Tremella-like porous carbon derived from one-step electroreduction of molten carbonates with superior rate capability for sodium-ion batteries

As a promising alternative, sodium-ion batteries (SIBs) have been one of the hottest topics for emerging energy storage and conversion. Hard carbon (HC) material is kinetically favorable for sodium and electron transportation due to the amorphous structure with enlarged interlayer space. In this work, we report the electrochemical sodium storage behavior of tremella-like porous carbon synthesized via one-step electroreduction of molten Li-Na-K carbonates. As-prepared electrolytic carbon at 500 °C (C-500) and 6 V exhibits an interconnected micro-meso-macroporous structure with a high specific surface area of 691.77 m2 g−1. As an anode for SIBs, the C-500 sample exhibits high initial specific capacity of 402.1 mA h g−1 at 0.05 A g−1, superior rate performance (108 mA h g−1 after 1000 cycles at 5 A g−1) and wonderful cycling stability. The synergistic effect of unique porous structure and double surface capacitive storage characteristics lead to the exceptional performance. This work provides a facile pathway for the synthesis of novel carbon structure via molten salts electrolysis for SIBs application.