Trash to treasure: recycling discarded agarose gel for practical Na/K-ion batteries

Abstract

Potassium and sodium ion batteries have emerged as promising next-generation energy storage devices owing to the merits of low cost and high availability. However, the large radius of Na/K ions hinders the development of suitable electrode materials. Herein, we propose a “trash to treasure” concept, transforming the wasted agarose from bio labs into high performance carbonaceous electrode materials for Na/K-ion batteries, which agrees well with the global carbon neutrality target. With the assistance of the dual heteroatom doping strategy, the as-synthesized carbons deliver unique properties including enlarged interspaces, abundant defective sites, and amorphous microstructures, which boost the capacitive behaviors and lead to a much better battery performance in both half cells and full cells. This work provides a facile and practical strategy to search and develop suitable electrode materials for Na/K-ion batteries, and deepens the understanding of structure–performance correlations over carbon electrodes.