UNIST/Stanford team develops new Li-ion anode with silicon-nanolayer-embedded graphite/carbon; 1,043 Wh/l full LiCoO2 cell
Researchers affiliated with Ulsan National Institute of Science and Technology (UNIST), South Korea, and Stanford University have demonstrated the feasibility of a next-generation hybrid anode for high-capacity Li-on batteries using silicon-nanolayer-embedded graphite/carbon.
This architecture allows compatibility between silicon and natural graphite and addresses the issues of severe side reactions caused by structural failure of crumbled graphite dust and uncombined residue of silicon particles by conventional mechanical milling. A paper describing the work is published in the journal Nature Energy.
The new material shows a high first-cycle Coulombic efficiency (92%) and a rapid increase of the Coulombic efficiency to 99.5% after only 6 cycles with a capacity retention of 96% after 100 cycles, with an industrial electrode density of >1.6 g cm−3; areal capacity loading of >3.3 mAh cm−2; and <4 wt% binding materials in a slurry.
As a result, a full cell using LiCoO2 has demonstrated a higher energy density (1,043 Wh l−1) than with standard commercial graphite electrodes.
The researchers prepared the Si-nanolayer-embedded-graphite/carbon hybrids (SGC) using a chemical vapor deposition(CVD) process with a scalable furnace. This design has been demonstrated to produce 5 kg per batch using a small amount of silane gas (SiH4), and uniformly distributes Si nanolayers on graphite powder.
The material showed an enhanced reversible capacity (517 mAh g−1) with high CE (92%) at the first cycle. The hybrid overcomes the electrode expansion problem even in high electrode density cases.
The production equipment is capable of producing 300 kg of material in 6 hours per batch.
The work was supported by the IT R&D program of the Ministry of Trade, Industry & Energy (MOTIE) and Korea Evaluation Institute of Industrial Technology (KEIT), 2016 Research Fund of UNIST, and by the Office of Vehicle Technologies, Battery Materials Research Program of the US Department of Energy.
Minseong Ko, Sujong Chae, Jiyoung Ma, Namhyung Kim, Hyun-Wook Lee, Yi Cui, and Jaephil Cho (2016) “Scalable synthesis of silicon-nanolayer-embedded graphite for high-energy lithium-ion batteries.” Nature Energy 1 Article number: 16113 doi: 10.1038/nenergy.2016.113