An In-Depth Analysis of the Transformation of Tin Foil Anodes during Electrochemical Cycling in Lithium-Ion Batteries

Abstract

Tin foils have an impressive lithium-storage capacity more than triple that of graphite anodes, and their adoption could facilitate a drastic improvement in battery energy density. However, implementation of a dense foil electrode architecture represents a significant departure from the standard blade-cast geometry with a distinct electrochemical environment, and this has led to confusion with regards to the first cycle efficiency of the system. In this work, we investigate the unique behavior of a tin active material in a foil architecture to understand its performance as an anode. We find shallow cycling of the foil results in an irreversible formation (< 40 %) due to diffusional trapping, but intermediate and complete utilization allows for a remarkably reversible formation reaction (> 90 %). This striking nonlinearity stems from an in-situ transformation from bulk metal to porous electrode that occurs during formation cycles and defines electrode-level lithium-transport on subsequent cycles. An alternative cycling procedure for assessing the stability of foils is proposed to account for this chemomechanical effect.

Nanostructured Composite Foils Produced Via Accumulative Roll Bonding as Lithium-Ion Battery Anodes

“…Observation of the second electrochemical cycle shows this process resulted in a drastic transformation of the reaction kinetics, significantly improving lithium transport throughout the material (Figure c). This alteration in kinetics resulted in a recovery of previously trapped capacity, analogous to the recovery observed for pure tin foils . During subsequent cycling, the generated structure was able to accept lithium at 8 mA cm –2 without any risk of lithium plating (Figure d).…”

“…This alteration in kinetics resulted in a recovery of previously trapped capacity, analogous to the recovery observed for pure tin foils. 19 During subsequent cycling, the generated structure was able to accept lithium at 8 mA cm −2 without any risk of lithium plating (Figure 3d). It is expected that the system would be symmetrically capable of fast-discharge, but this was not tested to avoid the high areal-current electrodeposition of lithium associated with rate-testing of high-loading electrodes in the half-cell form factor.…”

“…In our recent work, we found that the formation of bulk tin foils may present with unexpected phenomena, including a highly utilization-dependent first cycle efficiency and a significant evolution of the electrode polarization. 13,19 To understand the realized electrochemical properties of these systems, tin, pewter, and the composite were assembled into coin cells and then lithiated and delithiated at 50 mA g −1 (Figure 2a). Significant differences were observed between the electrochemical alloying of each system.…”

“…This translates to a total theoretical capacity of approximately 797 mA h g –1 or 12 mA h cm –2 if all electrochemically active materials were fully utilized. In our recent work, we found that the formation of bulk tin foils may present with unexpected phenomena, including a highly utilization-dependent first cycle efficiency and a significant evolution of the electrode polarization. , To understand the realized electrochemical properties of these systems, tin, pewter, and the composite were assembled into coin cells and then lithiated and delithiated at 50 mA g –1 (Figure a).…”

Lithium aluminum alloy anodes in Li-ion rechargeable batteries: Past developments, recent progress, and future prospects

“…Heligman and Manthiram have tested 16 different metallic foils and concluded that In, Sn, and Al foils deliver promising capacities as well as formation efficiencies [36]. Some successful demonstrations of In foil [37,38], Sn foil [39][40][41][42][43], and Al foil anodes [43][44][45][46][47][48] can also support their conclusions. Novel alloy strategies using interdigitated eutectic alloys may further be a way to utilize one or more active metals, whilst maintaining some structural supporting matrix [39,49].…”