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Asymmetric Rate Behavior of Si Anodes for Lithium‐Ion Batteries: Ultrafast De‐Lithiation versus Sluggish Lithiation at High Current Densities
Author(s) -
Li Juchuan,
Dudney Nancy J.,
Xiao Xingcheng,
Cheng YangTse,
Liang Chengdu,
Verbrugge Mark W.
Publication year - 2015
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201401627
Subject(s) - anode , materials science , lithium (medication) , electrochemistry , diffusion , ion , current density , electrode , battery (electricity) , ohmic contact , analytical chemistry (journal) , thermodynamics , nanotechnology , chemistry , medicine , power (physics) , physics , organic chemistry , quantum mechanics , layer (electronics) , endocrinology , chromatography
The combined effect of lithium‐ion diffusion, potential‐concentration gradient, and stress plays a critical role in the rate capability and cycle life of Si‐based anodes of lithium‐ion batteries. In this work, Si nanofilm anodes are shown to exhibit an asymmetric rate performance: around 72% of the total available capacity can be delivered during de‐lithiation under a high current density of 420 A g ‐1 (100C where C is the charge‐rate) in 22 s; in striking contrast, only 1% capacity can be delivered during lithiation. A mathematical model of single‐ion diffusion is established to elucidate the asymmetric rate performance, which can be mainly attributed to the potential‐concentration profile associated with the active material and the ohmic voltage shift under high currents; the difference in chemical diffusion coefficients during lithiation and de‐lithiation also plays a role. This clarifies that the charge and discharge rates of lithium‐ion‐battery electrodes should be evaluated separately due to the asymmetric effect in the electrochemical system.