Flexible energy storage devices are at the forefront of next‐generation power supplies, one of the most important components of which is the gel electrolyte. However, shortcomings exist, more or ...less, for all the currently developed hydrogel electrolytes. Herein, a facile and cost‐effective method is developed to construct an all‐round hydrogel electrolyte by using cotton as the raw material, tetraethyl orthosilicate as the crosslinker, and glycerol as the antifreezing agent. The obtained hydrogel electrolyte has high ionic conductivity, excellent mechanical properties (e.g., high tensile strength and elasticity), ultralow freezing point, good self‐healing ability, high adhesion, and good heat‐resistance ability. Remarkably, this hydrogel electrolyte can provide a record‐breaking high ionic conductivity of 19.4 mS cm−1 at −40 °C compared with previously reported aqueous electrolytes for zinc‐ion batteries. In addition, this hydrogel electrolyte can significantly inhibit zinc dendritic growth and parasitic side reactions from −40 to 60 °C. With this hydrogel electrolyte, a flexible quasi‐solid‐state Zn–MnO2 battery is assembled, which shows remarkable energy densities from −40 to 60 °C. The battery also exhibits outstanding cycling durability and has high endurance under various harsh conditions. This work opens new opportunities for the development of hydrogel electrolytes.
A hydrogel electrolyte with high ionic conductivity, ultralow freezing point, excellent mechanical properties, good self‐healing ability, high adhesion, and good heat‐resistance ability is constructed. It can effectively suppress the growth of zinc dendrites and the occurrence of parasitic side reactions, thereby enabling a high‐performance flexible quasi‐solid‐state Zn–MnO2 battery that can work normally in a wide temperature range.
Flexible aqueous zinc-ion batteries (AZIBs) are promising to satisfy the emerging wearable electronics. However, conventional hydrogel electrolytes are unable to work at subzero temperatures because ...they inevitably freeze. In this work, a borax-crosslinked polyvinyl alcohol (PVA)/glycerol gel electrolyte is developed, in which glycerol can strongly interact with PVA chains, thus effectively prohibiting the formation of ice crystals within the whole gel network. Thanks to this, the freezing point of this gel electrolyte is below −60 °C, which allows it to work in extremely cold environments. Even at −35 °C, it still exhibits a high ionic conductivity of 10.1 mS cm−1 and great mechanical properties. On the basis of this anti-freezing gel electrolyte, a flexible quasi-solid-state aqueous Zn–MnO2 battery is assembled and realizes an impressive energy density of 46.8 mW h cm−3 (1330 μW h cm−2) at a power density of 96 mW cm−3 (2.7 mW cm−2) at 25 °C, outperforming nearly all the reported AZIBs. More importantly, when the temperature is reduced to −35 °C, a rather high energy density (25.8 mW h cm−3, 732 μW h cm−2) can still be achieved, and 53.3% of that value can be retained when the power density is increased to about 10-fold. This battery also shows excellent cycling durability (around 90% capacity retention over 2000 cycles) and great tolerance to various extreme conditions even when the temperature is down to −35 °C. These findings provide valuable insights into designing aqueous batteries/supercapacitors that can work in cold climates and high-altitude areas.
With the rapid development of wearable electronics, there arises an urgent need to exploit flexible, bendable, and even self-reparative energy storage devices. In order to realize this goal, one ...should construct suitable gel electrolytes. Herein, a zinc-salt-containing borax-crosslinked polyvinyl alcohol/nanocellulose hydrogel electrolyte is developed, and shows great mechanical properties, intriguing self-healing feature, and high ionic conductivity. To demonstrate the feasibility of this hydrogel electrolyte, a flexible quasi-solid-state zinc-ion hybrid supercapacitor is assembled from the hydrogel electrolyte, cellulose paper cathode, and zinc metal anode. This device can combine the advantages of both zinc-ion batteries and supercapacitors. It exhibits high capacity (56.1 mA h g
−1
, 504.9 mF cm
−2
, and 224.4 μA h cm
−2
at 0.5 mA cm
−2
), great rate capability (22.1 mA h g
−1
at 10 mA cm
−2
), and excellent cyclability (95.3% capacity retention over 5000 cycles). It can also be folded, bent, compressed, and even self-healed while sacrificing only a small portion of its capacity. This work opens the door to new possibilities in flexible energy storage.
The quasi-solid-state zinc-ion hybrid supercapacitor based on borax-crosslinked polyvinyl alcohol/nanocellulose hydrogel electrolyte displays not only great electrochemical performances but also high flexibility and self-healing ability.
