Zeolite-Templated Carbon with Tailored Mesoporosity as a Kinetic Enhancer for Bio-Based Hard Carbon Sodium-Ion Battery Anodes

Hard carbons (HCs) are promising sodium-ion battery anodes but suffer capacity loss at high rates due to tortuous Na+ pathways. Here, a zeolite-templated carbon (ZTC) was introduced as a conductive, mesoporous additive (10 wt%) to a hazelnut-derived hard carbon (HEZ) to improve Na+ transport and rate performance. Structural and porosity analyses show complementary architectures: a microporous HEZ and a highly ordered ZTC with interconnected mesopores. Electrodes containing ZTC exhibit increased apparent ionic diffusion coefficients (from ~3.5 · 10−10 to ~16 · 10−10 cm2·s−1 Cathodic) and enhanced rate capability. Galvanostatic intermittent titration technique (GITT) analysis indicates accelerated Na+ transport in the low-voltage plateau region, and galvanostatic cycling demonstrates a sustained plateau capacity of ~100 mAh·g−1 for the ZTC-containing electrode after 50 cycles at 50 mA·g−1 (vs. ~30 mAh·g−1 for pristine HC). Although the ZTC increases the electrode surface area and lowers initial Coulombic efficiency, the addition markedly improves high-rate storage and capacity retention. These results demonstrate that a minor fraction of templated mesoporous carbon can effectively alleviate kinetic limitations in bio-derived HC anodes for sodium-ion batteries.