The role of carbon pore structure in tellurium/carbon cathodes for lithium-tellurium batteries

Tellurium (Te) is a rising electrode material for rechargeable batteries due to its prominent electrical conductivity (2 × 102 S m−1) and high volumetric capacity (2621 mAh cm−3). Currently, Li-Te batteries are mainly challenged by the large volume change accompanied by the redox conversion between Te and Li2Te. Herein, the abundant lignin is utilized to develop porous carbon as the Te host through carbonization and activation treatment. Our study reveals that both pore volume and surface area increase with the activation temperature and the different pore structure leads to the entirely different electrochemical performance of Te/C electrodes. It is found that an ideal porous carbon should possess a majority of micropores to confine Te and accommodate its volume change and a small portion of mesopores to facilitate electrolyte wetting and Li-ion transport. The optimized Te/C electrode delivers a reversible capacity of 418 mAh g−1, high capacity retention of 90% after 100 cycles, and exceptional cyclability over 1000 cycles at 2 C. This work suggests that lignin is a sustainable precursor for developing a unique carbon pore structure in battery applications.