Highlights
A novel strategy of employing Cu nanowire networks to realize superior long-life and high-rate zinc anodes was proposed.
Cu nanowire networks could stabilize zinc anodes from multiple ...aspects, including homogenizing surface electric field and Zn
2+
concentration field, inhibiting side reactions and inducing uniform zinc nucleation/deposition.
Facets and edge sites of Cu nanowires, especially the latter ones, were revealed to be highly zincophilic.
Zn-based electrochemical energy storage (EES) systems have received tremendous attention in recent years, but their zinc anodes are seriously plagued by the issues of zinc dendrite and side reactions (e.g., corrosion and hydrogen evolution). Herein, we report a novel strategy of employing zincophilic Cu nanowire networks to stabilize zinc anodes from multiple aspects. According to experimental results, COMSOL simulation and density functional theory calculations, the Cu nanowire networks covering on zinc anode surface not only homogenize the surface electric field and Zn
2+
concentration field, but also inhibit side reactions through their hydrophobic feature. Meanwhile, facets and edge sites of the Cu nanowires, especially the latter ones, are revealed to be highly zincophilic to induce uniform zinc nucleation/deposition. Consequently, the Cu nanowire networks-protected zinc anodes exhibit an ultralong cycle life of over 2800 h and also can continuously operate for hundreds of hours even at very large charge/discharge currents and areal capacities (e.g., 10 mA cm
−2
and 5 mAh cm
−2
), remarkably superior to bare zinc anodes and most of currently reported zinc anodes, thereby enabling Zn-based EES devices to possess high capacity, 16,000-cycle lifespan and rapid charge/discharge ability. This work provides new thoughts to realize long-life and high-rate zinc anodes.
Highlights
Various MOF materials were synthesized and investigated as ZIB cathodes.
A long-term stable ZIF-8@Zn anode was proposed by coating ZIF-8 material on the surface of zinc foils.
...High-performance aqueous ZIBs were constructed using the Mn(BTC) cathode and the ZIF-8@Zn anode.
Rechargeable aqueous zinc-ion batteries (ZIBs) have been gaining increasing interest for large-scale energy storage applications due to their high safety, good rate capability, and low cost. However, the further development of ZIBs is impeded by two main challenges: Currently reported cathode materials usually suffer from rapid capacity fading or high toxicity, and meanwhile, unstable zinc stripping/plating on Zn anode seriously shortens the cycling life of ZIBs. In this paper, metal–organic framework (MOF) materials are proposed to simultaneously address these issues and realize high-performance ZIBs with Mn(BTC) MOF cathodes and ZIF-8-coated Zn (ZIF-8@Zn) anodes. Various MOF materials were synthesized, and Mn(BTC) MOF was found to exhibit the best Zn
2+
-storage ability with a capacity of 112 mAh g
−1
. Zn
2+
storage mechanism of the Mn(BTC) was carefully studied. Besides, ZIF-8@Zn anodes were prepared by coating ZIF-8 MOF material on Zn foils. Unique porous structure of the ZIF-8 coating guided uniform Zn stripping/plating on the surface of Zn anodes. As a result, the ZIF-8@Zn anodes exhibited stable Zn stripping/plating behaviors, with 8 times longer cycle life than bare Zn foils. Based on the above, high-performance aqueous ZIBs were constructed using the Mn(BTC) cathodes and the ZIF-8@Zn anodes, which displayed an excellent long-cycling stability without obvious capacity fading after 900 charge/discharge cycles. This work provides a new opportunity for high-performance energy storage system.
Highlights
Dendrite-free stable Zn plating/stripping was achieved for over 500 h at 2 mA cm
−2
.
No short-circuit for 10 mAh cm
−2
of Zn plating.
Zn|MnO
2
cells delivered nearly 100% capacity ...retention over 2000 cycles.
