Exhibit 99.1 News Release – May 7, 2024 Arcadium Lithium Releases First Quarter 2024 Results • Solid First Quarter Results Driven by Average Realized Pricing for Lithium Hydroxide and Carbonate of Over $20,000 / product metric ton • On Track to Achieve$60 to 80 million of Realized Synergies / Cost Savings in 2024 • Multiple Expansions Provide Pathway to 170,000 LCEs1 of Capacity by 2026 PHILADELPHIA and PERTH, Australia, May 7, 2024 /PRNewswire/ -- Arcadium Lithium plc (NYSE: ALTM, ASX: LTM, “Arcadium Lith ...