Double-network
tough hydrogels have raised increasing interest
in stretchable electronic applications as well as electronic skin
(e-skin) owing to their excellent mechanical properties and functionalities.
While hydrogels have been extensively explored as solid-state electrolytes,
stretchable energy storage devices based on tough hydrogel electrolytes
are still limited despite their high stretchability and strength.
A key challenge remains in the robust electrode/electrolyte interface
under large mechanical strains. Inspired by the skin structure that
involves the microstructured interface for the tight connection between
the dermis and epidermis, we demonstrated that a surface-microstructured
tough hydrogel electrolyte composed of agar/polyacrylamide/LiCl (AG/PAAm/LiCl)
could be exploited to allow stretchable supercapacitors with enhanced
mechanical and electrochemical performance. The prestretched tough
hydrogel electrolyte was treated to generate surface microstructures
with a roughness of tens of micrometers simply via mechanical rubbing
followed by the attachment of activated carbon electrodes on both
sides to realize the fabrication of the stretchable supercapacitor.
Through investigating the properties of the tough hydrogel electrolyte
and the electrochemical performance of the as-fabricated supercapacitors
under varied strains, the surface-microstructured hydrogel electrolyte
was shown to enable robust adhesion to electrodes, improving electrochemical
behavior and capacitance, as well as having better performance retention
under repeated stretching cycles, which surpassed the pristine hydrogel
with smooth surfaces. Our approach could provide an alternative and
general strategy to improve the interfacial properties between the
electrode and the hydrogel electrolyte, driving new directions for
functional stretchable devices based on tough hydrogels.
Aqueous zinc‐ion batteries (ZIBs) have been extensively studied due to their inherent safety and high energy density for large‐scale energy storage. However, the practical application is significantly limited by the growing Zn dendrites on metallic Zn anode during cycling. Herein, an environmental biomolecular electrolyte additive, fibroin (FI), is proposed to guide the homogeneous Zn deposition and stabilize Zn anode. This work demonstrates that the FI molecules with abundant electron‐rich groups (NH, OH, and CO) can anchor on Zn anode surface to provide more nucleation sites and suppress the side reactions, and the strong interaction with water molecules can simultaneously regulate the Zn2+ coordination environment facilitating the uniform deposition of Zn. As a consequence, only 0.5 wt% FI additive enables a highly reversible Zn plating/stripping over 4000 h at 1 mA cm−2, indicating a sufficient advance in performance over state‐of‐the‐art Zn anodes. Furthermore, when applied to a full battery (NaVO/Zn), the cell exhibits excellent capacity retention of 98.4% after 1000 cycles as well as high Coulombic efficiency of 99%, whereas the cell only operates for 68 cycles without FI additive. This work offers a non‐toxic, low‐cost, effective additive strategy to solve dendrites problems and achieve long‐life and high‐performance rechargeable aqueous ZIBs.
We report the synthesis of a novel three-dimensional anode based on the core-shell Sn-Ni-Cu-alloy@carbon nanorods which was fabricated by pulse nanoelectrodeposition. Li ion batteries equipped with the three-dimensional anode demonstrated almost 100% capacity retention over 400 cycles at 450 mA g(-1) and excellent rate performance even up to 9000 mA g(-1) for advanced Li-ion battery. Insight of the high performance can be attributed to three key factors, Li-Sn alloys for Li-ion storage, Ni-Cu matrix for the electronic conductive and nanorods structure, and the carbon shell for the electronic/Li-ion conductive and holding stable solid electrolyte interphase (SEI), because these shells always kept stable volumes after extension of initial charge-discharge cycles.
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