Journal
JOURNAL OF POWER SOURCES
Volume 522, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jpowsour.2022.231007
Keywords
Graphene; Silicon suboxides; Steric effect; Li-ion diffusion; Li-ion batteries
Funding
- National Natural Sci-ence Foundation of China [51872305, 52002381]
- Key R&D Program of Zhejiang Province [2018C01049]
- China Postdoctoral Science Foundation [2019M662125]
- Postdoctoral Science Foundation of Zhejiang Province
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Graphene as a functional additive in Li-ion batteries shows potential, but the stacking manner and mass loading need to be controlled within a certain range to prevent steric hindrance effects.
Due to high electrical conductivity and excellent mechanical properties, graphene has attracted extensive attention for Li-ion batteries, but generally as a functional additive with the content <= 1 wt%. Unfortunately, single graphene sheets and orderly stacked graphene films are likely to impede Li-ion transportation as a physical barrier. Herein, we compare pure graphene anodes with different stacking manners and SiO anodes wrapped with variant mass of graphene to unveil the steric hindrance. The rapidly fading capacity indicates a serious steric effect on lithium-ion diffusion once graphene mass loading goes beyond the critical value of similar to 0.3 mg cm(-2). When graphene stacked to parallel Li-ion diffusion direction, it delivers near-theoretical specific capacity, even for thick electrode up to 5.5 mg cm(-2). Furthermore, no remarkably adverse impact from graphene is shown in graphene wrapped SiO anodes even with 19 wt% graphene and at 4C in the half cells. Importantly, polarization associated voltage leap and average voltage demonstrate a significant steric effect when the graphene mass loading exceeds 0.33 mg cm(-2) in the commercial level pouch cells. In conclusion, the steric effect on electrochemical performances can be eliminated once the critical value of graphene mass loading in the electrode is below-0.3 mg cm(-2).
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