Currently, lithium-ion battery electrodes are made of graphite – we all know their performance. Silicon electrodes, on the other hand, could theoretically hold up to 10 times more lithium than graphite and around 30 percent more electricity for that matter.

The problem with silicon electrodes is that they swell when lithium enters them (the battery charges) and deflate when the battery discharges. After a few charge/discharge cycles, silicon electrodes are wasted. One solution would be Amprius’s solution that uses flexible and bendable silicon nanowires, but using a certain type of glue to hold the silicon particles together would be even better (read: cheaper).

This is the solution that Lawrence Berkeley National Laboratory (LBNL) researcher Gao Liu and his colleagues offered. He proposes a new type of glue that is both flexible and conductive and that, by using standard technologies already found in battery factories, can improve a lithium ion’s capacity by up to 30 percent.

“We have pushed these materials to the limit,” says Yury Gogotsi, professor of materials science and engineering at Drexel University. “Now what’s limiting us are the binders.”

Liu worked with theoretical chemists and came up with a list of the most conductive polymers, and then tried to make them stickier. What they got is a glue that can finally stick together the various pieces of silicon from a lithium ion battery, let them swell and then shrink without changing the battery’s electrical and physical characteristics.

The over 650 tests performed by Liu and his colleagues revealed the technology was very stable, and the battery made this way held 1,400 milliamps, compared to only 300 held by a similarly-sized graphite anode versions.

Although the typical capacity increase in lithium ion batteries is of about 5 percent per year, this discovery could go far beyond this figure, making batteries the energy storing solution of choice for car manufacturers and EV customers.

[via technologyreview]

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