Edge-enrich N-doped graphitic carbon: Boosting rate capability and cyclability for potassium ion battery

Nitrogen (N) doped graphitic-carbon materials as anode have been intensively studied for potassium-ion bat-teries (PIBs). However, insufficient N-doping content, especially the low edge-N ratio composed of pyridinic-N (N-6) and pyrrolic-N (N-5) cannot provide excellent rate capability and ultra-long cycle lifespan. Meanwhile, the intercorrelation between N-doping species and enlarged interlayer spacing remains unclear and needs to be further explored. Based on this, a series of N-doped graphitic carbons with different carbonization temperatures (denoted as ENGC-T) are controllably synthesized. It is found that a high edge-N doping ratio is conducive to increase active sites to promote capacitive-controlled K-storage. And the correlation between N-doping species and interlayer spacing reveals that N-5 configuration has a substantial effect on the interlayer spacing, due to its stronger electrostatic repulsion. Accordingly, the resultant ENGC-850 with both an ultra-high edge-N ratio (76.6%) and N-5 content (42%) achieves the most abundant defects and the largest interspacing, ensuring high capacity and cycling stability. Besides, good crystallization characteristics guarantees fast electron transfer, fa-voring conductivity. As expected, ENGC-850 electrode delivers high capacity, excellent rate (228.9 mAh g(-1) at 2 A g(-1)), and prolonged cycle lifespan (188.9 mAh g(-1) over 2200 cycles).

Automated summary

This study investigates nitrogen-doped graphitic carbon materials as anodes for potassium-ion batteries. The researchers found that a high edge-N doping ratio increases active sites and promotes capacitive-controlled K-storage. They also discovered that the N-5 configuration has a significant effect on interlayer spacing. The resulting ENGC-850 electrode exhibits high capacity, excellent rate capability, and prolonged cycle lifespan.