Silicon based Nano-Scoops for High-Power Lithium-Ion Battery Anodes Si Al C 10% 94% 280% C Al Si Before Lithiation After Lithiation 10% 94% 280% C Al Si 10% 94% 280% 10% 94% 280% C Al Si Before Lithiation After Lithiation Rahul Mukherjee (Graduate Student) Department of Mechanical, Aerospace and Nuclear Engineering Rensselaer Polytechnic Institute 110 8 th Street, Troy, New York, USA.
16
Embed
Silicon based Nano-Scoops for High-Power Lithium-Ion ... · Rahul Mukherjee (Graduate Student) Department of Mechanical, Aerospace and Nuclear Engineering Rensselaer Polytechnic Institute
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Silicon based Nano-Scoops for High-Power Lithium-Ion Battery Anodes
Si
Al
C
10%
94%280%
C
AlSi
Before Lithiation
After Lithiation
10%
94%280%
C
AlSi
10%
94%280%
10%
94%280%
C
AlSi
Before Lithiation
After Lithiation
Rahul Mukherjee(Graduate Student)
Department of Mechanical,Aerospace and Nuclear Engineering
that can provide high power density and high energy density
• Research aim: To design electrode nano-architectures that can retain mechanical integrity over hunderds of cycles while providing a high capacity even when cycled at very high C-rates (> 20C)
Source: M. Winter, R. J. Brodd, Chem. Rev. 2004, 104, 4245.
Li-ion Cell Structure
Cathode: It is the source of Lithium.Ex: LiCoO2, LiFePO4
Anode: It is a host material for insertion of Li+.Ex: Graphite, porous carbon
Electrolyte: It offers a medium for the transport of Li+.Ex: solution of lithium-salt electrolytes, such as LiPF6, LiBF4, or LiClO4, in an organic solvent such as alkene carbonates
Source: R. Teki, M. K. Datta, R. Krishnan, T. C. Parker, T. –M. Lu, P. N. Kumta, N. Koratkar, Small, 2009, 5, 2236.
Is there room for improvement ?• Charge / discharge capacity: It is a measure of the total charge per unit
weight stored or recovered from the electrode material. The standard units for specific capacity are (mAh/g). The specific capacity is also a measure of the “Energy Density” of the battery.
• C-rate: A rate of nC corresponds to a full discharge in 1/n hours. This parameter monitors rate of charge/discharge as well as magnitude of current. It captures the “Power Density” of the battery.
Alternative Anode Materials: Quest for Higher Energy Density !
Alloy Capacity (mAh/g) Volumetric change (%)
Li22Si5 4200 400
Li3As 840 201
Li3Sb 564 147
LiAl 993 94
LiC6 372 10
Silicon has been proposed as the anode instead of carbon.Higher the Li capacity, larger the accompanying volumetric change
Source: A. Patil, V. Patil, D. Shin, J. Choi, D. Paik, S-J. Yoon, Mater. Res. Bull. 2008, 43, 1913.
Prior Art: Silicon Films as AnodeAdvantage: High theoretical charge capacity of 4200 mAh/g (10 times larger than carbon) Disadvantage: 400 % volume expansion leading to pulverization and delamination of the electrode films.
(a) Specific capacity plotted as a function of cycle number. (b) Stress-induced cracking of the film after a few cycles. (c) Delamination and peeling of the film from the collector electrode after extended cycling [2]
Source: J. P. Maranchi, A. F. Hepps, A. G. Evans, N. T. Nuhfer, P. N. Kumta, J. Electrochem. Soc. 2006, 153, A1246.
Nano-Silicon Reports
(a) Scanning electron micrographs of the porous Si particles indicating a pore wall size of ~40 nm. (b) Capacity vs. cycle number.
Source: H. Kim, B. Han, J. Choo, J. Cho, Angew. Chem. 2008, 47, 10151.
(a) Concept schematic of Si nanowire electrode (b) Scanning electron micrograph of Si nanowires that comprise the device anode. (c) Capacity vs. cycle number. Source: C. K. Chan, H. Peng, G. Lin, K. McIlwrath, X. F. Zhang, R. A. Huggins, Y. Cui, Nat. Nanotechnol. 2008, 3, 31.