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Abstract Rapidly growing flexible and wearable electronics highly demand the development of flexible energy storage devices. Yet, these devices are susceptible to extreme, repeated mechanical deformations under working circumstances. Herein, the design and fabrication of a smart, flexible Li‐ion battery with shape memory function, which has the ability to restore its shape against severe mechanical deformations, bending, twisting, rolling or elongation, is reported. The shape memory function is induced by the integration of a shape‐adjustable solid polymer electrolyte. This Li‐ion battery delivers a specific discharge capacity of≈140 mAh g‐1at 0.2 C charge/discharge rate with≈92% capacity retention after 100 cycles and≈99.85% Coulombic efficiency, at 20°C. Besides recovery from mechanical deformations, it is visually demonstrated that the shape of this smart battery can be programmed to adjust itself in response to an internal/external heat stimulus for task‐specific and advanced applications. Considering the vast range of available shape memory polymers with tunable chemistry, physical, and mechanical characteristics, this study offers a promising approach for engineering smart batteries responsive to unfavorable internal or external stimulus, with potential to have a broad impact on other energy storage technologies in different sizes and shapes.
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The effect of substrate curvature on capacitance and current–voltage characteristics in thin-film transistors on flexible substrates
Abstract Mechanically flexible electronics are devices designed to operate under significant physical deformations such as bending, twisting, and stretching. While the materials systems and devices compatible with flexible substrates have been extensively studied, the mathematical framework for analysis remains identical to that of traditional planar silicon-based electronics. However, the non-planar and dynamic form factors desired from flexible electronics invalidate assumptions made in these models. For electronic devices to be predictable and ultimately commercially viable, they must be understood in any physical form. Here we employ the method of moments to calculate the capacitance between two electrical conductors of arbitrary shape. Combined with a model for source–drain current in thin-film transistors (TFTs) on the surface of a cylinder, we are able to calculate the current–voltage characteristics in curved TFTs as a function of bending angle. We demonstrate how deformations to device geometry are expected to lead to non-negligible changes in current–voltage characteristics. This work represents the first step towards a new framework for understanding and characterizing electronics with any physical form factor, ultimately bringing flexible electronics closer to commercial viability.
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- Award ID(s):
- 1902032
- PAR ID:
- 10361217
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Journal of Physics: Materials
- Volume:
- 4
- Issue:
- 2
- ISSN:
- 2515-7639
- Page Range / eLocation ID:
- Article No. 025002
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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