By coating electrodes composed of silicon using a conductive polymer hydrogel, researchers have devised a method to increase the charge storage capacity for lithium-ion batteries dramatically.
Stanford University scientists have dramatically enhanced the efficiency of lithium-ion batteries by developing innovative electrodes made from conductor polymer hydrogel and silicon, which is a spongy material like the one used for soft lenses and other products used in everyday life.
In the edition of June 4 in Nature Communications, the magazine Nature Communications, the scientists discuss a brand new method of creating low-cost silicon-based batteries that could be used in many different electronic devices.
“Developing rechargeable lithium-ion batteries with high energy density and long cycle life is of critical importance to address the ever-increasing energy storage needs for portable electronics, electric vehicles, and other technologies,” said study co-author Zhenan Bao, a professo in chemical engineering at Stanford.
To discover a practical, affordable material that can increase the capacities of batteries made from lithium-ion, Bao, along with her Stanford colleagues, looked to silicon – an abundant green element with potential electronic characteristics.
“We’ve been trying to produce silicon-based electrodes for high-capacity lithium-ion batteries for several years,,” co-author of the study Yi Cui, associate professor of engineering and materials science at Stanford. “Silicon is ten times more powerful than the capacity to store charge than carbon, which is the standard material used for lithium-ion electrodes. The problem is that it expands and then breaks.”Studies have demonstrated that silicon particles can experience an increase of 400 percent in volume when paired with lithium.
If the battery gets discharged or charged and the particles are bloated, they tend to split and lose contact with electrical. To circumvent these technical limitations, the Stanford team employed a method called in situ synthesis polymerization, a coating of silicon nanoparticles in the hydrogel that was conducted.
A new way
This technique enabled the researchers to develop a lithium-ion battery that maintained the capacity to store energy for 5 000 cycles of charge and discharge. “We attribute the exceptional electrochemical stability of the battery to the initial nanoscale architecture of the silicon-composite electrode,
” Bao explained.
Utilizing an electron microscope that scans, researchers discovered that this porous matrix was filled with spaces that allow silicon nanoparticles in the matrix to expand when lithium is introduced. The matrix also creates an intricate three-dimensional structure that forms an electronic conducting pathway when charging and charging and.
“It turns out that hydrogel has binding sites that latch onto silicon particles well and at the same time frame provide channels for the fast transport of electrons and lithium ions,” explained Cui, the principal investigator at the Stanford Institute for Materials and Energy Sciences and as well the SLAC National Accelerator Laboratory.
“That is a highly effective combination.”A simple mix of silicon and hydrogel was ineffective as the in-situ synthetic polymerization technique. “Making the hydrogel first and then mixing it with the silicon particles did not work well,” Bao stated. “It necessitated an additional process that diminished the battery’s efficiency. Our method ensures that every silicon nanoparticle gets encapsulated in a conductive polymer layer and joined to the hydrogel framework. This improves batteries’ overall durability.”
Resolving the issue of fire
The majority of hydrogel is water. It can trigger lithium-ion batteries to burn and cause a fire – a possible issue that the team of researchers was required to resolve. “We utilized the three-dimensional network property of the hydrogel in the electrode, however in the ultimate production phase, the water was removed,
” Bao explained.
“You don’t want water in a very lithium-ion battery.”
While a few technical problems are still to be resolved, Cui is optimistic about possible commercial applications for the latest method to make electrodes made from the silicon as well as different materials.”The electrode fabrication technique that is used study can be used in conjunction with current manufacturing techniques for batteries,” he said. “Silicon, as well as hydrogels, are affordable and readily accessible. These elements could enable the use of high-performance silicon-composite electrodes that can be developed for new lithium-ion battery technology. It’s a simple process that has produced an effective outcome.”
The former Stanford postdoctoral fellows Hui Wu, now a faculty member at the Tsinghua University of Beijing, and Guihua Yu, who is now an instructor at the University of Texas Austin and co-lead authors on the study. The other authors include Stanford guest scholar Lijia P. and graduate students Nan Liu and Matthew McDowell.
The research was funded through The Precourt Institute for Energy ofStanford and The U.S. Department of Energy through the SLAC Laboratory Directed Research and Development Program. Additionalsupport was from the Natural Science Foundation of China and The U.S. National Science Foundation, and the Stanford Graduate Fellowships in Science and Engineering.