Incorporation of N,S‐codoped nanotube‐like carbon (N,S‐NTC) can endow electrode materials with superior electrochemical properties owing to the unique nanoarchitecture and improved kinetics. Herein, ...α‐MnS nanoparticles (NPs) are in situ encapsulated into N,S‐NTC, preparing an advanced anode material (α‐MnS@N,S‐NTC) for lithium‐ion/sodium‐ion batteries (LIBs/SIBs). It is for the first time revealed that electrochemical α → β phase transition of MnS NPs during the 1st cycle effectively promotes Li‐storage properties, which is deduced by the studies of ex situ X‐ray diffraction/high‐resolution transmission electron microscopy and electrode kinetics. As a result, the optimized α‐MnS@N,S‐NTC electrode delivers a high Li‐storage capacity (1415 mA h g−1 at 50 mA g−1), excellent rate capability (430 mA h g−1 at 10 A g−1), and long‐term cycling stability (no obvious capacity decay over 5000 cycles at 1 A g−1) with retained morphology. In addition, the N,S‐NTC‐based encapsulation plays the key roles on enhancing the electrochemical properties due to its high conductivity and unique 1D nanoarchitecture with excellent protective effects to active MnS NPs. Furthermore, α‐MnS@N,S‐NTC also delivers high Na‐storage capacity (536 mA h g−1 at 50 mA g−1) without the occurrence of such α → β phase transition and excellent full‐cell performances as coupling with commercial LiFePO4 and LiNi0.6Co0.2Mn0.2O2 cathodes in LIBs as well as Na3V2(PO4)2O2F cathode in SIBs.
α‐MnS nanoparticles are in situ encapsulated into N,S‐codoped nanotube‐like carbon (α‐MnS@N,S‐NTC) as an advanced anode for Li/Na‐ion batteries. The α → β phase transition during the 1st cycle in LIBs is for the first time revealed by ex situ X‐ray diffraction and high‐resolution transmission electron microscopy studies, which improves the electrode kinetics and Li‐storage properties. α‐MnS@N,S‐NTC also exhibits superior performance in Li/Na‐ion half/full cells.
In this work, a flexible and self-supporting P-doped carbon cloth (FPCC), which is composed of interwoven mesh of hollow microtubules with porous carbon walls, is prepared via a vacuum-sealed doping ...technology by employing the commercially available cotton cloth as sustainable and scalable raw material. When directly used as binder-free anode for sodium-ion batteries, the as-prepared FPCC delivers superior Na-storage properties in terms of specific capacity up to 242.4 mA h g–1, high initial Coulombic efficiency of ∼72%, excellent rate capabilities (e.g., 123.1 mA h g–1 at a high current of 1 A g–1), and long-term cycle life (e.g., ∼88% capacity retention after even 600 cycles). All these electrochemical data are better than the undoped carbon cloth control, demonstrating the significance of P-doping to enhance the Na-storage properties of cotton-derived carbon anode. Furthermore, the technologies of electrochemical impedance spectroscopy and galvanostatic intermittent titration technique are implemented to disclose the decrease of charge transfer resistance and improvement of Na-migration kinetics, respectively.
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.
As a promising alternative for lithium ion batteries, room-temperature sodium ion batteries (SIBs) have become one significant research frontier of energy storage devices although there are still ...many difficulties to be overcome. For the moment, the studies still concentrate on the preparation of new electrode materials for SIBs to meet the applicability. Herein, one new P2-Na2/3Ni1/3Mn5/9Al1/9O2 (NMA) cathode material is successfully prepared via a simple and facile liquid-state method. The prepared NMA is layered transition metal oxide, which can keep stable crystal structure during sodiation/desodiation as demonstrated by the ex situ X-ray diffraction, and its electrochemical properties can be further enhanced by connecting the cake-like NMA microparticles with reduced graphene oxide (RGO) using a ball milling method. Electrochemical tests show that the formed RGO-connected NMA (NMA/RGO) can deliver a higher reversible capacity of up to 138 mAh g(-1) at 0.1 C and also exhibit a superior high-rate capabilities and cycling stability in comparison to pure NMA. The much improved properties should be attributed to the reduced particle size and improvement of electrical conductivity and apparent Na(+) diffusion due to RGO incorporation, which is comprehensively verified by the electrochemical technologies of galvanostatic intermittent titration technique, electrochemical impedance spectroscopy and cyclic voltammetry at various scan rate as well as ex-situ X-ray diffraction studies.
