As the battery market grows, developing a battery waste management economy becomes imperative. After primary use, the main options for discarded batteries are recycling, refurbishment, reuse, or disposal. Recycling involves extracting valuables materials from ground-up battery cells, while reuse and refurbishment involve direct use of packs or their components, with or without maintenance adjustments. Recycling and disposal are the most common battery waste pathways, while reuse and refurbishment practices require further understanding of battery degradation before being implemented on a large scale. Furthermore, relatively high recycling costs are motivation to pursue more cost-efficient recycling methods like direct recycling.

This work expands on previous studies on the statistical distribution of the state-of-health (SOH) of used LiFePO₄ (LFP) cells extracted from a hybrid-bus battery pack.¹ We characterize samples from used and pristine A123 M1-A and M1-B 26650 cells using XRD and SEM. We will compare the cell materials’ morphologies and structure to their electrochemical performance in two diagnostic tests: a constant-current cycling test and an electrochemical impedance spectroscopy test.

Preliminary data have been collected from used M1-A cells that demonstrated starkly different states-of-health during electrochemical testing—ranging in residual capacities from 2.2 Ah to 0.30 Ah. The low-SOH M1-A cell had severe anode delamination and morphological cracks in the center of the cylinder cross-section. Cathode delamination in the cell also increased towards the center of the cylinder. The high-SOH M1-A cell’s electrodes had a consistent morphology throughout the cell, but delamination was worst at the center of the cylinder’s cross-section.

In this presentation, we will summarize our x-ray diffraction and scanning electron microscopy data for the cells described in Table 1. We will also discuss technical pathways for direct recycling of active materials from LFP battery waste.

1. Ramirez-Meyers and J. Whitacre. “(Invited) Statistical Distribution and Feasibility for Re-Use of A123 LiFePO4 Cells from a Hybrid-Bus Battery Pack.” ECS Meeting Abstracts, no. 6, p. 1052. IOP Publishing, 2020.