Eos Energy Storage Enters into Definitive Agreement to Combine with B. Riley Principal Merger Corp II; Combined Company to List on NASDAQ Under Symbol “EOSE”

• Transaction advances Eos’s mission to accelerate the growth of a low carbon, more resilient and sustainable energy future
• Proceeds to be used to drive commercialization of and expand manufacturing capacity to meet growing customer demand for Eos’s patented aqueous zinc-powered battery technology
• Pro forma implied enterprise value of the combined company is approximately $550 million

EDISON, N.J. September 8, 2020 -- Eos Energy Storage LLC (“Eos”), a leading manufacturer of safe, sustainable, low-cost, and long-duration zinc hybrid cathode (“Znyth™”) battery energy storage systems, and B. Riley Principal Merger Corp. II (NYSE: BMRG, BMRG WS, BMRG.U) (“BMRG”), a special purpose acquisition company sponsored by an affiliate of B. Riley Financial, Inc. (Nasdaq: RILY) (“B. Riley Financial”), today announced a definitive merger agreement for a business combination that would result in Eos becoming a publicly listed company. Upon closing of the transaction, the combined company will be renamed Eos Energy Enterprises, Inc. (“Eos Energy”) and intends to list its shares of common stock on Nasdaq under the ticker symbol “EOSE”.

Founded in 2008, Eos is focused on accelerating the growth of clean energy in the United States by deploying large scale stationary energy storage solutions that deliver reliable and cost-competitive power in a safe and environmentally sustainable way. Eos’s flagship product, the Eos Znyth® DC battery system, is designed to meet the requirements of the grid-scale energy storage market, is commercially available and scalable, and is manufactured in the United States. Znyth® technology requires just five core commodity materials that are derived from non-rare earth and non-conflict minerals, in addition to being fully recyclable. Eos’s battery is non-flammable and does not require any moving parts or pumps, which allows for simple upkeep and market-leading low-cost operations.