Conventional ion batteries utilizing metallic ions as the single charge carriers are limited by the insufficient abundance of metal resources. Although supercapacitors apply both cations and anions ...to store energy through absorption and/or Faradic reactions occurring at the interfaces of the electrode/electrolyte, the inherent low energy density hinders its application. The graphite‐cathode‐based dual‐ion battery possesses a higher energy density due to its high working potential of nearly 5 V. However, such a battery configuration suffers from severe electrolyte decomposition and exfoliation of the graphite cathode, rendering an inferior cycle life. Herein, a new surface‐modification strategy is developed to protect the graphite cathode from the anion salvation effect and the deposition derived from electrolyte decomposition by generating an artificial solid electrolyte interphase (SEI). Such SEI‐modified graphite exhibits superior cycling stability with 96% capacity retention after 500 cycles under 200 mA g−1 at the upper cutoff voltage of 5.0 V, which is much improved compared with the pristine graphite electrode. Through several ex situ studies, it is revealed that the artificial SEI greatly stabilizes the interfaces of the electrode/electrolyte after reconstruction and gradual establishment of the optimal anion‐transport path. The findings shed light on a new avenue toward promoting the performance of the dual‐ion battery (DIB) and hence to make it practical finally.
An artificial layer of a solid electrolyte interphase is fabricated on a graphite cathode for a dual‐ion battery (DIB). Such surface modification can alleviate the electrolyte decomposition at the high working voltage of the anion de‐/intercalation processes and the solvation effect of anions, much improving the cycling stability of the Li//graphite DIB.
Transition metal selenides have been widely used in alkali metal ion batteries owing to their high specific capacities and low cost. However, their reaction kinetics and structural stability are ...usually poor during cycling, along with ambiguous differences in Li/Na/K‐storage behaviors. Herein, it is revealed that ZnSe possesses better Na+‐diffusion kinetics (including lower diffusion barrier, smaller activation energy, and higher diffusion coefficients) in comparison with Li+ and K+, as evidenced by theoretical calculations and electrochemical studies. The architectural designs of ZnSe‐based anode, including nitrogen‐doped carbon (N,C) and 3D ordered hierarchical pores (3DOHP) to form a 3DOHP ZnSe@N,C hybrid combined with regulating solid electrolyte interphase (SEI), significantly enhance Na+ reaction kinetics and accommodate volume changes. The resulting 3DOHP ZnSe@N,C electrodes exhibit outstanding rate capability and good cycling stability (241.6 mAh g−1 in sodium‐ion batteries (SIBs) at 10 A g−1 after 800 cycles), originating from improved electrical conductivity and shortened ion diffusion paths, accompanied by ultrathin and stable SEI with less Na2CO3/NaF in organic components and boosted Na2Se adsorption as sodiation. Moreover, the Na‐storage mechanism in 3DOHP ZnSe@N,C hybrid is further revealed by in situ studies. Accordingly, this study provides a new perspective for designing high‐performance electrode materials for SIBs.
A 3D ordered hierarchical porous ZnSe@N‐doped carbon hybrid with higher Na+ diffusion kinetics than Li+ and K+ is fabricated. Originating from architectural advantages and optimization of electrolytes, the hybrid delivers a low diffusion barrier and activation energy of Na+, accompanied by the formation of ultrathin solid electrolyte interphase to yield a long cycle life even at 10 A g−1 for sodium‐ion batteries.
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.
Hard carbon is regarded as a promising anode material for sodium‐ion batteries (SIBs). However, it usually suffers from the issues of low initial Coulombic efficiency (ICE) and poor rate performance, ...severely hindering its practical application. Herein, a flexible, self‐supporting, and scalable hard carbon paper (HCP) derived from scalable and renewable tissue is rationally designed and prepared as practical additive‐free anode for room/low‐temperature SIBs with high ICE. In ether electrolyte, such HCP achieves an ICE of up to 91.2% with superior high‐rate capability, ultralong cycle life (e.g., 93% capacity retention over 1000 cycles at 200 mA g−1) and outstanding low‐temperature performance. Working mechanism analyses reveal that the plateau region is the rate‐determining step for HCP with a lower electrochemical reaction kinetics, which can be significantly improved in ether electrolyte.
A self‐supporting, flexible, additive‐free and scalable hard carbon paper (HCP) derived from tissue is rationally developed, and it achieves outstanding Na‐storage properties in terms of high initial Coulombic efficiency (91.2%), superior high‐rate capability, ultralong cyclic stability, as well as outstanding low‐T performance in ether electrolyte. More significantly, the Na‐storage and capacity attenuation mechanism of the HCP anode is revealed.
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.
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.
Polyanion‐type phosphate materials are highly promising cathode candidates for next‐generation batteries due to their excellent structural stability during cycling; however, their poor conductivity ...has impeded their development. Isostructural and multivalent anion substitution combined with carbon coating is proposed to greatly improve the electrochemical properties of phosphate cathode in sodium‐ion batteries (SIBs). Specifically, multivalent tetrahedral SiO44− substitute for PO43− in Na3V2(PO4)3 (NVP) lattice, preparing the optimal Na3.1V2(PO4)2.9(SiO4)0.1 with high‐rate capability (delivering a high capacity of 82.5 mAh g−1 even at 20 C) and outstanding cyclic stability (≈98% capacity retention after 500 cycles at 1 C). Theoretical calculation and experimental analyses reveal that the anion‐substituted Na3.1V2(PO4)2.9(SiO4)0.1 reduces the bandgap of NVP lattice and enhanced its structural stability, Na+‐diffusion kinetics and electronic conductivity. This strategy of multivalent and isostructural anion substitution chemistry provides a new insight to develop advanced phosphate cathodes.
