Hollow Multihole Carbon Bowls: A Stress–Release Structure Design for High-Stability and High-Volumetric-Capacity Potassium-Ion Batteries

Potassium-ion batteries are potential alternatives to lithium-ion batteries for large-scale energy storage considering the low cost and high abundance of potassium. However, it is challenging to obtain stable electrode materials capable of undergoing long-term potassiation/depotassiation due to the high accumulated stress associated with the huge volume variation of the electrode. Here, we simulate the von Mises stress distributions of four different carbon three-dimensional models under an isotropic initial stress by the finite element method and reveal the critical role of the structure of hollow multihole bowl on the strain-relaxation behavior. In this regard, nitrogen/oxygen co-doped carbon hollow multihole bowls (CHMBs) are synthesized via hydrothermal carbonization coupled with an emulsion-templating strategy using bio-mass as the carbon source. Consistent with our simulation results, the CHMBs anode remains stable for over 1000 cycles and delivers a high reversible capacity of 304 mAh g-1 at 0.1 A ...