Chemical Engineering Journal, Vol.358, 1147-1154, 2019
N/S codoped carbon microboxes with expanded interlayer distance toward excellent potassium storage
Carbonaceous materials for potassium-ion batteries (PIBs) are quite attractive for the cost-effective feature. However, the cycle stability and rate performance of carbonaceous anode materials based on PIBs are limited, for the difficulty of accommodating large K ions (1.38 angstrom). Thus, the nitrogen (N) and sulfur (S) codoped carbon microboxes (NSC) with increased interlayer spacing is prepared via a carbonization-etching process. Unlike the traditional graphite, in which the K ions are difficult to insert into the restricted interlayer spacing, the NSC displays extremely large interlayer spacing of 0.412 nm, making the K ions more flexible during the insertion/extraction process in NSC. Moreover, ex-situ TEM study reveals that the layer structure of NSC is well-remained during the potassiation/depotassiation process. As a result, the NSC delivers super-long cycle life (180.5 mAh g(-1) at 500 mA g(-1) after 1000 cycles) and extraordinary rate ability (155.6 mAh g(-1) at 2 A g(-1)), which makes the NSC a promising anode material for PIBs.