Na3+xV2(PO4)3−x(SiO4)x (0 ≤ x ≤ 0.15) cathode materials are prepared via substitution of the inactive PO43− sites in Na3V2(PO4)3 with isostructural SiO44− anions. The substitution effects on crystal structure, electrochemical properties, Na+‐diffusion kinetics and electronic conductivity are systematically investigated. Multivalent and isostructural anionic substitution provides a new strategy for designing polyanionic materials of sodium‐ion batteries.
It remains a great challenge to design and manufacture battery‐type supercapacitors with satisfactory flexibility, appropriate mechanical property, and high energy density under high power density. ...Herein, a concept of porous engineering is proposed to simply prepare two‐layered bimetallic heterojunction with porous structures. This concept is successfully applied in fabrication of flexible electrode based on CuO‐Co(OH)2 lamella on Cu‐plated carbon cloth (named as CPCC@CuO@Co(OH)2). The unique structure brings the electrode a high specific capacity of 3620 mF cm−2 at 2 mA cm−2 and appropriate mechanical properties with Young's modulus of 302.0 MPa. Density functional theory calculations show that porous heterojunction provides a higher intensity of electron state density near the Fermi level (E–Ef = 0 eV), leading to a highly conductive CPCC@CuO@Co(OH)2 electrode with both efficient charge transport and rapid ion diffusion. Notably, the supercapacitor assembled from CPCC@CuO@Co(OH)2//CC@AC shows high energy density of 127.7 W h kg−1 at 750.0 W kg−1, remarkable cycling performance (95.53% capacity maintaining after 10 000 cycles), and desired mechanical flexibility. The methodology and results in this work will accelerate the transformative developments of flexible energy storage devices in practical applications.
A universal strategy for constructing lamellar porous heterojunctions is developed to fabricate flexible electrodes for high‐performance energy storage devices. The resulted electrodes have a unique energy band structure with higher electronic density of states near the Fermi level and high conductivity, which achieve efficient charge transport and shortened the ion diffusion distance.
Flexible Na/K‐ion batteries (NIBs/KIBs) exhibit great potential applications and have drawn much attention due to the continuous development of flexible electronics. However, there are still many ...huge challenges, mainly the design and construction of flexible electrodes (cathode and anode) with outstanding electrochemical properties. In this work, a unique approach to prepare flexible electrode is proposed by utilizing the commercially available cotton cloth–derived carbon cloth (CC) as a flexible anode and the substrate of a cathode. The binder‐free, self‐supporting, and flexible cathodes (FCC@N/KPB) are prepared by growing Prussian blue microcubes on the flexible CC (FCC). Na/K‐ion full batteries (FCC//FCC@N/KPB) are assembled by using FCC and FCC@N/KPB as anode and cathode, respectively. Electrochemical performance, mechanical flexibility, and practicability of FCC//FCC@N/KPB Na/K‐ion full batteries are evaluated in both coin cells and flexible pouch cells, demonstrating their superior energy‐storage properties (excellent rate performance and cycling stability) and remarkable flexibility (they can work under different bending states). This work provides a new and profound strategy to design flexible electrodes, promoting the development of flexible NIBs/KIBs to be practical and sustainable.
Flexible Na/K‐ion full batteries with promising energy‐storage performance and remarkable flexibility are assembled by utilizing the commercially available cotton cloth–derived carbon cloth as flexible anode and cathode substrate. The flexible cathodes are prepared by growing Prussian blue microcubes on the flexible substrate. Electrochemical performance, flexibility, and practicability of batteries are evaluated in both coin cells and flexible pouch cells.
With the rapidly growing demand for low‐cost and safe energy storage, the advanced battery concepts have triggered strong interests beyond the state‐of‐the‐art Li‐ion batteries (LIBs). Herein, a ...novel hybrid Li/Na‐ion full battery (HLNIB) composed of the high‐energy and lithium‐free Na3V2(PO4)2O2F (NVPOF) cathode and commercial graphite anode mesophase carbon micro beads is for the first time designed. The assembled HLNIBs exhibit two high working voltage at about 4.05 and 3.69 V with a specific capacity of 112.7 mA h g−1. Its energy density can reach up to 328 W h kg−1 calculated from the total mass of both cathode and anode materials. Moreover, the HLNIBs show outstanding high‐rate capability, long‐term cycle life, and excellent low‐temperature performance. In addition, the reaction kinetics and Li/Na‐insertion/extraction mechanism into/out NVPOF is preliminarily investigated by the galvanostatic intermittent titration technique and ex situ X‐ray diffraction. This work provides a new and profound direction to develop advanced hybrid batteries.
A novel Li/Na‐ion hybrid battery with high working voltage and superior electrochemical and low‐temperature properties is designed and assembled by using lithium‐free Na3V2(PO4)2O2F (NVPOF) and commercial graphite as cathode and anode, respectively. The electrode kinetics and Li/Na‐insertion/extraction processes into/out the NVPOF cathode are preliminarily studied by the galvanostatic intermittent titration technique and ex situ X‐ray diffraction.
