Nail Test

The nail test was originally designed to replicate a cell failure caused by a piece of rogue metal that gets into the cell during production. The metal nail causes a short circuit between the active layers and hence rapid electrical heating. This is one of the most severe cell tests and part of a suite of abuse tests.

Billy Wu when batteries go wrong
What happens when batteries are abused?

Lithium-ion batteries are an essential component in electric vehicles, however their safety remains a key challenge. This video explores the science behind what happens when batteries are abused and when they fail. A great introductory presentation by Billy Wu, Dyson School of Engineering, Imperial College.

It is notoriously difficult to get repeatable results with the nail penetration test.

The nail penetration test is one method of triggering thermal runaway in a cell. Thermal runaway propagation within cells is generally highest for nail penetration [4].

In a paper from Yuqing Chen et al [2] they have a table of test standards and this shows the variations in the nail test.

We know there is a lot of test to test variation and differences between standards.

Anand N. P. Radhakrishnan [3] show data processing techniques for the extraction of more data from these tests.

The following image is from a BYD and shows an image of the nail above the Blade cell and then on the right with the nail through the cell.

BYD nail penetration test of their blade cell

References

  1. Xiang Gao, Yikai Jia, Wenquan Lu, Qingliu Wu, Xinyu Huang, Jun Xu, Mechanistic understanding of reproducibility in nail penetration tests, Cell Reports Physical Science, Volume 4, Issue 9, 2023
  2. Yuqing Chen, Yuqiong Kang, Yun Zhao, Li Wang, Jilei Liu, Yanxi Li, Zheng Liang, Xiangming He, Xing Li, Naser Tavajohi, Baohua Li, A review of lithium-ion battery safety concerns: The issues, strategies, and testing standards, Journal of Energy Chemistry, Volume 59, 2021
  3. Anand N. P. Radhakrishnan, Mark Buckwell, Martin Pham, Donal P. Finegan, Alexander Rack, Gareth Hinds, Dan J. L. Brett and Paul R. Shearing, Quantitative spatio temporal mapping of thermal runaway propagation rates in lithium-ion cells using cross-correlated Gabor filtering, Energy& Environmental Science, Royal Society of Chemistry
  4. Matthew Sharp, John Jacob Darst, Peter Hughes, Julia Billman, Martin Pham, David Petrushenko, Thomas M. M. Heenan, Rhodri Jervis, Rhodri Owen, Drasti Patel, Du Wenjia, Harry Michael, Alexander Rack, Oxana V. Magdysyuk, Thomas Connolley, Dan J. L. Brett, Gareth Hinds, Matt Keyser, Eric Darcy, Paul R.Shearing, William Walker and Donal P. Finegan, Thermal Runaway of Li-Ion Cells: How Internal Dynamics, Mass Ejection, and Heat Vary with Cell Geometry and Abuse Type, Journal of The Electrochemical Society