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ACS Appl Mater Interfaces. 2019 Apr 10;11(14):13257-13263. doi: 10.1021/acsami.9b01501. Epub 2019 Mar 27.

Minimized Volume Expansion in Hierarchical Porous Silicon upon Lithiation.

Author information

1
Environmental Molecular Sciences Laboratory , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States.
2
Department of Chemical Engineering , Kwangwoon University , Seoul 01897 , Republic of Korea.

Abstract

Silicon (Si) remains one of the most promising anode materials for next-generation lithium-ion batteries (LIBs). The key challenge for Si anodes is the huge volume change during lithiation-delithiation cycles that leads to electrode pulverization and rapid capacity fading. Here, we report a hierarchical porous Si (hp-Si) with a tailored porous structure [tunable primary pores (20-200 nm) and secondary nanopores (∼3-10 nm)] that can effectively minimize the volume expansion. An in situ transmission electron microscopy (TEM) study revealed that the hp-Si material with the same porosity but larger primary pores can more effectively accommodate lithiation-induced volume expansion, giving rise to a much reduced apparent volume expansion on both material and electrode levels. Chemomechanical modeling revealed that because of the different relative stiffnesses of the lithiated and unlithiated Si phases, the primary pore size plays a key role in accommodating the volume expansion of lithiated Si. The higher structural stability of the hp-Si materials with larger primary pores also maintains the fast diffusion channels of the connective pores, giving rise to better power capability and capacity retention upon electrochemical cycling. Our findings point toward an optimized hp-Si material with minimal volume change during electrochemical cycling for next-generation LIBs.

KEYWORDS:

lithium-ion battery; porous silicon; silicon anode; volume expansion

PMID:
30810309
DOI:
10.1021/acsami.9b01501

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