Simultaneous determination of reaction and diffusion kinetics in lithium-ion batteries using symmetric current pulse

Accurate electrochemical parameterisation of lithium-ion batteries is essential for physics-based modelling, electrode design, and safety assessment, yet conventional approaches such as galvanostatic intermittent titration (GITT) for diffusion and electrochemical impedance spectroscopy (EIS) for reaction kinetics are typically performed separately and require several weeks to generate comprehensive temperature and state of charge (SoC) resolved datasets. Here, a symmetric current pulse (SCP) methodology is introduced that determines both reaction and diffusion kinetics within a single integrated workflow. A symmetric charge-discharge pulse sequence at each SoC point preserves the open-circuit voltage and minimises SoC drift, enabling the thermodynamically consistent extraction of reaction kinetics (charge-transfer resistance, exchange current density, electrode reaction rate) and diffusion kinetics (lithium diffusion coefficient) directly from transient voltage responses. Subsequent EIS measurements at the same SoC provide independent validation of the reaction kinetics via distribution of relaxation times (DRT) analysis. Applied to NMC622//Li and graphite//Li half-cells over 20–100 % SoC and 10–45 °C, the methodology yields parameter maps in strong agreement with conventional GITT and EIS, while reducing total characterisation time from several weeks to approximately four days. The resulting temperature- and SoC-dependent kinetic maps reveal high-resistance and diffusion-limited operating regimes characterised by severe polarisation and transport limitations that may be associated with increased lithium-plating susceptibility. This provides a practical and fast route to safety-informed cell design and physics-based model parameterisation applicable across electrode chemistries and formats for energy storage.