B, N stabilization effect on multicavity carbon microspheres for boosting durable and fast potassium-ion storage.

Heteroatom-rich carbon materials deliver superior potassium storage capacity owing to the abundant active sites, but their stability and conductivity are damaged because of the numerous defects and distortion of π-conjugated system. In this work, we amended the adverse influences of heteroatoms on carbon materials through the B, N stabilization effect. Due to an amending effect of B atoms on the N-doped carbon matrix, the integrity of the carbon skeleton and stability of the system are significantly enhanced, and the undesirable defects are transformed into favorable active sites, resulting in the simultaneous improvement of K storage capacity, rate performance and cyclic stability. The stabilized materials have a highly reversible carbon structure and fast K transfer kinetics, leading to high reversible capacity (300 mA h g at 0.1 A g), good rate performance (107.2 mA h g at 10 A g) and superior cyclic stability (75.3 % capacity retention from cycle 11 to 2000 at 1 A g). Consequently, the constructed devices perform excellent energy densities of 158.8 and 40.7 Wh kg under power densities of 100 and 11250 W kg, respectively. This work proposes an effective strategy for significantly improving heteroatom-rich carbon materials, which broadens its application fields in high-performance potassium ion storage.