Session: 03-13-03: Manufacturing: General III

Paper Number: 166628

Solution Synthesis of Coaxial Nanostructure of Pedot/mno2/cnt for Flexibal and Minaturue Zn-Ion Batteery for Powering Bioelectronics 

Over the past decades, various wearable and implantable miniaturized bioelectronics have been designed and manufactured for monitoring, diagnosing, and treating human health and disease. The rapidly growing wearable and implantable electronics market creates a high demand for micro-size flexible energy storage devices (less than 1 cm² in footprint area). Batteries are considered the best power supply because of their high energy density, safety, and stability. Conventional miniature batteries are typically available in either cable or buck (sandwich) types. However, those micro batteries are usually made of rigid and bulky materials, which can lead to defects and even irreversible deformation that may act as active sites promoting the dendrite growth under the dynamic in-body environment. Some miniature batteries even contain corrosive and toxic components such as organic electrolytes, making them ineligible as power supplies for bioelectronics. In addition, the cathode and anode are generally just a few microns thick for most flexible batteries, and a separator is typically used to prevent direct electrode contact. Nevertheless, the growth of zinc dendrites can penetrate the separator, leading to internal short circuits. Most importantly, current batteries suffer significant oversize and mechanical mismatch challenges because of the sandwich and cable structure and Young’s moduli difference between tissues and batteries. Therefore, selecting the optimal battery configuration to ensure performance and miniaturization is a subject that requires thorough investigation. The planar battery design, known for integrating electrodes and electrolytes on the same plane, has been demonstrated to be a viable option since the planar configuration facilitates rapid ion transport along planar channels in the two-dimensional plane, even when subjected to significant bending. Simultaneously, the distinct planar design helps reduce the battery failure resulting from short circuits by the dendrite formation.

In addition, micro batteries' energy density and capacity remain unsatisfactory. Ye et al. reported an all-hydrogel lithium-ion battery based on polyacrylamide (PAM)/carbon nanotubes (CNTs) hydrogel electrodes and PAM hydrogel electrolytes. Despite the battery exhibiting a tissue-like Young’s modulus of around 80 kPa, it can only achieve a specific 82 mAh/g capacity at a current density of 0.5 A/g. Zhao et al. explored a fiber-shaped implantable battery using CNT/MoO₃/polypyrrole (PPy) and CNT/sodium manganese oxide (NMO) hybrid fiber electrodes with a PVA gel electrolyte. Although the injectable battery concept was demonstrated, it can deliver a power density of only 78.9 mW/cm³ in vivo. Zinc-ion batteries (ZIBs) have garnered increasing attention due to their high energy density, safety, low cost, and abundant zinc in natural resources. Among various cathode materials for ZIBs, MnO₂ is particularly popular because of its high theoretical capacity (616 mAh/g), low cost, wide availability, and nontoxicity. However, low electrical conductivity (10^-7 to 10^-8 S/cm), volume expansion, and limited ion diffusion caused by a paucity of free electrons and holes lead to a low capacity, poor rate performance, and weak stability of the MnO₂ material.

To address these challenges, coaxial PEDOT/MnO₂/CNTs nanostructure cathodes were synthesized to incorporate wide electrochemical stability window (ESW) ionogels for creating quasi-solid-state flexible ZIB. The coaxial nanostructure hindered manganese dissolution, enhanced conductivity, and improved ion diffusion, achieving a capacitance of 239.6 mAh/g at 1.0 A/g and 95% retention after 500 cycles (versus 56% retention for state-of-the-art). The coaxial nanostructure electrodes/ionogel electrolyte-based batteries demonstrated ESW as high as 2.79V, 54% higher than the current 1.81V for state-of-the-art, leading to an energy density as high as 573 Wh/kg—three times higher than state of the art. The battery maintained >94% performance under cyclic bending (0–180°). In vitro tests confirmed excellent biocompatibility with nearly 100% cell viability, making it a promising solution for bioelectronic applications.

Presenting Author: Shiren Wang Texas A&M University

Presenting Author Biography: Dr. Wang is a professor in the Department of Industrial and Systems Engineering, with joint appointment appointments at the Department of Materials Science and Engineering and the Department of Biomedical Engineering, Texas A&M University. His research is focused on advanced manufacturing and soft electronics.

Authors:

Chonjie Gao texas a&m university
Jenny Qiu Texas A&M University
Shiren Wang Texas A&M University