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 (LixSi) which transforms to crystalline Li15Si4 (capacity 3579 mAhg-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.
Original language | English (US) |
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Pages (from-to) | 2251-2258 |
Number of pages | 8 |
Journal | Nano letters |
Volume | 11 |
Issue number | 6 |
DOIs | |
State | Published - Jun 8 2011 |
Keywords
- Silicon nanowire
- carbon coating
- doping
- fast lithiation
- lithium ion battery