I learned about this thanks to The Electric Viking and it is likely to mean higher energy density 2170 batteries in Tesla vehicles in the US. What Viking doesn’t cover is what the problem has been along the way.
Basically, using silicon instead of graphite in the anode of a Lithium Ion battery can substantially increase the energy density. Unfortunately, adding silicon increases expansion of the anode during cycling significantly shortening the cell life. The trick has been how to deal with the expansion or prevent it from happening.
Panasonic will be purchasing this new nano-silicon material from Sila, Sila was co-founded by ex-Tesla employee Gene Berdichevsky.