Micro-CaCO₃ conformal template synthesis of hierarchical porous carbon bricks: As a host for SnO₂ nanoparticles with superior lithium storage performance

We demonstrate a facile conformal template synthesis of hierarchical porous carbon bricks (HPCBs) via chemical vapor deposition (CVD) method using CH₄ as carbon source and micro-CaCO₃ bricks as a conformal template. The as-prepared HPCBs exhibit abundant interconnected meso/macro-sized cavities, large surface area, high graphitization degree and robust framework, which act as an efficient host to buffer the volume changes of Li-Sn alloying-dealloying when applied in lithium ion batteries. Ultrafine SnO₂ nanoparticles are easily loaded onto the inner surfaces of the HPCBs via a facile pyrolysis of tin (II) 2-ethylhexanoate at 300 °C in air. The SnO₂/HPCB electrode exhibits superior cycle stability and rate capability, delivering a high reversible capacity of 743.8 mA h/g after 180 cycles at 200 mA/g with capacity retention of 109.5%, which is much higher than that of HPCBs (308.6 mA h/g after 180 cycles at 200 mA/g with capacity retention of 87.7%). The hierarchical porous carbon materials synthesized using micro-CaCO₃ as a conformal template can be a promising general host for various electrochemical energy storage applications.