Distribution of relaxation times: Foundations, methods, diagnostics, and prognosis for electrochemical systems

The distribution of relaxation times (DRT) has become an indispensable technique for interpreting electrochemical impedance spectroscopy. This review traces the evolution of DRT from a powerful deconvolution tool for gaining mechanistic insight to a predictive engine for diagnostics and state estimation in fields such as batteries and fuel cells. The technique's intuitive appeal is challenged by its mathematically ill-posed nature, creating a "credibility gap" where subjective choices can yield misleading artifacts. Recent methodological advances in Bayesian and entropy-based frameworks provide greater robustness and uncertainty quantification. The path forward requires establishing a comprehensive analytical ecosystem built on community standards, benchmark datasets, and transparent reporting. This current opinion urges the community to embrace rigor and transform DRT from a specialized, expert-level tool into a reliable and reproducible cornerstone of electrochemical analysis.