Fully Packaged Carbon Nanotube Supercapacitors by Direct Ink Writing on Flexible Substrates

Abstract

The ability to print fully packaged integrated energy storage components (e.g., supercapacitors) is of critical importance for practical applications of printed electronics. Due to the limited variety of printable materials, most studies on printed supercapacitors focus on printing the electrode materials but rarely the full-packaged cell. This work presents for the first time the printing of a fully packaged single-wall carbon nanotube-based supercapacitor with direct ink writing (DIW) technology. Enabled by the developed ink formula, DIW setup, and cell architecture, the whole printing process is mask free, transfer free, and alignment free with precise and repeatable control on the spatial distribution of all constituent materials. Studies on cell design show that a wider electrode pattern and narrower gap distance between electrodes lead to higher specific capacitance. The as-printed fully packaged supercapacitors have energy and power performances that are among the best in recently reported planar carbon-based supercapacitors that are only partially printed or nonprinted.

Direct Ink Writing of Wearable Thermoresponsive Supercapacitors with rGO/CNT Composite Electrodes

“…It is also more likely to cause tip clogging issue due to the carbon‐based material agglomeration. In comparison, the printing resolution of the electrodes in this study is characterized to be 175 ± 25 µm, which is among the best in the recently reported planar carbon‐based energy storage devices fabricated by DIW technique . The superior printability is beneficial from strong shear‐thinning behaviors and moderate viscosities of the inks prepared in this study.…”

“…The pattern is inspired by conventional supercapacitor interdigital structures, which are suitable for both sensing and wearable energy storage device applications (The dimensions are shown in Figure S2 in the Supporting Information) . The DIW printing resolution of carbon‐based materials in recently reported literature is in the range of 0.5–2.0 mm . To maintain the maximum pristine carbon material properties for high energy performance, many carbon material based inks used in the DIW process are free of binders, which results in poor dispersion of carbon‐based materials in a watery mixture .…”

“…The shear‐thinning property of our rGO/CNT ink allows a stable extrusion from the dispensing tip without clogging, and its moderate viscosity provides an equilibrium contact angle in the range of 50–70°, which makes it possible to fabricate fine features using DIW. After evaporating water contents in the printed rGO/CNT layer, acids are printed on the dried rGO/CNT layer, to remove the impurities and surfactants remained in it . The acids are deposited in a dot‐by‐dot way, instead of a continuous trace, to avoid the common bulge problem due to its low viscosity (1.2 mPa s at room temperature) .…”

3D printing of conjugated polymers

“…Using this ink and processing method, interdigitated planar supercapacitor was created with a H 2 SO 4 /poly(vinyl alcohol) gel electrolyte. The supercapacitor has an areal specific capacitance of 1255 ± 74 mF cm −2 at a current density of 4.2 ± 0.8 mA cm −2 , much higher than other supercapacitors prepared via DIW …”

“…The supercapacitor has an areal specific capacitance of 1255 AE 74 mF cm −2 at a current density of 4.2 AE 0.8 mA cm −2 , much higher than other supercapacitors prepared via DIW. [47][48][49] PSS paste with a suitably high initial viscosity and shearthinning behavior is first developed. Utilizing a pneumatic syringe, the authors printed lines of PEDOT:PSS and investigated the influence of two different substrates, glass and a hydrogel made of chitosan and hyaluronic acid, on the electrical properties of the extruded material.…”