MXene has excellent electrical, mechanical, and biological compatibility. MXene‐based composites have proven to be promising candidates for flexible tactile sensors due to their excellent stretchability and metallic conductivity. Therefore, great efforts have been devoted to the development of MXene‐based composites for flexible sensor applications. In this paper, the controllable preparation and characterization of MXene are introduced. Then, the recent progresses on fabrication strategies, operating mechanisms, and device performance of MXene composite‐based flexible tactile sensors, including flexible piezoresistive sensors, capacitive sensors, piezoelectric sensors, triboelectric sensors are reviewed. After that, the applications of MXene material‐based flexible electronics in human motion monitoring, healthcare, prosthetics, and artificial intelligence are discussed. Finally, the challenges and perspectives for MXene‐based tactile sensors are summarized.
The latest research advances in preparation strategies and characterization of MXene‐based tactile sensors are comprehensively introduced and discussed. Meanwhile, their applications in human motion monitoring, healthcare, prosthetics, and artificial intelligence are reviewed.
As a cathode for sodium‐ion batteries (SIBs), Na3V2(PO4)2F3 (NVPF) with 3D open framework is a promising candidate due to its high working voltage and large theoretical capacity. However, the severe ...capacity degradation and poor rate capability hinder its practical applications. The present study demonstrated the optimization of Na‐storage performance of NVPF via delicate lattice modulation. Aliovalent substitution of V3+ at Na+ in NVPF induces the generation of electronic defects and expansion of Na+‐migration channels, resulting in the enhancement in electronic conductivity and acceleration of Na+‐migration kinetics. It is disclosed that the formed stronger NaO bonds with high ionicity than VO bonds lead to the significant increase in structural stability and ionicity in the Na+‐substituted NVPF (NVPF‐Nax). The aforementioned effects of Na+ substitution achieve the unprecedented electrochemical performance in the optimized Na3.14V1.93Na0.07(PO4)2F3 (NVPF‐Na0.07). As a result, NVPF‐Na0.07 delivers a high‐rate capability (77.5 mAh g−1 at 20 C) and ultralong cycle life (only 0.027% capacity decay per cycle over 1000 cycles at 10 C). Sodium‐ion full cells are designed using NVPF‐Na0.07 as cathode and Se@reduced graphene oxide as anode. The full cells exhibit excellent wide‐temperature electrochemical performance from −25 to 25°C with an outstanding rate capability (96.3 mAh g−1 at 20 C). Furthermore, it delivered an excellent cycling performance over 300 cycles with a capacity retention exceeding 90% at 0.5 C under different temperatures. This study demonstrates a feasible strategy for the development of advanced cathode materials with excellent electrochemical properties to achieve high‐efficiency energy storage.
An advanced Na3.14V1.93Na0.07(PO4)2F3 cathode with high ionicity and excellent energy‐storage performance is prepared via aliovalent substitution of V3+ at Na+ sites. It exhibits the higher structural stability and improved electron/ion‐transport kinetics than the pristine Na3V2(PO4)2F3 owing to the stronger NaO and VO bonds, thereby extending the cycle life of NASICON cathode materials.
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