Conductive Cellulose Composites with Low Percolation Threshold for 3D Printed Electronics

Jae Sung Park,Woo Soo Kim,Taeil Kim

doi:10.1038/s41598-017-03365-w

Abstract

We are reporting a 3D printable composite paste having strong thixotropic rheology. The composite has been designed and investigated with highly conductive silver nanowires. The optimized electrical percolation threshold from both simulation and experiment is shown from 0.7 vol. % of silver nanowires which is significantly lower than other composites using conductive nano-materials. Reliable conductivity of 1.19 × 102 S/cm has been achieved from the demonstrated 3D printable composite with 1.9 vol. % loading of silver nanowires. Utilizing the high conductivity of the printable composites, 3D printing of designed battery electrode pastes is demonstrated. Rheology study shows superior printability of the electrode pastes aided by the cellulose’s strong thixotropic rheology. The designed anode, electrolyte, and cathode pastes are sequentially printed to form a three-layered lithium battery for the demonstration of a charging profile. This study opens opportunities of 3D printable conductive materials to create printed electronics with the next generation additive manufacturing process.

Highlights

A sodium carboxymethyl cellulose (CMC) is often used and researched as a matrix material due to its viscosity thickening capability and thixotropic rheology[12,13,14]
Rheology study of the paste is carried out to observe thixotropism which is essential for 3D printable paste[20, 21]
The electrical percolation threshold is firstly investigated by computational simulation with the AgNW filled CMC based 3D Conductor

Summary

Introduction

A sodium carboxymethyl cellulose (CMC) is often used and researched as a matrix material due to its viscosity thickening capability and thixotropic rheology[12,13,14]. It has been drawing attentions for its water processability and proposed as a replacement material for conventional polymeric binders such as polyvinylidene fluoride (PVDF) which require the use of toxic solvents for their manufacturing[15,16,17]. Merging conductive AgNW filler with the CMC matrix can create a 3D Conductor

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