(Invited) Enhanced Cycle Capacity of Lithium Ion Batteries with Nanocomposite Si Anodes Produced by Rapid Co-Condensation in Plasma Spray PVD

Tuesday, 30 May 2017: 12:00
Trafalgar (Hilton New Orleans Riverside)
K. Fukada, R. Ohta, and M. Kambara (Department of Materials Engineering, University of Tokyo)
Silicon (Si) is the promising candidate of anode for the next generation high-density lithium-ion batteries (LiB) owing to its 10 times greater theoretical capacities than the conventional carbonous material. This material however needs to be structured at nano-to-micron length scale to cope with inevitable volume change up to 400% during (de)lithiation reaction that leads eventually to fracture of the material and to a significant capacity drop in short cycles. Among various approaches for structuring proposed, battery industries are seeking for techniques with which high throughput production at reasonable cost is anticipated. In this respect, plasma spray physical vapor deposition (PS-PVD) can be a strong candidate. In fact, 20-40 nm nanoparticles (NP) are produced from metallurgical grade Si powders which is several dollars per kilogram and these particles used as anode of the battery have exhibited an improved capacity retention at longer battery cycles. Further improvement in cycle capacity has been observed with nanocomposite Si:Ni anode, in which NiSi2 are epitaxially attached on Si-NP through heterogeneous nucleation during co-condensation of Si-Ni vapors. Uniqueness of this anode is that crystalline Si (c-Si) anode remains even after 50th cycle while c-Si conventionally experiences the structural change to amorphous as a result of (de)lithiation. The electric resistance associated with anode is also found to reduce with Si:Ni-NP. These suggest that the epitaxial NiSi2 contributes mechanically and electrochemically to suppress the capacity decay during cycles. The detailed effect of additives will also be discussed in the presentation. This work was partly supported by Grant-in-Aid for Scientific Research (B) 15H04152 of Japan.

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