If people are interested in this format of battery Pack ESS, then do a Google Search for ESS Telecom Battery. There are a large variety of companies producing these, some well known while others are unknown. BTW, Even EVE, CATL, GBS, LG, InSoFar, Growatt and many more...
DO NOTE: While they are "Rack Mountable" and can fit many types of Racks including surplus Server Racks they come in different sizes & weights so if you are considering rack-framing that is a consideration.