THESIS
2019
xx, 164 pages : illustrations (some color) ; 30 cm
Abstract
All-solid-state supercapacitors possess high reliability, safety, leakage-free, and flexibility,
therefore have been recognized as one of the promising energy storage devices for next-generation
flexible/wearable electronic systems. However, the low ionic conductivities of
polymer solid electrolytes and the poor solid-solid electrolyte/electrode contacts lead to inferior
electrochemical performance. Moreover, the current trend in small size portable electronic
devices has strongly stimulated the miniaturization of power sources. Unluckily, most of the
reported microsupercapacitors (MSCs) are employed wet processes which are incompatible
with the standard Si-based IC industry, seriously limiting the miniaturizing process of on-chip
integration and the entire electronic systems....[
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All-solid-state supercapacitors possess high reliability, safety, leakage-free, and flexibility,
therefore have been recognized as one of the promising energy storage devices for next-generation
flexible/wearable electronic systems. However, the low ionic conductivities of
polymer solid electrolytes and the poor solid-solid electrolyte/electrode contacts lead to inferior
electrochemical performance. Moreover, the current trend in small size portable electronic
devices has strongly stimulated the miniaturization of power sources. Unluckily, most of the
reported microsupercapacitors (MSCs) are employed wet processes which are incompatible
with the standard Si-based IC industry, seriously limiting the miniaturizing process of on-chip
integration and the entire electronic systems.
In this thesis, we firstly propose large-sized anion BOB- acting as a solid plasticizer to improve the ionic conductivity of PVDF-HFP/LiBOB polymer solid electrolyte (PSE) up to
6×10
−5 S cm
−1, which is almost one order of magnitude higher than those of conventional solid
polymer electrolyte. Moreover, to enhance the interface contact of solid electrolyte/ electrode,
we successfully develop a novel electric-ionic polymer hybrid nanocomposite (EIHPN)
electrode by adopting the PVDF-HFP/LiBOB as both the host of capacitive materials graphene
oxide/carbon nanotube scaffold to form GO/CNT/PSE nanocomposite electrodes and separator
to form flexible solvent-free lithium-ion symmetric supercapacitors. The EIHPN electrode
could facilitate the access of ions to capacitive material surfaces and their monolithic integration
with PSE remarkably improves the electrode/electrolyte contacts, leading to high specific
capacitance (GO/CNT/PSE, 267 F g
-1) and energy density (30 Wh kg
-1).
In addition, we demonstrate an in-plane 3D Si/Ni nanoforest (SNNF) electrode based on-chip
MSC using COMS-compatible microfabrication processes. The SNNF electrodes
comprise of nickel-coated n-type poly-silicon interdigital-beams with monolithically integrated
silicon-nanopillars forest. Incorporating with solid-state PVDF-HFP/LiBOB based polymer
electrolyte, the produced all-solid-state on-chip MSCs exhibit excellent capacitive behavior
with a high device areal capacitance (0.53 mF cm
-2) and show a great advantage in inhibition
of leakage and encapsulation convenience over liquid electrolytes. Overall, these above
findings show that all-solid-state PVDF-HFP/LiBOB PSE based supercapacitors could benefit
a wide variety of energy storage applications.
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