whatever is the cause of the share price increase, I would say...

whatever is the cause of the share price increase, I would say that it is the same reason for the AVL share price increase.
Both RFX and AVL sell flow batteries, even though they are different chemistries.
AVL had its first big day on Jan 19, held for 3 days and then another big day today.
RFX had good days on Jan 20 & 21, held for 1 day, then another big day today.
The volumes for both RFX and AVL have both been huge.

Like RFX, AVL also had a speeding ticket a few days ago, and gave the same response as RFX.

IMO, someone with deep pockets has realized there is a future in Flow batteries and is hedging their bet between AVL and RFX.