Fluid-enhanced surface diffusion controls intraparticle phase transformations

Title
Fluid-enhanced surface diffusion controls intraparticle phase transformations
Authors
홍지현이양 리헌그루 첸임기필임종우디미트리오스 프래게다키스피터 아티아이상철노만 진요제 모스콘지쉔 구안윌리엄 젠트유영상미란 가베르첵사이풀 이슬람마틴 바잔트윌리엄 츄Haitao D. Deng
Keywords
에너지소재; 에너지저장; 소재고도분석; 리튬이차전지
Issue Date
2018-10
Publisher
Nature materials
Citation
VOL 17-922
Abstract
Phase transformations driven by compositional change require mass flux across a phase boundary. In some anisotropic solids, however, the phase boundary moves along a non-conductive crystallographic direction. One such material is LiXFePO4, an electrode for lithium-ion batteries. With poor bulk ionic transport along the direction of phase separation, it is unclear how lithium migrates during phase transformations. Here, we show that lithium migrates along the solid/liquid interface without leaving the particle, whereby charge carriers do not cross the double layer. X-ray diffraction and microscopy experiments as well as ab initio molecular dynamics simulations show that organic solvent and water molecules promote this surface ion diffusion, effectively rendering LiXFePO4 a three-dimensional lithium-ion conductor. Phase-field simulations capture the effects of surface diffusion on phase transformation. Lowering surface diffusivity is crucial towards supressing phase separation. This work establishes fluid-enhanced surface diffusion as a key dial for tuning phase transformation in anisotropic solids.
URI
http://pubs.kist.re.kr/handle/201004/70168
ISSN
1476-1122
Appears in Collections:
KIST Publication > Article
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