The Nail Penetration Behaviour of Carbon Nanotube Composite Electrodes for Energy Storage

Evangelos Koliolios,Wei Tan,Daniel G Mills,James J C Busfield

doi:10.3389/fmats.2021.741541

Evangelos Koliolios, Wei Tan + Show 2 more

Open Access

https://doi.org/10.3389/fmats.2021.741541

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Abstract

The high surface area, electrical and mechanical properties of carbon nanotube (CNT) composites has rendered them promising candidates for structural power composites. Nevertheless, it is important to understand their mechanical behaviour before they are applied in energy storage devices amid the safety concerns. This work explores the nail penetration behaviours of supercapacitor specimens consisting of CNT electrodes and pseudocapacitor specimens with carbon nanotube-polyaniline (CNT/PANI) electrodes. Specimens with and without electrolyte were tested. The dry cells without electrolyte follow a power law behaviour, while the wet cells with the electrolyte exhibit a piece-wise nonlinear relationship. The force, voltage and temperature of the supercapacitor were recorded during the nail penetration test. No temperature change or overheating was observed after short-circuit. Moreover, electrochemical testing is performed before and after the specimen penetration. The cyclic voltammetry shows the dramatic loss of capacitance, changing the cell behaviour from capacitor to resistor-like manner. Johnson-Cook model was used to predict the nail penetration behaviour. The coefficients of Johnson-Cook model are calibrated from the experimental load-displacement curves. The finite element model predictions are in a good agreement with the experimental results.

Highlights

Battery perforation and internal short circuiting is likely to occur in the event of a collision involving electric vehicles or hybrid vehicles
Regarding the safety standards of commercial supercapacitors, a review was conducted by Walden et al (2011) where nail penetration and overcharging for devices with supercapacitors were suggested as potential safety tests, which are similar to the tests conducted for commercial lithium-ion batteries
Prior to the puncture point, the stick-slip behaviour can be clearly seen in T3 of Figure 6A where there is force relaxation and subsequent increase, indicating the separator has yielded in the transverse direction (TD)

Summary

Introduction

Battery perforation and internal short circuiting is likely to occur in the event of a collision involving electric vehicles or hybrid vehicles. Nail penetration testing is one of the widely-used methods to evaluate the damage tolerance, internal short circuit behaviour and fire safety of lithium ion batteries. As the energy density of supercapacitors increases and their use becomes more widespread, understanding their failure behavior is critical to aid the proliferation of their use in efficient, low emission vehicles. Regarding the safety standards of commercial supercapacitors, a review was conducted by Walden et al (2011) where nail penetration and overcharging for devices with supercapacitors were suggested as potential safety tests, which are similar to the tests conducted for commercial lithium-ion batteries.

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