  Identifying overpotential components of electrochemical systems enables
quantitative analysis of polarization contributions of kinetic processes under
practical operating conditions. However, the inherently coupled kinetic
processes lead to an enormous challenge in measuring individual overpotentials,
particularly in composite electrodes of lithium-ion batteries. Herein, the full
decomposition of electrode overpotential is realized by the collaboration of
single-layer structured particle electrode (SLPE) constructions and
time-resolved potential measurements, explicitly revealing the evolution of
kinetic processes. Perfect prediction of the discharging profiles is achieved
via potential measurements on SLPEs, even in extreme polarization conditions.
By decoupling overpotentials in different electrode/cell structures and
material systems, the dominant limiting processes of battery rate performance
are uncovered, based on which the optimization of electrochemical kinetics can
be conducted. Our study not only shades light on decoupling complex kinetics in
electrochemical systems, but also provides vitally significant guidance for the
rational design of high-performance batteries.
