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 MnO 2 nanosheet cathode, and Zn 2+ -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.
Hydrogels, as a new type of biomaterial
with unique physical and
chemical characteristics, have three-dimensional solid networks constructed
by hydrophilic polymer chains. The superior swell-ability, biocompatibility,
and functionalization have made them widely explored and applied in
the removal of heavy metals from water. Due to the potential threats
of heavy metals, most wastewater systems control industrial discharges
at a multiple (e.g., 100 times higher) of the maximum contaminated
levels of heavy metals in drinking water. Nevertheless, how to employ
the hydrogel adsorbent fabricated in the lab for expanded applications
in real wastewater treatment is still a critical challenge. In this
review, we scrutinize and emphasize the latest developments in the
synthesis and application of hydrogels in removing and recycling heavy
metals from water. In particular, the barriers restraining development
and scale-up applications are presented, accompanied by the corresponding
solutions raised by our point of view. A detailed review is started
from the typical synthesis of hydrogels. Afterward, the innovative
and representative strategies with computer-aided design for synthesizing
hydrogels with the desired capacities are discussed and evaluated.
Challenges in perfecting the hydrogels with outstanding properties
in improving the anti-interference capability, accelerating the adsorption
rate, broadening the operational pH range, enhancing the selectivity,
and minimizing the toxicity are clarified. In addition, the mechanical
strength, resource recovery, and reusability of the hydrogels as well
as reasonable mass transfer models for adsorber design are used in
engineering applications. We also shed light on further improving
the features of the expected hydrogels.
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