Abstract
Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10-40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage.
| Original language | English |
|---|---|
| Article number | 3020 |
| Journal | Scientific Reports |
| Volume | 3 |
| DOIs | |
| State | Published - 2013 |
| Externally published | Yes |
Funding
We would like to thank Dr. Dave Geohegan and Dr. Alex Puretzky at ORNL for insightful discussions, and Mr. Robert Caprara for minor assistance with device testing. This work was supported by the National Science Foundation under CMMI grant # 1334269 and Vanderbilt start-up funds. J.W.M. was partially supported by ARO grant # W911NF-09-1-0101. TEM images were obtained from an instrument made possible by NSF grant EPS 1004083. SEM and CVD materials fabrication parts of this research were conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.