Phytic acid-induced nitrogen configuration adjustment of active nitrogen-rich carbon nanosheets for high-performance potassium-ion storage

Abstract

As a conventional modification approach, nitrogen doping in carbon can greatly improve the electrochemical performance for potassium (K)-ion storage. However, we realized that the improvement of electrochemical performance by simple nitrogen doping alone in carbon was not as good as we expected. In this work, we develop a new approach to design active nitrogen-rich carbon nanosheets (PANC) by phytic acid induction, which present a remarkable improvement specific capacity of 317 mA h g⁻¹ after 100 cycles at 50 mA g⁻¹ and 202 mA h g⁻¹ at 500 mA g⁻¹, even after 3200 cycles. Density functional theory (DFT) calculations confirm the increased pyridinic-N as active sites contributes towards the enhancement of K-ion adsorption ability. In addition, our calculations illustrate that pyridinic-N exhibits a lower energy barrier of 0.16 eV compared to that of 1.12 eV for pyrrolic-N, indicating that pyridinic-N in carbon is the critical factor to improving the K-ion storage performance for our PANCs. This result was also confirmed by electrochemical impedance spectroscopy and pseudocapacitance analysis. We believe that our work describes the development of an effective approach to realize active N adjustment, which will inspire the design of high-performance anode materials for K-ion storage.