Owing to the merits of low cost, high safety and environmental benignity, rechargeable aqueous Zn-based batteries (ZBs) have gained tremendous attention in recent years. Nevertheless, the poor reversibility of Zn anodes that originates from dendrite growth, surface passivation and corrosion, severely hinders the further development of ZBs. To tackle these issues, here we report a Janus separator based on a Zn-ion conductive metal–organic framework (MOF) and reduced graphene oxide (rGO), which is able to regulate uniform Zn
2+
flux and electron conduction simultaneously during battery operation. Facilitated by the MOF/rGO bifunctional interlayers, the Zn anodes demonstrate stable plating/stripping behavior (over 500 h at 1 mA cm
−2
), high Coulombic efficiency (99.2% at 2 mA cm
−2
after 100 cycles) and reduced redox barrier. Moreover, it is also found that the Zn corrosion can be effectively retarded through diminishing the potential discrepancy on Zn surface. Such a separator engineering also saliently promotes the overall performance of Zn|MnO
2
full cells, which deliver nearly 100% capacity retention after 2000 cycles at 4 A g
−1
and high power density over 10 kW kg
−1
. This work provides a feasible route to the high-performance Zn anodes for ZBs.
Highlights
A surface engineering strategy was proposed to design hierarchically porous structure on fibrous carbon cathodes with O/N heteroatom functional groups.
High-energy and anti-self-discharge ...Zn-ion hybrid supercapacitors (ZHSs) were realized.
ZHS electrochemistry was investigated and new insights were provided.
Aqueous Zn-ion hybrid supercapacitors (ZHSs) are increasingly being studied as a novel electrochemical energy storage system with prominent electrochemical performance, high safety and low cost. Herein, high-energy and anti-self-discharge ZHSs are realized based on the fibrous carbon cathodes with hierarchically porous surface and O/N heteroatom functional groups. Hierarchically porous surface of the fabricated free-standing fibrous carbon cathodes not only provides abundant active sites for divalent ion storage, but also optimizes ion transport kinetics. Consequently, the cathodes show a high gravimetric capacity of 156 mAh g
−1
, superior rate capability (79 mAh g
−1
with a very short charge/discharge time of 14 s) and exceptional cycling stability. Meanwhile, hierarchical pore structure and suitable surface functional groups of the cathodes endow ZHSs with a high energy density of 127 Wh kg
−1
, a high power density of 15.3 kW kg
−1
and good anti-self-discharge performance. Mechanism investigation reveals that ZHS electrochemistry involves cation adsorption/desorption and Zn
4
SO
4
(OH)
6
·5H
2
O formation/dissolution at low voltage and anion adsorption/desorption at high voltage on carbon cathodes. The roles of these reactions in energy storage of ZHSs are elucidated. This work not only paves a way for high-performance cathode materials of ZHSs, but also provides a deeper understanding of ZHS electrochemistry.
Highlights
This work is a new guide for the design of on-chip energy integrated systems toward the goal of developing highly safe, economic, and long-life smart wearable electronics.
The biomass ...kelp-carbon based on unique 3D micro-/nanostructure combined with multivalent ion storage contributes to high capacity of the Zn-ion hybrid capacitor.
The flexible solar-charging self-powered system with printed Zn-ion hybrid micro-capacitor as energy storage module exhibits fast photoelectric conversion/storage rate, good mechanical robustness, and cyclic stability.
Wearable self-powered systems integrated with energy conversion and storage devices such as solar-charging power units arouse widespread concerns in scientific and industrial realms. However, their applications are hampered by the restrictions of unbefitting size matching between integrated modules, limited tolerance to the variation of input current, reliability, and safety issues. Herein, flexible solar-charging self-powered units based on printed Zn-ion hybrid micro-capacitor as the energy storage module is developed. Unique 3D micro-/nano-architecture of the biomass kelp-carbon combined with multivalent ion (Zn
2+
) storage endows the aqueous Zn-ion hybrid capacitor with high specific capacity (196.7 mAh g
−1
at 0.1 A g
−1
). By employing an in-plane asymmetric printing technique, the fabricated quasi-solid-state Zn-ion hybrid micro-capacitors exhibit high rate, long life and energy density up to 8.2 μWh cm
−2
. After integrating the micro-capacitor with organic solar cells, the derived self-powered system presents outstanding energy conversion/storage efficiency (
η
overall
= 17.8%), solar-charging cyclic stability (95% after 100 cycles), wide current tolerance, and good mechanical flexibility. Such portable, wearable, and green integrated units offer new insights into design of advanced self-powered systems toward the goal of developing highly safe, economic, stable, and long-life smart wearable electronics.