Covalent organic frameworks (COFs) have received increased interest in recent years as an advanced class of materials. By virtue of the available monomers, multiple conformations and various ...linkages, COFs offer a wide range of opportunities for complex structural design and specific functional development of materials, which has facilitated the widespread application in many fields, including multi‐valent metal ion batteries (MVMIBs), described as the attractive candidate replacing lithium‐ion batteries (LIBs). With their robust skeletons, diverse pores, flexible structures and abundant functional groups, COFs are expected to help realize a high performance MVMIBs. In this review, we present an overview of COFs, describe advances in topology design and synthetic reactions, and study the application of COFs in MVMIBs, as well as discuss challenges and solutions in the preparation of COFs electrodes, in the hope of providing constructive insights into the future direction of COFs.
Covalent organic frameworks (COFs) offer an opportunity for complex structural design and specific functional development, facilitating, for example, the applications of multi‐valent metal ion batteries (Zn2+, Mg2+, Al3+). This comprehensive review describes COF synthesis and applications, provides advances in topology design and synthetic reactions, surveys the application of COFs in multi‐valent ion batteries, discusses the key issues of COF electrodes, and predicts future applications.
In recent years, rechargeable aqueous zinc-ion batteries (ZIBs) have shown extraordinary potential due to their safety, nontoxicity, sustainable zinc resources, and low price. However, the lack of ...suitable cathode materials hinders the development of ZIBs. Recently, layered phosphates have been widely used as cathode materials. As one typical phosphate cathode, vanadium oxyphosphate (VOPO4) has inherently low electronic conductivity and structural dissolution in electrochemical reactions, limiting its development. To solve these problems, VOPO4/C is prepared by combining multifunctional carbon material with a VOPO4 interlayer and an external surface, which not only improves the electronic conductivity of the composite material but also effectively inhibits the dissolution of VOPO4 in the electrolyte. As a result, the prepared VOPO4/C could deliver a reversible capacity of 140 mA h g–1 at a current density of 100 mA g–1. Furthermore, the rate performance of the VOPO4/C composite has also been improved significantly. In the process of charging and discharging, zinc ions in the composite show perfect intercalate and deintercalate performance.
Based on the favorable ionic conductivity and structural stability, sodium superionic conductor (NASICON) materials especially utilizing multivalent redox reaction of vanadium are one of the most ...promising cathodes in sodium‐ion batteries (SIBs). To further boost their application in large‐scale energy storage production, a rational strategy is to tailor vanadium with earth‐abundant and cheap elements (such as Fe, Mn), reducing the cost and toxicity of vanadium‐based NASICON materials. Here, the Na3.05V1.03Fe0.97(PO4)3 (NVFP) is synthesized with highly conductive Ketjen Black (KB) by ball‐milling assisted sol‐gel method. The pearl‐like KB branch chains encircle the NVFP (p‐NVFP), the segregated particles possess promoted overall conductivity, balanced charge, and modulated crystal structure during electrochemical progress. The p‐NVFP obtains significantly enhanced ion diffusion ability and low volume change (2.99%). Meanwhile, it delivers a durable cycling performance (87.7% capacity retention over 5000 cycles at 5 C) in half cells. Surprisingly, the full cells of p‐NVFP reveal a remarkable capability of 84.9 mAh g−1 at 20 C with good cycling performance (capacity decay rate is 0.016% per cycle at 2 C). The structure modulation of the p‐NVFP provides a rational design on the superiority of others to be put into practice.
Ketjen Black (KB) branch chains encircle the Na3.05V1.03Fe0.97(PO4)3 (NVFP) like wearing “pearl,” making the segregated particles link to access the overall conductivity and activating the unusual structural distortion of FeO6 in NVFP during electrochemical progress, thus stimulating plenty of Na+ de/intercalation at plateau region with reversible phase transition and acquiring a favorable rate performance and durable cycling lifespan under fine volume variation.
