Extremely thin layers of silicon may hold the key to unlocking up to six times more capacity in lithium-ion batteries.
Silicon can help the battery’s anode reach its maximum load of lithium, claim scientists from Helmholtz-Zentrum Berlin (HZB) Institute of Soft Matter and Functional Materials.
Researchers calculate the theoretical maximum capacity of silicon-lithium batteries lies at about 2300 mAh/g— as apposed to 372 mAh/g in lithium-ion batteries with graphite anodes.
The discovery came when the team used neutron reflectometry methods to track where the lithium ions adsorb in the silicon electrode, and also how fast they were moving at the Institut Laue-Langevin in Grenoble, France.
The team found lithium ions do not penetrate deeply into the silicon. During the charge cycle, a 20-nm anode layer develops containing an extremely high proportion of lithium.
Currently electrode materials such as graphite can only stably adsorb a limited number of lithium ions, which restricts the capacity of the batteries.
The team was headed by Prof. Matthias Ballauff. The finding were published in the journal ACSnano under the totle ‘Lithiation of Crystalline Silicon As Analyzed by Operando Neutron Reflectivity, ACS Nano’.
