Exhibit 99.1 News Release – February 22, 2024 Arcadium Lithium Releases Fourth Quarter and Full Year 2023 Results and Provides 2024 Full Year Outlook • Merger Between Allkem and Livent Completed on January 4, 2024 • Arcadium Lithium 2024 Outlook Highlighted by a 40% Increase in Lithium Carbonate and Hydroxide Volumes as a Combined Company • Projecting $60 to 80 million of Realized Synergies / Cost Savings in 2024 • Slowing Pace of Expansion in Light of Current Market Conditions and to Optimize Capital Effic ...