Abstract
As a sodium superionic conductor, Mn‐rich phosphate of Na
3.4
Mn
1.2
Ti
0.8
(PO
4
)
3
is considered as one of the promising cathodes for sodium‐ion batteries owing to its good thermodynamic ...stability and high working voltage. However, Na
3.4
Mn
1.2
Ti
0.8
(PO
4
)
3
is faced with low electronic conductivity, poor cycling stability and complex phase transition caused by multi‐electron transfers, which limits its practical application. Herein, an anion‐regulated strategy is proposed to optimize the Mn‐rich Na
3.4
Mn
1.2
Ti
0.8
(PO
4
)
3
phosphate cathode. After introducing F anions into the lattice, the rate performance is improved from 60.5 to 72.8 mAh g
−1
at 20 C. Ascribed to unique structure design, the reaction kinetics of Na
3.4
Mn
1.2
Ti
0.8
(PO
4
)
3
are significantly improved, as demonstrated by cyclic voltammetry at varied scan rates and galvanostatic intermittent titration technique. The generated M‐F bond inhibits Jahn–Teller effect with an improved cycle stability (85.8 mAh g
−1
after 1000 cycles at 5 C with 94.3% capacity retention). Interestingly, reaction mechanism of Na
3.4
Mn
1.2
Ti
0.8
(PO
4
)
3
with the complex two‐phase and solid solution reactions changes to the whole solid solution reaction after fluorine substitution, and leads to a smaller volume change of 5.41% during reaction processes, which is verified by in situ X‐ray diffraction. This anion regulation strategy provides a new method for designing the high‐performance phosphate cathode materials of sodium‐ion batteries.
In this article, an effective strategy ( viz. , constructing multiple heterointerfaces) is proposed to develop superior electrode materials for sodium-ion battery (SIB), which is the most promising ...alternative to market-dominant lithium-ion battery for stationary energy storage. In the as-prepared heterogeneous-SnO 2 /Se/graphene (h-SSG) composite, there exists multiple phase interfaces, including heterointerfaces between tetragonal and orthorhombic SnO 2 (t-/o-SnO 2 ) in the heterogeneous SnO 2 nanojunctions and two phase interfaces between t/o-SnO 2 and amorphous Se. These multiple phase interfaces promise the much improved Na storage properties of h-SSG when compared to four controls without such multiple heterointerfaces because the multiple built-in electric fields at the heterointerfaces can significantly boost the surface reaction kinetics and facilitate charge transport as demonstrated by kinetics analyses, theoretical calculations and contrastive electrochemical tests. Moreover, h-SSG also exhibits superior Na-ion full cell performance when coupled with a high-voltage Na 3 V 2 (PO 4 ) 2 O 2 F cathode. In view of the universality of the heterointerface-based enhancement effect on surface reaction and charge transport kinetics and the facile preparation procedures, the present strategy should be universal to develop other superior electrode materials for high-performance SIBs and other batteries for future energy storage applications.
Catalytic performance of two model enzymes, Penicillium expansum lipase (PEL) and mushroom tyrosinase, was examined in aqueous solution with addition of 14 different ionic liquids (ILs) and has been ...found to correlate well with the IL's kosmotropic/chaotropic properties, which are assessed by the viscosity B coefficients (B+ for cations and B- for anions). The activity and stability of PEL were similarly correlated with B+ values but not with B- of the ILs tested. PEL can be activated and stabilized by addition of ILs (e.g., 5.2-fold activation and 1.4-fold stabilization in the presence of 0.63 M cholineAc and 0.27 M NHMe3MeSO3, respectively). Choline ILs activated PEL but imidazolium ones deactivated it. The results indicate that the IL cations play a crucial role in affecting the enzyme performance and that ammonium ILs composed of chaotropic cations (favorably with H-bonding capability) and kosmotropic anions are favored for enzyme catalysis. The Hofmeister effect of ILs on PEL was confirmed by the kinetic and thermostability studies and structural analysis on tyrosinase. Our investigations on both enzymes have thus demonstrated that ILs can affect the enzyme functioning through the Hofmeister effect, and the mechanisms have been discussed in terms of the influence of the IL cations and anions on the surface pH, active site conformation, and catalytic mechanism of each specific enzyme, following the Hofmeister series.
