title: Ultrafast electrochemical lithiation of individual Si nanowire anodes.
abstract: Using advanced in situ transmission electron microscopy, we show that the addition of a carbon coating combined with heavy doping leads to record-high charging rates in silicon nanowires. The carbon coating and phosphorus doping each resulted in a 2 to 3 orders of magnitude increase in electrical conductivity of the nanowires that, in turn, resulted in a 1 order of magnitude increase in charging rate. In addition, electrochemical solid-state amorphization (ESA) and inverse ESA were directly observed and characterized during a two-step phase transformation process during lithiation: crystalline silicon (Si) transforming to amorphous lithium-silicon (Li(x)Si) which transforms to crystalline Li(15)Si(4) (capacity 3579 mAh·g(-1)). The ultrafast charging rate is attributed to the nanoscale diffusion length and the improved electron and ion transport. These results provide important insight in how to use Si as a high energy density and high power density anode in lithium ion batteries for electrical vehicle and other electronic power source applications.
authors.affiliation: Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
authors.forename: Xiao Hua
authors.initials: XH
authors.lastname: Liu
authors.forename: Li Qiang
authors.initials: LQ
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Zhong
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: He
authors.initials: H
authors.lastname: Zheng
authors.forename: Jiang Wei
authors.initials: JW
authors.lastname: Wang
authors.forename: Jeong-Hyun
authors.initials: JH
authors.lastname: Cho
authors.forename: Shadi A
authors.initials: SA
authors.lastname: Dayeh
authors.forename: S Tom
authors.initials: ST
authors.lastname: Picraux
authors.forename: John P
authors.initials: JP
authors.lastname: Sullivan
authors.forename: Scott X
authors.initials: SX
authors.lastname: Mao
authors.forename: Zhi Zhen
authors.initials: ZZ
authors.lastname: Ye
authors.forename: Jian Yu
authors.initials: JY
authors.lastname: Huang
mesh_terms: D004563:Electrochemistry; D004566:Electrodes; D008094:Lithium / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D053770:Nanowires / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D008094:Lithium; D012825:Silicon