Anodic Interfacial Evolution in Extremely Fast Charged Lithium-Ion Batteries

Abstract

Interfacial reaction mechanisms at the anode/separator interface play a central role in the performance and safety of lithium-ion batteries during fast charging. We report a mechanistic study on the evolution and interactions of the aging mechanisms at the anode/separator interface in lithium cobalt oxide/graphite pouch cells charged with variable charging rates (1–6C) over 10 cycles. In situ electrochemical measurements, including voltage relaxation, Coulombic efficiency, and direct current internal resistance, indicated an incremental lithium loss until the C rates were ≤5C. A substantial capacity fade is observed in the first few cycles of fast charging, but the magnitude of capacity fade progressively diminishes with the number of cycles, indicating a suppression in the lithium deposition mechanism. Post-mortem film thickness, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) analyses were performed to elucidate the evolution of electrolyte decomposition, the solid–electrolyte interface (SEI), lithium plating, and film fracture mechanisms with C rate. XPS measurements confirmed an increasing lithium concentration in an SEI film with an increase in the C rate. SEM images showed a growth of dendritic lithium on the anode surface from 1C to 3C. Precrack formation leading to an interfacial film fracture was observed at higher C rates. A differential analysis of the discharge capacity indicated a possible two-phase delithiation from the anode and reduced cathodic lithiation due to lithium loss at high C rates.

Building a rigid-soft coupling interphase by a reduction–oxidation collaborative approach with lithium difluorobis(oxalato) phosphate additives

“…Initially, the graphite half-cell was discharged at a high current in the LiDFBOP-added electrolyte to produce an initial SEI layer with numerous cracks. 38 Then, the cell was charged at a low current to allow the oxidation products of the electrolyte to completely fill the fractures in the initial SEI.…”

Super-resolved dynamics of isolated zinc formation during extremely fast electrochemical deposition/dissolution processes

“…At a lower charging rate, 30 the dendrites were formed at a lower rate and thus had more time to react with the electrolyte, leading to a thicker passivation layer during the plating process. 43 …”

“…Please do not adjust margins Please do not adjust margins At a lower charging rate, 30 the dendrites were formed at a slower rate and thus had more time to react with the electrolyte, leading to a thicker passivation layer during the plating process. 43 Spatiotemporal mapping was performed to study the formation of nanoscopic i-Zn (Figure 3c). The results indicated that the discharging rate plays an important role.…”

Fast‐Charging Strategies for Lithium‐Ion Batteries: Advances and Perspectives

“…[9] Li plating is associated with the processes including the Li + diffusion in the anodes and cathodes, Li + transport in the bulk electrolyte, Li + de-solvation before entering the solid electrolyte interphase (SEI), and the transport of bare Li + through SEI. [10] Therefore, Li + transport in the electrolyte and electrode/electrolyte interphase (EEI) is a crucial factor influencing the fastcharging performance of LIBs. The conventional electrolyte has poor redox stability, which continuously decomposes and causes the formation of thick EEI layers during fast-charging, leading to slow Li + transport kinetics through the EEI.…”

“…Li plating is associated with the processes including the Li + diffusion in the anodes and cathodes, Li + transport in the bulk electrolyte, Li + de‐solvation before entering the solid electrolyte interphase (SEI), and the transport of bare Li + through SEI [10] . Therefore, Li + transport in the electrolyte and electrode/electrolyte interphase (EEI) is a crucial factor influencing the fast‐charging performance of LIBs.…”