| 초록 |
Reversible insertion and extraction of a guest ion into the host crystal is the fundamental reaction underpinning insertion electrochemistry and has been widely applied to store energy and tune catalysts. It has been considered that the ion extraction and insertion reactions are reversible and following near-equilibrium paths for charge and discharge of lithium ion batteries, respectively. However, recent studies have revealed that the dynamics of the ion insertion and extraction can be altered by current density (reaction rate) and reaction direction in a phase-separating compound, Li1-xFePO4, using operando characterization techniques such as X-ray diffraction (XRD) and X-ray microscopy. We recently demonstrated that the kinetics of the reactions at solid-liquid interface governs the uniformity of ion insertion/extraction reactions by electro-autocatalyst and autoinhibitory. Here, we first show the asymmetric dynamics of ion insertion and extraction of a model solid-solution compound, layered lithium transition metal oxides. Combining operando XRD, electrochemistry, and population dynamics theory, we show that the non-constant reaction kinetics results in the heterogeneous delithiation and homogeneous lithiation, which eventually affects the fast-charging capability of lithium ion batteries. |
