Extreme Fast Charge Challenges for Lithium-Ion Battery: Variability and Positive Electrode Issues

Abstract

Enabling a 10 min fast charge for electric vehicles is a possible route to reduce range anxiety and increase the utility of electric vehicles. While lithium plating during fast charging is a known challenge, the full suite of limitations which occur in full cells during a 10 min fast charge are unknown. In the present work the central constraints of extreme fast charging are explored through extensive experiments and analysis in single layer graphite/NMC532 pouch cells. Methods of developing fast-charging protocols considering the impedance and transport limitations are presented and the relative benefits of altering the charging rate, profile, relaxation, etc., are investigated. Analysis during and at the end of cycling identified both known and unexpected aging pathways. The most distinct outcomes from the work are a significant increase in cell-to-cell variability as the number of fast charge cycles increase [up to 11% (1σ)] and the identification of distinct aging of the NMC532 positive electrode including cracking of the secondary particles and a trend toward under-lithiation of the positive electrode. While significant aging of the positive electrode was observed, only a few conditions had discernible Li plating and no distinct reversible Li signature was seen during periodic reference performance tests.

Extreme Fast‐Charging of Lithium‐Ion Cells: Effect on Anode and Electrolyte

“…Most of the capacity fade at the 8-C rate occurred before eight cycles; after that, there was only a slight additional fade. With cycling, the variability in the measured values of capacity tended to increase in a manner consistent with that reported by Tanim et al [55] By contrast, the variability in the 8-C cells decreased markedly and tended to remain constant after about eight cycles, i.e., after the bulk of the capacity loss.…”

Effect of Anode Porosity and Temperature on the Performance and Lithium Plating During Fast‐Charging of Lithium‐Ion Cells

“…Twenty‐four, single‐layer, xx3450 pouch cells (≈32 mAh) were made by the Cell Analysis, Modeling and Protoyping (CAMP) Facility at Argonne. [ 19 ] The electrodes in the cell measured 34 × 50 mm. The composition of the single‐sided electrode laminates is shown in Table 1 .…”

A Review of Existing and Emerging Methods for Lithium Detection and Characterization in Li‐Ion and Li‐Metal Batteries

“…[68] Optical Imaging/Microscopy: Owing to the ubiquitous nature of digital photography, optical imaging remains a very popular approach toward qualitatively recording the extent and heterogeneity of Li plating across the surface area of the anode. [6,72,[77][78][79] Imaging is referred to as pictures taken with a camera (such as cellphone camera), that does not have specialized focusing optics while microscopy explicitly uses focusing optics to furnish micrographs. Optical imaging is particularly effective in LIBs due to the distinct shiny nature of metallic Li contrasted against the dark graphite, which is a typically anode in LIBs, as well as the distinct colors of lithiated graphite species.…”

“…[85] Sagane et al observed the plating and stripping reactions of Li on a Cu substrate, while also noting the reactivity of the plated Li with any tiny amounts of oxygen and moisture in the SEM chamber, [22] as shown in Figure 6b. Tanim www.advancedsciencenews.com et al showed an increased C-rate resulting in a larger amount of plated Li, [6] while Honbo et al showed that defects on the graphitic anode surface suppressed the formation of Li dendrites. [86] Bieker et al used SEM to investigate the correlation between Li plating, SEI formation, and electrolyte decomposition at the Li metal anode surface.…”

“…Deuterium being heavier than hydrogen has much lower total neutron scattering cross section, thus making it easier to image Li in an electrolyte-containing cell. Additionally, the neutron contrast of Li can be tuned by enriching it with the 6 Li isotope , which interacts more strongly with [104] Copyright 2018, Springer Nature). b) 3D reconstructions of Li growth in a Li-Si and a Li-Li cell using phase-contrast X-ray tomography (Adapted with permission.…”