Laser‐induced graphene (LIG) has emerged as a promising and versatile method for high‐throughput graphene patterning; however, its full potential in creating complex structures and devices for ...practical applications is yet to be explored. In this study, an in‐situ growing LIG process that enables to pattern superhydrophobic fluorine‐doped graphene on fluorinated ethylene propylene (FEP)‐coated polyimide (PI) is demonstrated. This method leverages on distinct spectral responses of FEP and PI during laser excitation to generate the environment preferentially for LIG formation, eliminating the need for multistep processes and specific atmospheres. The structured and water‐repellant structures rendered by the spectral‐tuned interfacial LIG process are suitable as the electrode for the construction of a flexible droplet‐based electricity generator (DEG), which exhibits high power conversion efficiency, generating a peak power density of 47.5 W m−2 from the impact of a water droplet 105 µL from a height of 25 cm. Importantly, the device exhibits superior cyclability and operational stability under high humidity and various pH conditions. The facile process developed can be extended to realize various functional devices.
Monolithic fabrication of a flexible droplet‐based electricity generator (DEG) is demonstrated by in situ growth of laser‐induced graphene electrodes with different hydrophobicity in a fluorinated ethylene propylene‐coated polyimide bilayer structure. The DEG exhibits high power conversion efficiency, lighting up 480 LEDs with one water droplet. More importantly, the DEG exhibits superior cyclability and operational stability under high humidity and various pH conditions.
Photodynamic therapy (PDT) typically involves oxygen (O2) consumption and therefore suffers from greatly limited anticancer therapeutic efficacy in tumor hypoxia. Here, it is reported for the first ...time that amine‐terminated, PAMAM dendrimer‐encapsulated gold nanoclusters (AuNCs‐NH2) can produce O2 for PDT via their intrinsic catalase‐like activity. The AuNCs‐NH2 not only show optimum H2O2 consumption via the catalase‐like activity over the physiological pH range (i.e., pH 4.8–7.4), but also extend such activity to acidic conditions. The possible mechanism is deduced from that the enriched tertiary amines of dendrimers are easily protonated in acidic solutions to facilitate the preadsorption of OH on the metal surface, thereby favorably triggering the catalase‐like reaction. By taking advantage of the exciting feature on AuNCs‐NH2, the possibility to supply O2 via the catalase‐like activity of AuNCs‐NH2 for PDT against hypoxia of cancer cells was further studied. This proof‐of‐concept study provides a simple way to combine current O2‐dependent cancer therapy of PDT to overcome cancer cell hypoxia, thus achieving more effective anticancer treatments.
PAMAM dendrimer‐encapsulated gold nanoclusters (AuNCs‐NH2) exhibit their catalase‐like activity over a pH range relevant to biological microenvironments (i.e., pH 4.8–7.4), such that AuNCs‐NH2 can catalyze physiological hydrogen peroxide (H2O2) to produce O2 that self‐supplies for photodynamic therapy against hypoxic cancer cells.
Despite great prospects, Zn//MnO2 batteries suffer from rampant and vertical deposition of zinc sulfate hydroxide (ZSH) at the cathode surface, which leads to a significant impact on their ...electrochemical performance. This phenomenon is primarily due to the drastic increase in the electrolyte pH value upon discharging, which is closely associated with the electrodissolution of Mn‐based active materials. Herein, the pH value change is effectively inhibited by employing an electrolyte additive with excellent pH buffering capability. As such, the formation of ZSH at the cathode is postponed, resulting in the deposition of ZSH in a horizontal arrangement. This strategy can significantly enhance the utilization efficiency of cathode active material, while also enabling a solid electrolyte interphase layer at the Zn anode to address low Zn stripping/plating reversibility. With the optimal electrolyte, the Zn//MnO2 battery realizes a 25.6% increase in the specific capacity at 0.2 A g−1 compared to that with the baseline electrolyte, great rate capability (161.6 mAh g−1 at 5 A g−1), and superior capacity retention (90.2% over 5,000 cycles). In addition, the pH buffering strategy is highly applicable in hydrogel electrolytes. This work underscores the importance of pH regulation for Zn//MnO2 batteries and provides enlightening insights.
In order to mitigate the detrimental effects of dramatic pH increases in Zn//MnO2 batteries upon discharging due to the electrodissolution of MnO2, an electrolyte additive with exceptional pH buffering capability has been introduced. This can effectively suppress rampant and vertical deposition of zinc hydroxide sulfate intermediate product at the cathode, thereby significantly improving the electrochemical performance of Zn//MnO2 batteries.
