The ion conductivity of a solid-state ion conductor generally increases exponentially upon reduction in ionmigration barrier.For prevalent cathode material LiCoO_(2),the room-temperature ion conductivity and migration...The ion conductivity of a solid-state ion conductor generally increases exponentially upon reduction in ionmigration barrier.For prevalent cathode material LiCoO_(2),the room-temperature ion conductivity and migrationbarrier are respectively around 10^(−4)S/cm and 0.3 eV.In this Letter,through first-principles calculations we predictthe existence of 1D superionicity as the Li ions in O_(2)LiCoO_(2)are transformed into Zn_(0.5)CoO_(2)or Li_(0.5)CoO_(2)via cation-exchange reaction or deintercalation.The ion migration barriers(0.01-0.02 eV)even lower than roomtemperature∼𝑘B𝑇are reduced by more than an order of magnitude compared with LiCoO_(2),which are facilitatedby facile transition of mobile ions between two coordination configurations.The room-temperature ion conductivityis estimated to be over 50 S/cm,enhanced by 2-3 orders of magnitude compared with the current highestreported value.Such unprecedented superionicity may also exist in other similar layered ion conductors,whichmay lead to technical advances and exotic effects such as ultrafast ion batteries and quantized ferroelectricity.展开更多
MXene is a new intercalation pseudocapacitive electrode material for supercapacitor application.Intensifying fast ion diffusion is significantly essential for MXene to achieve excellent electrochemical performance.The...MXene is a new intercalation pseudocapacitive electrode material for supercapacitor application.Intensifying fast ion diffusion is significantly essential for MXene to achieve excellent electrochemical performance.The expansion of interlayer void by traditional spontaneous species intercalation always leads to a slight increase in capacitance due to the existence of species sacrificing the smooth diffusion of electrolyte ions.Herein,an effective intercalation-deintercalation interlayer design strategy is proposed to help MXene achieve higher capacitance.Electrochemical cation intercalation leads to the expansion of interlayer space.After electrochemical cation extraction,intercalated cations are deintercalated mostly,leaving a small number of cations trapped in the interlayer silt and serving as pillars to maintain the interlayer space,offering an open,unobstructed interlayer space for better ion migration and storage.Also,a preferred surface with more-O terminations for redox reaction is created due to the reaction between cations and-OH terminations.As a result,the processed MXene delivers a much improved capacitance compared to that of the original Ti_(3)C_(2)T_(x)electrode(T stands for the surface termination groups,such as-OH,-F,and-O).This study demonstrates an improvement of electrochemical performance of MXene electrodes by controlling the interlayer structure and surface chemistry.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.22073034)。
文摘The ion conductivity of a solid-state ion conductor generally increases exponentially upon reduction in ionmigration barrier.For prevalent cathode material LiCoO_(2),the room-temperature ion conductivity and migrationbarrier are respectively around 10^(−4)S/cm and 0.3 eV.In this Letter,through first-principles calculations we predictthe existence of 1D superionicity as the Li ions in O_(2)LiCoO_(2)are transformed into Zn_(0.5)CoO_(2)or Li_(0.5)CoO_(2)via cation-exchange reaction or deintercalation.The ion migration barriers(0.01-0.02 eV)even lower than roomtemperature∼𝑘B𝑇are reduced by more than an order of magnitude compared with LiCoO_(2),which are facilitatedby facile transition of mobile ions between two coordination configurations.The room-temperature ion conductivityis estimated to be over 50 S/cm,enhanced by 2-3 orders of magnitude compared with the current highestreported value.Such unprecedented superionicity may also exist in other similar layered ion conductors,whichmay lead to technical advances and exotic effects such as ultrafast ion batteries and quantized ferroelectricity.
基金The work reported here was supported by the National Natural Science Foundation of China(Nos.52072196,52002199,52002200,52071171,and 52102106)Major Basic Research Program of Natural Science Foundation of Shandong Province(No.ZR2020ZD09)+4 种基金Natural Science Foundation of Shandong Province(Nos.ZR2019BEM042 and ZR2020QE063)the Innovation and Technology Program of Shandong Province(No.2020KJA004)the Open Project of Chemistry Department of Qingdao University of Science and Technology(No.QUSTHX201813)the Taishan Scholars Program of Shandong Province(No.ts201511034),China Postdoctoral Science Foundation(No.2020M683450),the Guangdong Basic and Applied Basic Research Foundation(Nos.2019A1515110933,2019A1515110554,2020A1515111086,and 2020A1515110219)the Innovation Pilot Project of Integration of Science,Education and Industry of Shandong Province(No.2020KJCCG04)。
文摘MXene is a new intercalation pseudocapacitive electrode material for supercapacitor application.Intensifying fast ion diffusion is significantly essential for MXene to achieve excellent electrochemical performance.The expansion of interlayer void by traditional spontaneous species intercalation always leads to a slight increase in capacitance due to the existence of species sacrificing the smooth diffusion of electrolyte ions.Herein,an effective intercalation-deintercalation interlayer design strategy is proposed to help MXene achieve higher capacitance.Electrochemical cation intercalation leads to the expansion of interlayer space.After electrochemical cation extraction,intercalated cations are deintercalated mostly,leaving a small number of cations trapped in the interlayer silt and serving as pillars to maintain the interlayer space,offering an open,unobstructed interlayer space for better ion migration and storage.Also,a preferred surface with more-O terminations for redox reaction is created due to the reaction between cations and-OH terminations.As a result,the processed MXene delivers a much improved capacitance compared to that of the original Ti_(3)C_(2)T_(x)electrode(T stands for the surface termination groups,such as-OH,-F,and-O).This study demonstrates an improvement of electrochemical performance of MXene electrodes by controlling the interlayer structure and surface chemistry.
