A new boundary condition forging the unprecedented self-consistence of galvanostatic intermittent titration technique

Abstract

Galvanostatic Intermittent Titration Technique (GITT) is widely applied to undertake the measurement of Li ion diffusion coefficient D in solid phase of electrode materials. However, various parameters adopted in GITT lead to considerable gaps of values of D in previous researches, making the measurement less rigorous. This work tries to introduce an indicator, the first derivative of ∆Eτ (or Eτ) vs t, to sift out the start of time region for the quasi-steady state. Further, by the introduction of a new boundary condition in GITT model, an enabler based on the slope ratio of ∂E/∂t at various titration currents is developed to reveal a more appropriate time region, realizing the high self-consistence of results calculated from GITT with different parameters. Particularly, the time region for Li+ diffusion in solid phase optimized from the enabler is even several orders of magnitude later than time constants derived from equivalent circuits. Based on the optimization of time region, the calculation of D via GITT achieves an unprecedented self-consistence within different titration currents over the un-optimized one. Such optimization may set a standard for calculate ion of Li+ diffusion in electrode materials.