Nanocellulose-based Battery Electrodes

Abstract

Modern wearable electronic devices are limited by the development of power sources that are mechanically flexible and safe at the same time. The development of flexible Li-ion batteries has been demonstrated; however, the remaining challenges include the re-design of all battery components in order to make each one flexible. Graphite electrodes are the most widely used anodes in Li-ion batteries, but their conventional structure suffers from rigidity and brittleness. Here, nanocellulose which is a natural biopolymer, is integrated with graphite and is used as component for the fabrication of inherently flexible electrodes, that also address battery sustainability concerns.

In this work, flexible nanocellulose/graphite electrodes are manufactured, and their mechanical and electrochemical performance characteristics are examined via SEM, AFM, CV and EIS in Li-ion environment. The electrode can undergo a deformation of a 180o bending angle, trading-off 1/3 of conductivity. It is also shown that nanocellulose not only works as a flexible additive, but it can also promote ion mass transport, enabling ion access from the electrolyte, even to the bulk of the graphite electrode with reduced diffusion limitations. Parameters like nanocellulose content and nanoarchitecture are also correlated with fluctuations in ion mass transport. Molecular interactions between Li-ions and nanocellulose are examined by solid state NMR.

Wearable devices where safety is of crucial importance would potentially benefit more by the implementation of beyond Li-ion technologies, like aluminum-graphite batteries which are inherently safe. In this case, nanocellulose/graphite electrodes are also tested in the Al-ion battery chemistry and are proven to improve mass transport properties by 17%. This demonstrates the versatility of nanocellulose in different battery chemistries.

This work offers a perspective on the material-driven design of flexible nanocellulose/graphite electrodes, by investigating the contribution of nanocellulose to charge storage mechanisms and mechanical resilience, aligning with modern energy storage requisites. The use of nanocellulose/graphite electrodes in both Li-ion and Al-ion systems paves the way towards the diversification of the battery market.

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Identifiers

ORCID for Evangelia Founta: orcid.org/0000-0001-6459-8417

ORCID for Dimitra Georgiadou: orcid.org/0000-0002-2620-3346

ORCID for Carlos Ponce De Leon Albarran: orcid.org/0000-0002-1907-5913

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