Extreme Fast Charging: Effect of Positive Electrode Material on Crosstalk

Abstract

Extreme fast charging (XFC) is a key requirement for the adoption of battery-based electric vehicles by the transportation sector. However, XFC has been shown to accelerate degradation, causing the capacity, life, and safety of batteries to deteriorate. We tested cells containing five positive electrode chemistries, LFP (olivine structure), LMO (spinel), LCO (layered), NMC811 (layered), and NCA (layered), using fast-charging protocols. After testing, the negative electrodes from cells containing positive electrodes crystallizing with a layered structure were found to have more lithium deposited on their surfaces. Those crystallizing with a layered structure also tended to have a larger increase in impedance than those crystallizing with a spinel or olivine structure. Characterization of the negative electrodes by X-ray photoelectron spectroscopy showed that using the concentrations of LiF and LixPOyFz as metrics, the concentration of LiF in the positive electrodes is LFP > LMO > LCO ~ NMC811 > NCA; and for LixPOyFz, the order is LMO > LFP > NCA > NMC811 > LCO. Clearly, the positive-electrode material was influencing the amounts of these materials formed.

Quantitative Analysis of Origin of Lithium Inventory Loss and Interface Evolution over Extended Fast Charge Aging in Li Ion Batteries

“…Transition metal dissolution from the positive electrode (e.g., Mn 2+ ) and deposition on the graphite anode are other potential causes of LLI with cell aging. , Large correlation coefficients between Mn concentration quantified by ICP-OES and LLI were found for both 1 C (>0.99) and 9 C (>0.98), while a smaller value (∼0.79) was found for 6 C.…”

“…Thus, a variety of strategies to mitigate Li plating have been proposed, such as utilizing composite materials, altering the structure of graphite, , optimizing charging protocols, and developing advanced electrolytes . In parallel, the cathode also exhibits significant performance decay under XFC conditions due to surface/interphase issues, , increased cell impedance, loss of active material (LAM), − and mechanical degradation. , …”

Exploring the Promise of Multifunctional “Zintl-Phase-Forming” Electrolytes for Si-Based Full Cells

“…The Parr bombs were inserted into the stainless-steel sleeves and heated at 140 °C in a furnace for 48 h. Samples were diluted to 15 mL in a centrifuge tube with distilled, deionized water. The concentrations of Si, Mg, Ca, Li, and Cu were measured using a PerkinElmer NexION 2000 inductively coupled mass spectrometer, which was calibrated with standards prepared from NIST traceable solutions (Ultra Scientific, North Kingstown, RI) …”

“…SEM/ EDS data were obtained using a JEOL JSM-6610LV/coupled with an EDS detector (Oxford). As described in an earlier work, 25 electrode samples were transferred into a SEM chamber without air exposure using an airtight holder. Scanning transmission electron microscopy (STEM)/EDS characterizations were performed at 200 kV on an FEI Talos F200X TEM/STEM in the Center for Nanoscale Materials at Argonne National Laboratory.…”

“…The concentrations of Si, Mg, Ca, Li, and Cu were measured using a PerkinElmer NexION 2000 inductively coupled mass spectrometer, which was calibrated with standards prepared from NIST traceable solutions (Ultra Scientific, North Kingstown, RI). 25…”