Highlights
Pourbaix diagram of Mn–Zn–H
2
O system was used to analyze the charge–discharge processes of Zn/MnO
2
batteries.
Electrochemical reactions with the participation of various ions inside ...Zn/MnO
2
batteries were revealed.
A detailed explanation of phase evolution inside Zn/MnO
2
batteries was provided.
Aqueous rechargeable Zn/MnO
2
zinc-ion batteries (ZIBs) are reviving recently due to their low cost, non-toxicity, and natural abundance. However, their energy storage mechanism remains controversial due to their complicated electrochemical reactions. Meanwhile, to achieve satisfactory cyclic stability and rate performance of the Zn/MnO
2
ZIBs, Mn
2+
is introduced in the electrolyte (e.g., ZnSO
4
solution), which leads to more complicated reactions inside the ZIBs systems. Herein, based on comprehensive analysis methods including electrochemical analysis and Pourbaix diagram, we provide novel insights into the energy storage mechanism of Zn/MnO
2
batteries in the presence of Mn
2+
. A complex series of electrochemical reactions with the co-participation of Zn
2+
, H
+
, Mn
2+
, SO
4
2−
, and OH
−
were revealed. During the first discharge process, co-insertion of Zn
2+
and H
+
promotes the transformation of MnO
2
into Zn
x
MnO
4
, MnOOH, and Mn
2
O
3
, accompanying with increased electrolyte pH and the formation of ZnSO
4
·3Zn(OH)
2
·5H
2
O. During the subsequent charge process, Zn
x
MnO
4
, MnOOH, and Mn
2
O
3
revert to α-MnO
2
with the extraction of Zn
2+
and H
+
, while ZnSO
4
·3Zn(OH)
2
·5H
2
O reacts with Mn
2+
to form ZnMn
3
O
7
·3H
2
O. In the following charge/discharge processes, besides aforementioned electrochemical reactions, Zn
2+
reversibly insert into/extract from α-MnO
2
, Zn
x
MnO
4
, and ZnMn
3
O
7
·3H
2
O hosts; ZnSO
4
·3Zn(OH)
2
·5H
2
O, Zn
2
Mn
3
O
8
, and ZnMn
2
O
4
convert mutually with the participation of Mn
2+
. This work is believed to provide theoretical guidance for further research on high-performance ZIBs.
CsPbBr3 perovskite quantum dots (PQDs)/ethylene vinyl acetate (EVA) composite films were prepared via a one-step method; on the basis of this, both supersaturated recrystallization of CsPbBr3 PQDs ...and dissolution of EVA were realized in toluene. The prepared films display outstanding green-emitting performance with high color purity of 92% and photoluminescence (PL) quantum yield of 40.5% at appropriate CsPbBr3 PQD loading. They possess long-term stable luminescent properties in the air and in water, benefiting from the effective protection of CsPbBr3 PQDs by the EVA matrix. Besides, the prepared CsPbBr3 PQDs/EVA films are flexible enough to be repeatedly bent for 1000 cycles while keeping unchanged the PL intensity. The optical properties of the CsPbBr3 PQDs/EVA films in white light-emitting diodes were also studied by experiments and theoretical simulation. Overall, facile preparation process, good long-term stability, and high flexibility allow our green-emitting CsPbBr3 PQDs/EVA films to be applied in lighting applications and flexible displays.
Zinc ion batteries (ZIBs) have attracted extensive attention in recent years, benefiting from their high safety, eco-friendliness, low cost, and high energy density. Although many cathode materials ...for ZIBs have been developed, the poor stability of zinc anodes caused by uneven deposition/stripping of zinc has inevitably limited the practical application of ZIBs. Herein, we report a highly stable 3D Zn anode prepared by electrodepositing Zn on a chemically etched porous copper skeleton. The inherent excellent electrical conductivity and open structure of the 3D porous copper skeleton ensure the uniform deposition/stripping of Zn. The 3D Zn anode exhibits reduced polarization, stable cycling performance, and almost 100% Coulombic efficiency as well as fast electrochemical kinetics during repeated Zn deposition/stripping processes for 350 h. Furthermore, full cells with a 3D Zn anode, ultrathin MnO2 nanosheet cathode, and Zn2+-containing aqueous electrolyte delivered a record-high capacity of 364 mAh g–1 at a current density of 0.1 A g–1 and good cycling stability with a retained capacity of 173 mAh g–1 after 300 charge/discharge cycles at 0.4 A g–1. This work provides a pathway for developing high-performance ZIBs.
