A UV cross-linked gel polymer electrolyte enabling high-rate and high voltage window for quasi-solid-state supercapacitors

Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices,gel polymer electrolytes(GPEs)are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability.Here,an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation,in which N-doped carbon quantum dots(N-CQDs)and TiO2are introduced as photocatalysts and additives to improve the performances of GPEs.Specifically,N-CQDs participate as a cross-linker to construct the inner porous structure,and TiO2nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage(3.5 V).The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors(SCs).This GPE based SC not only exhibits prominent rate performance(105%capacitance retention at the current density of 40A g^(-1))and cyclic stability(85%at 1 A g^(-1)under 3.5 V after 20,000 cycles),but also displays remarkable energy density(42.88 Wh kg^(-1))with high power density(19.3 k W kg^(-1)).Moreover,the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.

Rational construction of phosphate layer to optimize Cu-regulated Fe_(3)O_(4) as anode material with promoted energy storage performance for rechargeable Ni-Fe batteries

Flexible aqueous energy storage devices with high security and flexibility are crucial for the progress of wearable energy storage.Particularly,aqueous rechargeable Ni-Fe batteries owning a large theoretical capacity,low cost and outstanding safety characteristics have emerged as a promising candidate for flexible aqueous energy storage devices.Herein,Cu-doped Fe_(3)O_(4)(CFO)with 3D coral structure was prepared by doping Cu^(2+) based on Fe_(3)O_(4)nanosheets(FO).Furthermore,the Fe-based anode material(CFPO)grown on carbon fibers was obtained by reconstructing the surface of CFO to form a low-crystallization shell which can enhance the ion transport.Excitingly,the newly developed CFPO electrode as an innovative anode material further exhibited a high capacity of 117.5 mAh g^(-1)(or 423 F g^(-1))at 1 A g^(-1).Then,the assembled aqueous Ni-Fe batteries with a high cell-voltage output of 1.6 V deliver a high capacity of 49.02 mAh g^(-1) at 1 A g^(-1) and retention ratio of 96.8%for capacitance after 10000 continuous cycles.What’s more,the aqueous quasi-solid-state batteries present a remarkable maximal energy density of 45.6 Wh kg^(-1) and a power density of 12 kW kg^(-1).This work provides an innovative and feasible way and optimization idea for the design of high-performance Fe-based anodes,and may promote the development of a new generation of flexible aqueous Ni-Fe batteries.