Synergistic coupling of amorphous carbon and graphitic domains toward high-rate and long-life K+ storage

Abstract

Amorphous carbon materials hold great potential for practical use in potassium-ion batteries (PIBs) due to their abundant resources, low cost and high structural stability. However, given the challenge of sluggish potassiation kinetics, the rate performance of amorphous carbon is severely hindered. Herein, amorphous carbon compounded with graphitic domains (HG-CNTs) was proposed as an advanced anode for PIBs. As directly verified by in situ transmission electron microscopy (TEM), the graphitic domains guarantee fast K-ions transport in the carbon composite at a high current density, while the amorphous carbon shells ensure the structural integrity during potassiation, thus boosting its fast and durable K+ storage. As a PIB anode, the HG-CNTs electrode exhibits not only a super-stable long-term cyclability (191.6 mAh g−1 at 1 A g−1 with almost no capacity decay over 3000 cycles), but also an outstanding rate performance (184.5 mAh g−1 at 2 A g−1). Ex situ Raman and TEM results further suggest that the highly reversible structure of HG-CNTs is responsible for its superior electrochemical stability. This work provides helpful insights into the development of carbonaceous electrodes with both high rate capability and long cycle life for PIBs.