Nanoporous Structure Formatioon in Dealloying of Li Alloys

Structural instability during cycling has long been a roadblock to the path of fulfilling Li alloys’ promise as high energy-density anodes for Li-ion batteries. While most investigations into this issue deal with mechanical fracturing, we focus our discussion on morphology evolution during the discharge process¹. Bi-continuous porous structures that are often associated with noble metal alloy dealloying also evolve during de-lithiation. An important issue in dealloying of Li that is inconsequential for noble metal dealloying is that of bulk diffusion of the electroactive component, which adds new complexity to this problem.  The interplay of bulk solid-state diffusion with percolation dissolution results in a variety of alternative morphologies including nonporous and core-shell particles. We use Li-Sn alloys as an exemplary system to illustrate how these factors impact the resulting dealloyed structures by investigating effects of alloy composition, dealloying rate and particle size. Our results have important implications for designing nanoporous materials from a variety of different parent-phase materials^2,3.

References:

1.      Chen, Q. & Sieradzki, K. Spontaneous evolution of bicontinuous nanostructures in dealloyed Li-based systems. Nat. Mater. 12, 1102–1106 (2013).

2.      Chen, Q. Bi-Continuous Nanoporous Structure Formation via Compound Decomposition. J. Electrochem. Soc. 161, H643–H646 (2014).

3.      Lin, F. et al. Phase evolution for conversion reaction electrodes in lithium-ion batteries. Nat. Commun. 5, 3358 (2014).