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•Ti3C2Tx flakes are modified by alkalization and post-annealing treatments.•Most of –F and –OH functional groups in the Ti3C2Tx can be removed.•The modified Ti3C2Tx is combined with ...nanocellulose extracted from soybean stalks.•The composite film exhibits high tensile strength and large electrical conductivity.•Great performance is achieved for both supercapacitors and zinc ion capacitors.
Ti3C2Tx is a promising electrode material for supercapacitors, whereas it suffers from the re-stacking problem and fluorine-rich functional groups, thereby restricting its electrochemical performance. Herein, delaminated Ti3C2Tx flakes are modified by alkalization and post-annealing treatments to considerably decrease –F and –OH functional groups. In addition, inspired by the architecture of nacres, the modified Ti3C2Tx is combined with soybean stalk-derived nanofibrillated cellulose, which can improve mechanical properties, prevent dense packing of Ti3C2Tx, and facilitate the transport of electrolyte ions. Therefore, the optimized composite film exhibits large tensile strength (53.9 MPa), high electrical conductivity (24930 S m−1), and superior electrochemical performance for supercapacitors and zinc-ion capacitors. In particular, the composite film under quasi-solid-state supercapacitor configuration delivers high capacitances of 303.1 and 211.4 F g−1 at 1 and 10 mA cm−2, respectively, excellent cyclability (92.84% capacitance retention over 10,000 cycles), and great affordability to bending deformations. This work offers an efficient way to construct high-performance flexible electrodes for high-power applications.
Molybdenum disulfide (MoS2) nanosheets have been attracting increasing research interests due to their unique material properties. However, the lack of a reliable large‐scale production method ...impedes their practical applications. Here a facile, efficient, and scalable method for the fabrication of high‐concentration aqueous dispersion of MoS2 nanosheets using combined grinding and sonication is reported. The 26.7 ± 0.7 mg/mL concentration achieved is the highest concentration in an aqueous solution reported up to now. Grinding generates pure shear forces to detach the MoS2 layers from the bulk materials. Subsequent sonication further breaks larger crystallites into smaller crystallites, which promotes the dispersion of MoS2 nanosheets in ethanol/water solutions. The exfoliation process establishes a new paradigm in the top‐down fabrication of 2D nanosheets in aqueous solution. In the meantime, MoS2‐based sensing film produced using this approach has successfully demonstrated the feasibility of a low‐cost and efficient NH3 gas sensor using inkjet printing as a viable method.
The lack of a reliable large‐scale production method inhibits practical applications of MoS2 nanosheets. To address this, a facile, efficient, and scalable method for the fabrication of high‐concentration aqueous dispersion of MoS2 nanosheets using combined grinding and sonication is developed. The exfoliation process establishes a new paradigm in the top‐down fabrication of 2D nanosheets in aqueous solution.
Aqueous zinc-ion batteries (AZIBs) are promising due to their intrinsic safety and low cost. However, the unsatisfactory cathode materials with low mass loading (<3 mg cm
−2
) and high freezing point ...of aqueous electrolytes severely limit the application prospects of AZIBs. Herein, Mg
0.19
V
2
O
5
·0.99H
2
O (δ-MgVO) with a large interlayer spacing of 13.4 Å is synthesized through a facile pre-intercalation strategy, and is used to construct a cathode with a commercial-level mass loading of 10 mg cm
−2
. At such a high mass loading, the δ-MgVO shows reversible charge storage behavior, high Zn
2+
ion diffusion coefficients, and fast electrochemical kinetics. Moreover, a quasi-solid-state battery is assembled by combining the δ-MgVO cathode with polyvinyl alcohol/glycerol gel electrolyte, which shows high ionic conductivity in a wide temperature range (
e.g.
, 10.7 mS cm
−1
at −30 °C) and excellent compatibility with a Zn foil anode. Thanks to that, the quasi-solid-state battery exhibits great performances from −30 to 60 °C. Remarkably, at a rather low temperature of −30 °C, an admirable energy density of 48.14 mW h cm
−3
(1940 μW h cm
−2
) can be achieved at 17.83 mW cm
−3
(0.72 mW cm
−2
). Overall, this work opens new opportunities for developing environmentally adaptive aqueous energy storage devices towards practical applications.
A quasi-solid-state zinc-ion battery exhibits remarkable areal and volumetric energy/power densities and excellent cyclability from −30 to 60 °C.
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