(Invited) Development and Application of Titration Gas Chromatography in Elucidating the Behavior of Anode in Lithium Batteries

Abstract

The accelerated transition to renewable energy systems worldwide has triggered increasing interest in energy storage technologies, especially in lithium batteries. Accurate diagnosis and understanding of the batteries degradation mechanism are essential. Titration Gas Chromatography (TGC) has been developed to quantitively understand the anode. The inactive Li in the cycled anode can be categorized into two kinds: 1) trapped Li0 (such as trapped lithiated graphite (LixC6), Li0, and lithium silicon alloy (LixSi)) and 2) solid electrolyte interphase (SEI) Li+. Noted that only trapped Li0 can react with the protic solvent to generate the hydrogen (H2), while SEI (Li+) does not1. Therefore, the H2 gas quantification can be correlated to the trapped Li0 as the foundation mechanism of TGC. With the optimal solvent selection, we successfully applied TGC to investigated: 1) the degradation behavior of Si-based anode materials2, 3; 2) corrosion effects on electrochemically deposited Li metal anode4; 3) the cycling behavior of Gr anode; 4) Li inventory quantification in practical Li metal battery5. We demonstrate the various application of TGC techniques in quantitatively examining the Li inventory changes of the anode. Beyond that, the results can provide unique insights into identifying the critical bottlenecks that facilitate battery performance development.