An electrochemically induced transformation of vanadium oxides is reported to realize high-capacity, fast-rate and long-life cathode materials for rechargeable aqueous zinc batteries.
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...•An electrochemically induced transformation of vanadium oxides is reported.•Such an in-situ transformation realizes high-capacity, high-rate and long-life cathode materials for zinc-ion batteries.•New insights into Zn2+-storage electrochemistry are provided.
Rechargeable aqueous zinc-ion batteries (ZIBs) have become a research hotspot in recent years, due to their huge potential for high-energy, fast-rate, safe and low-cost energy storage. To realize good electrochemical properties of ZIBs, cathode materials with prominent Zn2+ storage capability are highly needed. Herein, we report a promising ZIB cathode material based on electrochemically induced transformation of vanadium oxides. Specifically, K2V6O16·1.5H2O nanofibers were synthesized through a simple stirring method at near room temperature and then used as cathode materials for ZIBs in different electrolytes. The cathode presented superior Zn2+ storage capability in Zn(OTf)2 aqueous electrolyte, including high capacity of 321 mAh/g, fast charge/discharge ability (96 mAh/g delivered in 35 s), high energy density of 235 Wh/kg and good cycling performance. Mechanism analysis evidenced that in Zn(OTf)2 electrolyte, Zn2+ intercalation in the first discharge process promoted K2V6O16·1.5H2O nanofibers to transform into Zn3+xV2O7(OH)2·2H2O nanoflakes, and the latter served as the Zn2+-storage host in subsequent charge/discharge processes. Benefiting from open-framework crystal structure and sufficiently exposed surface, the Zn3+xV2O7(OH)2·2H2O nanoflakes exhibited high Zn2+ diffusion coefficient, smaller charge-transfer resistance and good reversibility of Zn2+ intercalation/de-intercalation, thus leading to superior electrochemical performance. While in ZnSO4 aqueous electrolyte, the cathode material cannot sufficiently transform into Zn3+xV2O7(OH)2·2H2O, thereby corresponding to inferior electrochemical behaviors. Underlying mechanism and influencing factors of such a transformation phenomenon was also explored. This work not only reports a high-performance ZIB cathode material based on electrochemically induced transformation of vanadium oxides, but also provides new insights into Zn2+-storage electrochemistry.
Rechargeable aqueous zinc-ion batteries have attracted extensive interest because of low cost and high safety. However, the relationship between structure change of cathode and the zinc ion storage ...mechanism is still complex and challenging. Herein, open-structured ferric vanadate (Fe2V4O13) has been developed as cathode material for aqueous zinc-ion batteries. Intriguingly, two zinc ion storage mechanism can be observed simultaneously for the Fe2V4O13 electrode, i.e., classical intercalation/deintercalation storage mechanism in the tunnel structure of Fe2V4O13, and reversible phase transformation from ferric vanadate to zinc vanadate, which is verified by combined studies using various in-situ and ex-situ techniques. As a result, the Fe2V4O13 cathode delivers a high discharge capacity of 380 mAh/g at 0.2 A/g, and stable cyclic performance up to 1000 cycles at 10 A/g in the operating window of 0.2–1.6 V with 2 mol/L Zn(CF3SO3)2 aqueous solution. Moreover, the assembled Fe2V4O13//Zn flexible quasi-solid-state battery also exhibits a relatively high mechanical strength and good cycling stability. The findings reveal a new perspective of zinc ion storage mechanism for Fe2V4O13, which may also be applicable to other vanadate cathodes, providing a new direction for the investigation and design of zinc-ion batteries.
Ferric vanadate (Fe2V4O13) is developed as cathode material for aqueous zinc-ion batteries. It combines two zinc ion storage mechanism: classical intercalation/deintercalation storage mechanism in the tunnel structure of Fe2V4O13, and reversible phase transformation from ferric vanadate to zinc vanadate. Display omitted
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