Unveiling Lithium Metal Anode Behavior through The Advancements and Applications of Titration Gas Chromatography

In the realm of energy storage technologies, lithium metal batteries have gained significant attention due to the global shift toward renewable energy systems. Accurate diagnosis and understanding of the attenuation mechanism of batteries are therefore essential for the development direction. Titration Gas Chromatography (TGC) is an effective tool for quantitively understanding the anode materials' cycling behavior. The dead Li in the cycled Lithium metal anode consists of trapped Li (Li⁰) and Solid electrolyte Interphase (SEI) Li⁺, in which only trapped Li can react with the protic solvent to generate the hydrogen (H₂), while SEI (Li⁺) does not. The ideal protic solvent, therefore, must meet specific criteria: 1) exclusively reacting with Li⁰ to generate H₂ gas; 2) displaying chemical inertness with SEI components or refraining from producing H₂ gas. Adhering to these conditions, quantifying H2 allows for the differentiation and quantification of trapped Li0 and SEI (Li⁺). With the optimal solvent selection, our investigations encompassed: 1) assessing corrosion effects on electrochemically deposited Li metal anode; 2) quantifying Li inventory in practical Li metal batteries3. We demonstrate the importance of using TGC techniques in quantitatively examining the Li inventory changes of the anode under various operating conditions. Beyond that, the results offer unique insights into identifying critical bottlenecks that enhance battery performance development.