Three-dimensional hierarchical porous hard carbon for excellent sodium/potassium storage and mechanism investigation

Hard carbons are one of the most promising anode materials for sodium/potassium-ion batteries (SIBs/ PIBs), which demonstrate favorable long charge/discharge plateaus, but suffer from low rate performance. Herein, we report a new design of NeP codoped hard carbon (NPHC) with three-dimensional (3D) hierarchical porous frameworks. Such unique structure provides bicontinuous ion/electron transportation paths, regulated electronic structure, enlarged interlayer spacing, and moderate surface area. The as prepared NPHC demonstrates a high reversible specific capacity (336 mAh g(-1) for SIBs, 339 mAh g(-1) for PIBs), along with a good rate performance of similar to 5.3 C. Particularly, an in-depth study on the charge storage mechanism for both SIBs and PIBs is conducted by combining in-situ Raman spectra and quasi insitu synchrotron X-ray diffraction analysis, whereby the coexistence of physical adsorption/graphitic layer intercalation, or intercalation/pore filling within certain potential ranges is detected, and the ion storage behavior at different charge/discharge stages is precisely identified. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The newly designed NeP codoped hard carbon (NPHC) shows high reversible specific capacity and good rate performance, with in-depth studies on the charge storage mechanism for sodium/potassium-ion batteries conducted using in-situ and quasi in-situ analysis methods.