Kara D. Fong*, Clare P. Grey* and Angelos Michaelides*,
{"title":"纳米电解质中离子电导率降低的物理根源","authors":"Kara D. Fong*, Clare P. Grey* and Angelos Michaelides*, ","doi":"10.1021/acsnano.4c1895610.1021/acsnano.4c18956","DOIUrl":null,"url":null,"abstract":"<p >Ion transport through nanoscale pores is at the heart of numerous energy storage and separation technologies. Despite significant efforts to uncover the complex interplay of ion–ion, ion–water, and ion–pore interactions that give rise to these transport processes, the atomistic mechanisms of ion motion in confined electrolytes remain poorly understood. In this work, we use machine learning-based molecular dynamics simulations to characterize ion transport with first-principles-level accuracy in aqueous NaCl confined to graphene slit pores. We find that ionic conductivity decreases as the degree of confinement increases, a trend governed by changes in both ion self-diffusion and dynamic ion–ion correlations. We show that the self-diffusion coefficients of our confined ions are strongly influenced by the overall electrolyte density, which changes nonmonotonically with slit height based on the layering of water molecules within the pore. We further observe a shift in the ions’ diffusion mechanism toward more vehicular motion as the degree of confinement increases. Despite the ubiquity of ideal solution (Nernst–Einstein) assumptions in the field, we find that nonideal contributions to transport become more pronounced under confinement. This increase in nonideal ion correlations arises not simply from an increase in the fraction of associated ions, as is commonly assumed, but from an increase in ion pair lifetimes. By building a mechanistic understanding of confined electrolyte transport, this work provides insights that could guide the design of nanoporous materials optimized for efficient and selective ion transport.</p>","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"19 13","pages":"13191–13201 13191–13201"},"PeriodicalIF":16.0000,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsnano.4c18956","citationCount":"0","resultStr":"{\"title\":\"On the Physical Origins of Reduced Ionic Conductivity in Nanoconfined Electrolytes\",\"authors\":\"Kara D. Fong*, Clare P. Grey* and Angelos Michaelides*, \",\"doi\":\"10.1021/acsnano.4c1895610.1021/acsnano.4c18956\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >Ion transport through nanoscale pores is at the heart of numerous energy storage and separation technologies. Despite significant efforts to uncover the complex interplay of ion–ion, ion–water, and ion–pore interactions that give rise to these transport processes, the atomistic mechanisms of ion motion in confined electrolytes remain poorly understood. In this work, we use machine learning-based molecular dynamics simulations to characterize ion transport with first-principles-level accuracy in aqueous NaCl confined to graphene slit pores. We find that ionic conductivity decreases as the degree of confinement increases, a trend governed by changes in both ion self-diffusion and dynamic ion–ion correlations. We show that the self-diffusion coefficients of our confined ions are strongly influenced by the overall electrolyte density, which changes nonmonotonically with slit height based on the layering of water molecules within the pore. We further observe a shift in the ions’ diffusion mechanism toward more vehicular motion as the degree of confinement increases. Despite the ubiquity of ideal solution (Nernst–Einstein) assumptions in the field, we find that nonideal contributions to transport become more pronounced under confinement. This increase in nonideal ion correlations arises not simply from an increase in the fraction of associated ions, as is commonly assumed, but from an increase in ion pair lifetimes. By building a mechanistic understanding of confined electrolyte transport, this work provides insights that could guide the design of nanoporous materials optimized for efficient and selective ion transport.</p>\",\"PeriodicalId\":21,\"journal\":{\"name\":\"ACS Nano\",\"volume\":\"19 13\",\"pages\":\"13191–13201 13191–13201\"},\"PeriodicalIF\":16.0000,\"publicationDate\":\"2025-03-25\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://pubs.acs.org/doi/epdf/10.1021/acsnano.4c18956\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"ACS Nano\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://pubs.acs.org/doi/10.1021/acsnano.4c18956\",\"RegionNum\":1,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Nano","FirstCategoryId":"88","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acsnano.4c18956","RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
On the Physical Origins of Reduced Ionic Conductivity in Nanoconfined Electrolytes
Ion transport through nanoscale pores is at the heart of numerous energy storage and separation technologies. Despite significant efforts to uncover the complex interplay of ion–ion, ion–water, and ion–pore interactions that give rise to these transport processes, the atomistic mechanisms of ion motion in confined electrolytes remain poorly understood. In this work, we use machine learning-based molecular dynamics simulations to characterize ion transport with first-principles-level accuracy in aqueous NaCl confined to graphene slit pores. We find that ionic conductivity decreases as the degree of confinement increases, a trend governed by changes in both ion self-diffusion and dynamic ion–ion correlations. We show that the self-diffusion coefficients of our confined ions are strongly influenced by the overall electrolyte density, which changes nonmonotonically with slit height based on the layering of water molecules within the pore. We further observe a shift in the ions’ diffusion mechanism toward more vehicular motion as the degree of confinement increases. Despite the ubiquity of ideal solution (Nernst–Einstein) assumptions in the field, we find that nonideal contributions to transport become more pronounced under confinement. This increase in nonideal ion correlations arises not simply from an increase in the fraction of associated ions, as is commonly assumed, but from an increase in ion pair lifetimes. By building a mechanistic understanding of confined electrolyte transport, this work provides insights that could guide the design of nanoporous materials optimized for efficient and selective ion transport.
期刊介绍:
ACS Nano, published monthly, serves as an international forum for comprehensive articles on nanoscience and nanotechnology research at the intersections of chemistry, biology, materials science, physics, and engineering. The journal fosters communication among scientists in these communities, facilitating collaboration, new research opportunities, and advancements through discoveries. ACS Nano covers synthesis, assembly, characterization, theory, and simulation of nanostructures, nanobiotechnology, nanofabrication, methods and tools for nanoscience and nanotechnology, and self- and directed-assembly. Alongside original research articles, it offers thorough reviews, perspectives on cutting-edge research, and discussions envisioning the future of nanoscience and nanotechnology.