Indenter for Pouch Cell Battery Safety Testing

Overview

Lithium-ion pouch cells come in small packages but can provide significant output for all kinds of products. Too often, though, damaging these cells can lead to disaster in the form of fires and explosions. Particularly in the world of electronic vehicles, even minor unchecked damage can lead to excessive heating and ignition during charging, which often happens inside the garage. From electric cars to hobby drones and from jump starters to military technology, batteries play an important role in powering humanity. In this project, we shine the spotlight on lithium-ion pouch cells in the pursuit of learning how to make such an incredible tool safer.

Objectives

– Design a mechanism to indent lithium-ion pouch cells with the following characteristics:

– Can create indentations at depths from 100 microns to a few millimeters

– Make indentations accurately measurable to 10 microns

– Prevent damage to any other part of the battery aside from the indentation

– Provide for multiple indentation sizes and shapes

– Operable by a handwheel

Approach

– Investigated past research on damage testing of lithium-ion pouch cells to understand their mechanical properties

– Researched existing products that could be potential solutions

– Designed several possible solutions based on existing products and new ideas

– Chose to purchase an arbor press and modify it with a gear system and high-accuracy dial gauge so it could apply forces high enough to indent the batteries, but also do it slow enough to measure displacements to 10 microns

– Create several steel indenter tips that would serve as the point of contact against the batteries

Outcomes

– Testing on brass and wood using a 2 mm and 8 mm diameter spherical-ended tip resulted in successful indentation that was measurable to 10 microns

– All components of the mechanism were able to survive full force testing