25-08-2017, 09:32 PM
Nanowire Lithium-Ion Batteries as Electrochemical Energy Storage for
Electric Vehicles
1Nanowire Lithium.pdf (Size: 75.38 KB / Downloads: 51)
Abstract
Nanowires offer advantages of a large surface to volume ratio, efficient electron
conducting pathways and facile strain relaxation. We will explore these advantages in a
nanowire battery architecture for high energy and high power battery for electrical
vehicles. In the past two months since funded by GCEP, we have made progress on
synthesis of nanowires and are testing their performance as battery electrodes.
Introduction
The rechargable battery is a promising technology for reversible electricity storage in
electric vehicles. Current electric vehicles are powered by lead-acid, NiCd or nickelmetal
hydride batteries, which are limited by their energy density and calendar lifetime.
The existing Li-ion battery technology, which uses LiCoO2 as cathode, lithiated graphite
(LiC6) as anode, and LiPF6-organic solvent as electrolyte, has been the most important
power source for portable electronics. However, the high cost and low production volume
due to the scarcity of Co are the major hurdles to their wide applications in light duty
vehicles. The solution is to decrease the cost and maximize the performance. The
electrolyte in general does not limit the Li-battery technology. We identify the following
as the most important areas to improve: 1) Use alternative cheaper and higher energy
density cathode materials to replace scarce Co oxides; 2) Replace the anode with higher
energy density and cheaper materials; 3) Maximize the performance by optimizing
battery device architecture. To realize electrochemical energy storage for electric
vehicles, we are working on a nanowire battery architecture combined with selection of
appropriate materials. We will explore the following advantages of using nanowires: 1)
Nanowires have a very large surface to volume ratio to contact with electrolyte. 2)
Nanowires form continuous conducting pathways for electrons through the electrodes. 3)
The nanowire geometry can promote facile strain relaxation during battery operation.
Background
Within the last two months since funded, there has not been much external
developments on nanowire battery electrodes. We are probably the first ones to work on
the nanowire battery concept.
Results
In the last two months since funded by GCEP, we have been making progress on the
synthesizing silicon nanowires (SiNWs. Figure 1 shows a scanning electron micrograph
(SEM) of SiNWs grown off a Si substrate. We have also been successful in growing
Progress
Transportation accounts for a quarter of global carbon dioxide emissions from energy
use, which is expected to approach one-third over the coming decades as the mobility of
the world’s population increases. The progress achieved will allows to test the nanowire
battery design concept towards high energy and high power Li battery for electrical
vehicles. Our proposed nanowire Li battery devices inter-convert electrical and chemical
energy with nearly 100% efficiency and can provide a carbon-free energy option for
electrical vehicles. This can allow significant reductions of greenhouse gas emissions in
the transportation sector, provided the electricity is produced with low net greenhouse gas
emissions. We believe that if our research is successful, the global greenhouse gas
emission can be substantially reduced over the long term.
Future Plans
We plan to carry out the following studies to realize our nanowire battery: 1) Test the
SiNWs for high energy anodes; 2) Develop the synthesis for high energy metal oxide
nanowires and test their performance as cathodes. 3) Understand the fundamental
structure, electronic transformation during charging and discharging.