IEST In-Situ Gas Evolution Solutions Power Major ACS Nano Breakthrough: Quantify Reveals Initial Gas Evolution Behavior in Li-Rich Cathodes

Graphite lithiation—the process by which lithium ions intercalate into graphite anode layers during battery charging—proceeds through multiple ordered stage transitions that directly determine the rate and safety of fast charging. A 2026 JACS study by researchers at Nanjing University and CATL‘s 21C Innovation Lab has, utilizing an optical electrochemical imaging platform with high spatiotemporal resolution developed in collaboration with IEST Instrument, for the first time, directly visualized these phase transitions within single commercial natural graphite particles under real electrochemical conditions. The central finding is a previously unreported stochastic nucleation–confined propagation mechanism governing the early lithiation stages (1L→3L and 3L→2 transitions), contrasting sharply with the classic shrinking-core model observed in the final 2→1 stage. Critically, the rate-limiting step shifts between these stages: interfacial Li-ion transport dominates early transitions, while solid-state diffusion becomes the bottleneck in the final stage—a unified kinetic framework that resolves decades of academic debate and directly informs fast-charging anode design.