Scientists find way to increase capacity of lithium batteries

Scientists believe they can significantly increase the capacity of conventional lithium batteries by using silicon. Building anodes with this material enables a higher battery capacity.

The research was conducted by the Georgia Institute of Technology and reported in the authoritative scientific journal Nature Communications. In their research, the scientists describe a way to build batteries with an anode made of silicon instead of graphite. Such an anode can absorb considerably more lithium ions, in theory about ten times more, and that gives the battery considerably more capacity.

A battery based on silicon electrodes is not new, but no models have been built yet. This has to do with the vulnerability of the silicon when it is used in lithium batteries. For a long time, researchers did not know how to prevent the silicon from becoming brittle. A series of nanomechanical studies, both in the lab and computer simulations, by the researchers at Georgia Tech showed that there are indeed conditions in which silicon anodes in lithium batteries can work well.

Interestingly enough, silicon anodes become considerably more solid in certain higher concentrations of lithium ions. According to the researchers, this is because at higher concentrations the formed lithium-lithium and lithium-silicon compounds start to dominate. These are significantly more stable than bonds between silicon atoms that predominate at lower concentrations of lithium.

The research therefore shows which conditions are necessary to use silicon for lithium batteries. According to the scientists, it is possible to build batteries if the discharge takes into account the fact that the concentration of lithium around the anode must remain high enough. The scientists hope that their research will spark new interest in silicon as a building material for batteries.

Earlier, Samsung already came up with a battery concept that uses an anode that is partially provided with silicon. However, layers of graphene had to be placed over it. According to Georgia Tech, this is at the expense of battery capacity, making an anode that consists entirely of silicon preferred.

Two Georgia Tech researchers work on battery technology.