Stretchable, Weavable Coiled Carbon Nanotube/MnO2/Polymer Fiber Solid-State Supercapacitors

Abstract

Fiber and yarn supercapacitors that are elastomerically deformable without performance loss are sought for such applications as power sources for wearable electronics, micro-devices, and implantable medical devices. Previously reported yarn and fiber supercapacitors are expensive to fabricate, difficult to upscale, or non-stretchable, which limits possible use. The elastomeric electrodes of the present solid-state supercapacitors are made by using giant inserted twist to coil a nylon sewing thread that is helically wrapped with a carbon nanotube sheet, and then electrochemically depositing pseudocapacitive MnO2 nanofibers. These solid-state supercapacitors decrease capacitance by less than 15% when reversibly stretched by 150% in the fiber direction, and largely retain capacitance while being cyclically stretched during charge and discharge. The maximum linear and areal capacitances (based on active materials) and areal energy storage and power densities (based on overall supercapacitor dimensions) are high (5.4 mF/cm, 40.9 mF/cm2, 2.6 μWh/cm2 and 66.9 μW/cm2, respectively), despite the engineered superelasticity of the fiber supercapacitor. Retention of supercapacitor performance during large strain (50%) elastic deformation is demonstrated for supercapacitors incorporated into the wristband of a glove.

Improvement of system capacitance via weavable superelastic biscrolled yarn supercapacitors

“…In addition to providing high-density energy storage and fast energy release, these fibres must also be sufficiently robust to be fabricated into textiles by such industrial processes as weaving, knitting and sewing. Important recent advances have increased the energy and power densities of fibre-based supercapacitors123456789101112131415161718192021222324252627282930, some of which also provide high flexibility and stretchability. Yet, the ever advancing applications needs far eclipse presently realized power and energy densities of yarns and fibres and new approaches are needed to bridge this technology gap.…”

“…In this direction, recent improved fibre-based supercapacitors have used thin MnO 2 coatings that are applied to highly conductive and, in some cases, highly stretchable base fibres234567891011121314151617. Ultimately, however, this core–shell structure limits the allowable active material loading before performance is compromised.…”

“…The fundamental problem is that only the shell is utilized as an effective loading site for active materials, while the bulk core of the fibre does not participate in the electrochemical charge/discharge processes2. Active material loadings have to date been restricted to <20 wt%, even when nano-structured core fibres have been used, such as twist-spun carbon nanotube (CNT) yarns2456 and CNT-coated, coiled nylon fibre3.…”

Recent advances and challenges of stretchable supercapacitors based on carbon materials

“…8c). Additionally , Choi et al [114] used a nylon sewing thread that is helically wrapped with a carbon nanotube sheet, and then electrochemically depositing pseudocapacitive MnO 2 nanofibers to achieve the length, area and volume-normalized specific capacitances of 5.4 mF cm −1 , 40.9 mF cm −2 and 3.8 F cm −3…”

Nanomaterials for Stretchable Energy Storage and Conversion Devices

“…These excellent electrochemical and mechanical characteristics made the supercapacitor a promising energy storage device for smart textiles. Choi et al chose a commercial nylon fiber as the coiled polymer substrate [64]. When wrapped with CNT sheet and electrodeposited MnO 2 consequent consecutively (Fig.…”