Polyoxometalates act as an electron sponge,processing multielectron redox reactions and acting as a fast ionic conductor.They show great potential as promising electrode materials for next-generation lithium ion batte...Polyoxometalates act as an electron sponge,processing multielectron redox reactions and acting as a fast ionic conductor.They show great potential as promising electrode materials for next-generation lithium ion batteries(LIBs).However,there are still some fundamental issues which should be solved before their application can be realized,such as determining the stable structural feature with reversible Li+ion insertion/desertion.In this work,polyoxovanadates(POVs)based materials of K_(4)Na_(2)V_(10)O_(28)·nH_(2)O(KNaV_(10))and Mg_(2)(NH_(4))2V_(10)O_(28)·nH_(2)O(MgV_(10))have been prepared and used as the electrode material for a Li+ion reservoir.The 10-core polyoxovanadate is demonstrated as a anionic building block and the 3D extended structure has been smartly tuned by counter cations.For MgV_(10),a 1D tunnel with an approximate size of 3Å×10Å was formed along the a axis by Mg^(2+)ions and[V_(10)O_(28)]^(6-)polyanions.The MgV_(10) shows a higher capacity,cycling stability,and rate performance than that of KNaV_(10) without tunnels.The capacity of MgV_(10) is about 160 mA h g^(-1) at a high discharge rate of 250 mA g^(-1),while it is only 118 mA h g^(-1) for KNaV_(10).Even after 60 discharge/charge cycles at 50 mA g^(-1),it displayed a capacity of 180 mA h g^(-1).The 1D tunnel in MgV_(10) facilitates the Li+ion transport and provides spatial Li storage sites,which promotes the electrochemical performance in LIBs.Moreover,the Mg^(2+)ions remained stable during battery cycling and promoted the 3D structure stability.This work demonstrates promising guidelines for the structural design of POVs based materials for Li storage.展开更多
基金financially supported by the National Natural Science Foundation of China(No.21603162 and 51671145)Tianjin Sci.&Tech.Program(17JCYBJC21500)+1 种基金major projects of new materials of Tianjin city(16ZXCLGX00120)the Fundamental Research Funds of Tianjin University of Technology.
文摘Polyoxometalates act as an electron sponge,processing multielectron redox reactions and acting as a fast ionic conductor.They show great potential as promising electrode materials for next-generation lithium ion batteries(LIBs).However,there are still some fundamental issues which should be solved before their application can be realized,such as determining the stable structural feature with reversible Li+ion insertion/desertion.In this work,polyoxovanadates(POVs)based materials of K_(4)Na_(2)V_(10)O_(28)·nH_(2)O(KNaV_(10))and Mg_(2)(NH_(4))2V_(10)O_(28)·nH_(2)O(MgV_(10))have been prepared and used as the electrode material for a Li+ion reservoir.The 10-core polyoxovanadate is demonstrated as a anionic building block and the 3D extended structure has been smartly tuned by counter cations.For MgV_(10),a 1D tunnel with an approximate size of 3Å×10Å was formed along the a axis by Mg^(2+)ions and[V_(10)O_(28)]^(6-)polyanions.The MgV_(10) shows a higher capacity,cycling stability,and rate performance than that of KNaV_(10) without tunnels.The capacity of MgV_(10) is about 160 mA h g^(-1) at a high discharge rate of 250 mA g^(-1),while it is only 118 mA h g^(-1) for KNaV_(10).Even after 60 discharge/charge cycles at 50 mA g^(-1),it displayed a capacity of 180 mA h g^(-1).The 1D tunnel in MgV_(10) facilitates the Li+ion transport and provides spatial Li storage sites,which promotes the electrochemical performance in LIBs.Moreover,the Mg^(2+)ions remained stable during battery cycling and promoted the 3D structure stability.This work demonstrates promising guidelines for the structural design of POVs based materials for Li storage.
