biostudies-literatureLiu WNational Natural Science Foundation of China (National Science Foundation of China)9889https://www.ebi.ac.uk/biostudies/studies/S-EPMC11564968biostudies-literatureUnknown15(1)K-containing polyanion compounds hold great potential as anodes for sodium-ion batteries considering their large ion transport channels and stable open frameworks; however, sodium storage behavior has rarely been studied, and the mechanism remains unclear. Here, using a noninterference KTiOPO₄ thin-film model, the Na⁺ storage mechanism is comprehensively revealed by in situ/operando spectroscopy, aberration-corrected electron microscopy and density functional theory calculations. We find that incomplete K⁺/Na⁺ ion exchange occurs and eventually 0.15 K⁺ remains as a pillar to stabilize the tunnel structure. The pillar effect substantially maintains the volume change within 3.9%, much smaller than that of K⁺(Na⁺) inNature communicationsUnderstanding pillar chemistry in potassium-containing polyanion materials for long-lasting sodium-ion batteries.PMC1156496852172229, 52072136, 52272201, 52302303 and 51972257Li YLiu JXia JSang XHu WCui WShang JYi CWang ZLiu WfalseUnderstanding pillar chemistry in potassium-containing polyanion materials for long-lasting sodium-ion batteries.K-containing polyanion compounds hold great potential as anodes for sodium-ion batteries considering their large ion transport channels and stable open frameworks; however, sodium storage behavior has rarely been studied, and the mechanism remains unclear. Here, using a noninterference KTiOPO₄ thin-film model, the Na⁺ storage mechanism is comprehensively revealed by in situ/operando spectroscopy, aberration-corrected electron microscopy and density functional theory calculations. We find that incomplete K⁺/Na⁺ ion exchange occurs and eventually 0.15 K⁺ remains as a pillar to stabilize the tunnel structure. The pillar effect substantially maintains the volume change within 3.9%, much smaller than that of K⁺(Na⁺) in2024-01-01T00:00:00Z2024 Nov2026-07-16T21:48:21.632Z2025-04-07T04:30:14.175ZS-EPMC115649683954320610.1038/s41467-024-54317-8