Imaging: Using Neutron and X-ray Imaging to Improve Commercial off the Shelf Batteries

Starting in 2013 the Army Research Laboratory (ARL) along with the University of Maryland (UMD) College Park formed a battery research center that was later named the Center for Research on Extreme Batteries (CREB). Currently CREB is actively working on research projects funded through a grant from ARL. As part of this effort UMD researchers will work with the NIST Neutron Imaging Team working to develop battery imaging and analysis tools using neutrons. CREB is currently focused on advancing battery technology for the U.S. Army. NIST’s Neutron and X-ray Tomography (NeXT) system exploits the complementarity of the interactions of neutrons and X-rays with matter to enable clear identification of the electrochemical processes that are active in the battery to help solve existing safety and lifetime problems with lithium-ion batteries.

The NIST Neutron Imaging Facility (NNIF) has developed an in situ simultaneous Neutron and X-ray Tomography (NeXT) capability that allows for 3D imaging of batteries and other objects [1-3]. Neutrons are complementary to X-rays and when combined allow one to segment and identify features to non-destructively track the time evolution of a battery to the point of failure under the extreme environmental conditions that soldiers will find in the field as we see in Figure 1. Due to the large absorption cross-section of the isotope lithium-6, neutrons can detect concentrations and plating of lithium. Specially designed environmental chambers can simulate real world field conditions as both neutrons and X-rays can penetrate through the chamber windows to image a battery being cycled. In addition to sensitivity to lithium neutrons are also able to image hydrogenous materials in the presence of metals as well.

Neutron imaging can follow lithium plating during charge/discharge cycling [4-7]. This capability has been demonstrated by Siegel et al [4] to image both the concentration gradient of lithium in a pouch cell and formation of dendritic lithium as well. Owejan et al [5] have also demonstrated the detection and spatial uniformity of lithium consumed by the solid electrolyte interphase (SEI) during preconditioning. In-operando, non-destructive detection of Li plating in commercial off the shelf (COTS) batteries is of high importance for understanding performance degradation of Li-ion batteries during fast-charging or charging at low temperatures. The use of COTS cylindrical cells provides insight into behavior of batteries currently used by the Army. Pouch and coin cells can be used for electrolyte screening studies. The NIST NeXT setup will assess long term stability of new battery chemistries and designs as well. By using environmental platforms that have fiducial markers built in, it is possible to dismount batteries from the sample platform to continue long term cycling under a variety of conditions. Then the battery platform can be periodically remounted in the NeXT apparatus to image the battery at the point in time. Through the fiducial markers it is possible to correlate previous and future data sets in time. In this way one can follow the long-term degradation process in an optimized way, adding morphology information to the electrochemical markers of the battery degradation processes.

In this CREB project, NIST will systematically evaluate morphological changes that occur in the battery leading up to a thermal runaway event. This can allow battery designers better insight into how to engineer safeguards to prevent or mitigate these conditions. We will develop optimized data acquisition procedures to acquire 3D tomographic volumes in time for each area of interest in the proposal. NIST will also develop/engineer low and high temperature environmental chambers with containment systems for destructive testing. In addition to developing general use capabilities, the NIST effort will also develop and carry out testing methods towards using neutrons to improve the design of batteries using new water-in-salt electrolyte battery chemistries that are less likely to catch on fire and are therefore safer [8].

References

[1] J. M. Lamanna, D. S. Hussey, E. Baltic, and D. L. Jacobson, “Neutron and X-ray Tomography (NeXT) system for simultaneous, dual modality tomography,” Rev. Sci. Instrum., vol. 88, no. 11, p. 113702, Nov. 2017, doi: 10.1063/1.4989642.

[2] J. M. LaManna, D. S. Hussey, V. H. DiStefano, E. Baltic, D. L. Jacobson. NIST NeXT: a system for truly simultaneous neutron and X-ray tomography. In: Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXII, edited by Fiederle M, Burger A, Payne SA. SPIE, p. 24., doi: 10.1117/12.2569666.

[3] G. V. Riley, D. S. Hussey, and D. Jacobson, “In Situ Neutron Imaging of Alkaline and Lithium Batteries,” Apr. 2010, pp. 75–83, doi: 10.1149/1.3414005.

[4] J. B. Siegel, X. Lin, A. G. Stefanopoulou, D. S. Hussey, D. L. Jacobson, and D. Gorsich, “Neutron imaging of lithium concentration in LFP Pouch cell battery,” J. Electrochem. Soc., vol. 158, no. 5, 2011, doi: 10.1149/1.3566341.

[5] J. P. Owejan, J. J. Gagliardo, S. J. Harris, H. Wang, D. S. Hussey, and D. L. Jacobson, “Direct measurement of lithium transport in graphite electrodes using neutrons,” Electrochim. Acta, vol. 66, pp. 94–99, Apr. 2012, doi: 10.1016/j.electacta.2012.01.047.

[6] C. Cai, Z. Nie, J. P. Robinson, D. S. Hussey, J. M. LaManna, D. L. Jacobson, G. M. Koenig. "Thick Sintered Electrode Lithium-Ion Battery Discharge Simulations: Incorporating Lithiation-Dependent Electronic Conductivity and Lithiation Gradient Due to Charge Cycle," J Electrochem Soc 167: 140542, 2020, doi:10.1149/1945-7111/abc747.

[7] Z. Nie, S. Ong, D. S. Hussey, J. M. Lamanna, D. L. Jacobson, G. M. Koenig. Probing transport limitations in thick sintered battery electrodes with neutron imaging. Mol Syst Des Eng 5: 245–256, 2020, doi:10.1039/c9me00084d.

[8] Suo L, Borodin O, Gao T, Olguin M, Ho J, Fan X, Luo C, Wang C, Xu K. “Water-in-salt” electrolyte enables high-voltage aqueous lithium-ion chemistries. Science, vol. 350, 6263, pp. 938–943, 2015. DOI:10.1126/science.aab1595.