Bifunctional sodium compensation of anodes for hybrid sodium-ion capacitors

The low initial Coulombic efficiency (ICE) for the electrodes which stems from electrolyte decomposition and irreversible sodium uptake by material itself, is one of reasons limiting large-scale sodium-ion capacitors (SICs). Here, we report a simple but precise bifunctional pre-sodiation Nb2O5 anode (as typical example) using naphthalene/2-methyltetrahydrofuran as pre-sodiated agent. agent realizes pre-activation to achieve stable cycling NaxNb2O5, thus compensating Na uptake. Moreover, this process offsets loss, facilitates formation robust inorganic-rich solid interphase layer. Stable high-energy SIC devices are achieved bulk loss anodes. This work provides new insights into tuning ICE sodium-storage next-generation scaled-up applications SICs.