Catalytic Defect‐Repairing Using Manganese Ions for Hard Carbon Anode with High‐Capacity and High‐Initial‐Coulombic‐Efficiency in Sodium‐Ion Batteries

Abstract

Hard carbon (HC) anodes have shown extraordinary promise for sodium‐ion batteries, but are limited to their poor initial coulombic efficiency (ICE) and low practical specific capacity due to the large amount of defects. These defects with oxygen containing groups cause irreversible sites for Na+ ions. Highly graphited carbon decreases defects, while potentially blocking diffusion paths of Na+ ions. Therefore, molecular‐level control of graphitization of hard carbon with open accessible channels for Na+ ions is key to achieve high‐performance hard carbon. Moreover, it is challenging to design a conventional method to obtain HCs with both high ICE and capacity. Herein, a universal strategy is developed as manganese ions‐assisted catalytic carbonization to precisely tune graphitization degree, eliminate defects, and maintain effective Na+ ions paths. The as‐prepared hard carbon has a high ICE of 92.05% and excellent cycling performance. Simultaneously, a sodium storage mechanism of “adsorption‐intercalation‐pore filling‐sodium cluster formation” is proposed, and a clear description given of the boundaries of the pore structure and the specific dynamic process of pore filling.

Thiophene-sulfur doping in nitrogen-rich porous carbon enabling high-ICE/rate anode materials for potassium-ion storage

“…As S1-NC is discharged from OCP to 1.0 V, the intensity of the D peak gradually decreases, which is attributed to the interaction between thiophene-type sulfur and K + . 55 In the discharge stage of 0.8 V–0.01 V, the G-band starts to shift to lower wavenumbers and its intensity gradually decreases, which stems from the electron occupation in the π* antibonding band and the weakening of the C–C bond during continuous intercalation of K + in the short-range ordered graphite domains. 54,56 Notably, the D and G-bands gradually return to their original states in the subsequent charge stage, demonstrating the good reversibility of the potassiation/depotassiation process.…”

Hard carbons: potential anode materials for potassium ion batteries and their current bottleneck

“…However, there is no large-scale regular graphite lamellar structure in the hard carbon, which is mainly composed of curly short-range ordered graphite domains. 60–62 The K + intercalation mechanism of hard carbons is different from that of traditional graphite due to the special micromorphology. In the potassiation process, the local intercalation reaction takes place between the turbine-like quasigraphitic domain layers of hard carbons.…”

Sustainable Fabrication of a Practical Hard Carbon Anode for a Sodium-Ion Battery with Unprecedented Long Cycle Life

“…26 The defectrepairing HC anode prepared by Zhao et al using manganese ion catalysis-assisted carbonation at 1400 °C has a high ICE of 92.1%. 27 Kamiyama et al successfully synthesized extremely high specific capacity HC for SIB at 1500 °C by the MgO template method due to the highly disordered structure and the large surface area. 28 So far, many people are still trying different methods to improve sodium-ion storage capability in HC, including enlarging the interlayer spacing so that the sodium ion can be rapidly embedded into graphite domains 29,30 and optimizing the pore structure to improve the storage of Na + /Na clusters in suitable pores.…”

“…Wang et al adopted chemical activation and high-temperature (1300 °C) carbonization to change the heat conversion path and form obturator holes in coal-derived HC to realize platform capacity storage of SIBs . The defect-repairing HC anode prepared by Zhao et al using manganese ion catalysis-assisted carbonation at 1400 °C has a high ICE of 92.1% . Kamiyama et al successfully synthesized extremely high specific capacity HC for SIB at 1500 °C by the MgO template method due to the highly disordered structure and the large surface area .…”