Biocompatible, High‐Performance, Wet‐Adhesive, Stretchable All‐Hydrogel Supercapacitor Implant Based on PANI@rGO/Mxenes Electrode and Hydrogel Electrolyte

Abstract

Functional bioelectronic implants require energy storage units as power sources. Current energy storage implants face challenges of balancing factors including high‐performance, biocompatibility, conformal adhesion, and mechanical compatibility with soft tissues. An all‐hydrogel micro‐supercapacitor is presented that is lightweight, thin, stretchable, and wet‐adhesive with a high areal capacitance (45.62 F g−1) and energy density (333 μWh cm−2, 4.68 Wh kg−1). The all‐hydrogel micro‐supercapacitor is composed of polyaniline@reduced graphene oxide/Mxenes gel electrodes and a hydrogel electrolyte, with its interfaces robustly crosslinked, contributing to efficient and stable electrochemical performance. The in vitro and in vivo biocompatibility of the all‐hydrogel micro‐supercapacitor is evaluated by cardiomyocytes and mice models. The latter is systematically conducted by performing histological, immunostaining, and immunofluorescence analysis after adhering the all‐hydrogel micro‐supercapacitor implants onto hearts of mice for two weeks. These investigations offer promising energy storage modules for bioelectronics and shed light on future bio‐integration of electronic systems.

Diamond Supercapacitors: Towards Durable, Safe, and Biocompatible Aqueous-Based Energy Storage

“…Considering biological applications, the biocompatibility of diamond-composite PCs would partly depend on the properties of the non-diamond material. Of the established PC materials, conducting polymers are generally considered biocompatible, with PAni, PPy, and PEDOT:PSS being employed for supercapacitors in biological applications ( Sim et al, 2018 ; Liu et al, 2021 ; Ramanavicius and Ramanavicius, 2021 ). In addition, transition metal oxides such as MnO 2 and RuO 2 have exhibited good biocompatibility when the electrode is treated to prevent electrode degradation and ions being eluted into solution ( Chae et al, 2017 ; Wang et al, 2019 ; He et al, 2020 ; Shige Wang et al, 2020 ).…”

“…Moreover, diamond is stable in corrosive chemicals such as nitric or sulfuric acid ( Hoffmann et al, 2010 ), and is resistant to degradation through electrochemical oxidation in contrast to other sp 2 carbon materials ( Castanheira et al, 2014 ; Gao and Nebel, 2016 ). These properties suggest the use of diamond in surgically implantable supercapacitors, which are attractive power sources for biomedical devices due to high power density, long lifespan, and small dimensions ( Chae et al, 2017 ; Sim et al, 2018 ; Liu et al, 2021 ). Diamond-based supercapacitors are able to use safer aqueous electrolytes while retaining an extended potential window, or could possibly even use the physiological electrolyte itself, as has been done previously with other materials [see ( Chae et al, 2017 ; Raravikar et al, 2017 ; Sim et al, 2018 )].…”

Role of MXenes/Polyaniline Nanocomposites in Fabricating Innovative Supercapacitor Technology

“…Therefore, strategies to intimately blend three components in the appropriate extents to assure synergistic contributions through mutual synchronization of their benefits and setting aside individual shortcomings to accomplish utmost device efficacy [97]. Consequently, various ternary nanocomposites with PANI and MXenes as common components have been fabricated, as indicated in Table 5, showing diverse architectural and electronic features with fruitful outcomes not only in accomplishing larger capacitive performances due to the increased degree of redoxactive sites, preferential morphology for faster electrons/ions transfer kinetics, uncomplicated interfacial chemistries but also in enhancing mechanical features for manufacturing smarter electronic accessories [98][99][100][101][102]. Thus, MXene-CNT/ PANI ternary nanocomposite electrode was constructed with optimized composition by inserting PANI-coated CNTs in-between the MXene layers that synergistically supported improved electron and ion transfer processes for improved overall capacitive response, as illustrated in Figure 6(a) [98].…”

“…The resultant energy storage system was found to be air-light, miniatured and portable, besides being flexible, stretchable, and wet-adhesive in character. The designing strategy not only facilitated robust interfacial interactions among gel electrodes and gel electrolytes for securing large areal capacitance and energy density but also benefited the development of multifunctional bio-integrative electronics on wet tissues and vital body organ units with appreciable invitro and in-vivo biocompatibility [101]. Similarly, for better surface area accessibility and better ion insertion/extraction pathways, hierarchical PANI@ TiO 2 /Ti 3 C 2 T x ternary composite was fabricated by introducing PANI nanoflakes and TiO 2 nanoparticles in between MXene layers for improved pseudocapacitance and increased surface-active densities.…”

Redox and conductive underwater adhesive: an innovative electrode material for convenient construction of flexible and stretchable supercapacitors

“…To overcome this drawback, wrinkled polypyrrole (PPy) lms or polyaniline (PANI) exible hydrogels have been exploited as electrode materials to match the requirement of mechanical deformation. [15][16][17][18][19] In spite of these efforts, there is still a grand challenge needed to be tackled in the improvement of the reliable performance and lifetime of the resultant exible SCs. This challenge stems from the fact that repeated mechanical deformation usually causes inevitable displacement, separation or delamination between the electrode coatings and electrolytes or the current collectors suffering from poor adhesion.…”