apanese Battery Trial Seeks to Transform How Grids Work: Energy, page-4

Fingers crossed the article linked on their website & emailed to subscribers means TNG are close to disclosing that Sumitomo are their VRFB partner.
A company of Sumitomo's calibre would change even the way I look at VRFBs due to Sumitomo's significant involvement in electricity generation & distribution throughout the world. At the level of say an ABB/Siemens or GE announcement.
IOW if Sumitomo decide that this technology would be a good fit somewhere, they have the engineering expertise, financial means, generation/transmission/retail & regulatory connections, to make it happen.