The unstable interfaces between a SnO_(2)anode and an electrolyte in a Li-ion battery dramatically impair the reversibility and cycling stability of lithiation and delithiation,resulting in low roundtrip Coulombic eff...The unstable interfaces between a SnO_(2)anode and an electrolyte in a Li-ion battery dramatically impair the reversibility and cycling stability of lithiation and delithiation,resulting in low roundtrip Coulombic efficiency(CE)and fast capacity decay of SnO_(2)-based anode materials.Herein,a simple strategy of modifying the solid electrolyte interphase(SEI)is developed to enhance the interfacial stability and lithium storage reversibility of SnO_(2)by compositing it with graphite(G)and an inorganic component of the SEI,such as Li_(2)CO_(3)or LiF,which results in the SnO_(2)-Li_(2)CO_(3)/G and SnO_(2)-LiF/G composite anodes with high CEs,large capacities and long cycle lives.Specifically,the SnO_(2)-Li_(2)CO_(3)/G composite anode exhibits an average initial CE of 79.6%,a stable reversible capacity of 927.5 mA hg^(-1)at a current rate of 0.2 A g^(-1),and a charge capacity over 1200 mA hg^(-1)with a CE>99%after 900 cycles at a higher current rate of 1 A g^(-1).It is revealed that Li_(2)CO_(3)induces the formation of a dense and stable SEI on SnO_(2)grains and inhibits the coarsening of nanosized Sn particles generated from the dealloying reaction in the SnO_(2)-Li_(2)CO_(3)/G electrode.Moreover,the CE and cycling stability of other alloying-type(Si)and conversion reaction(MnO_(2)and Fe_(3)O_(4))anodes can also be greatly promoted by simply milling with Li_(2)CO_(3).Thus,a universal and simple strategy is developed to achieve highly reversible and stable electrodes for large-capacity lithium storage.展开更多
The water-in-salt strategy successfully expands the electrochemical window of the aqueous electrolyte from1.23 to~3.0 V,which can lead to a breakthrough in the energy output of the aqueous battery system while maintai...The water-in-salt strategy successfully expands the electrochemical window of the aqueous electrolyte from1.23 to~3.0 V,which can lead to a breakthrough in the energy output of the aqueous battery system while maintaining the advantage of high safety.The expanded electrochemical window of the water-in-salt electrolytes can be ascribed to the decreased water activity and the solid electrolyte interphase formed on the anode.The solid electrolyte interphase in the aqueous system is not fully understood,and the basic composition,the structure,and the formation mechanism are still cloaked in mystery.This perspective summarizes the published research with emphasis on the most possible formation mechanism and composition of the interphase layer in the aqueous system.Further understanding of the interphase as well as rounded assessment of the water-in-salt electrolyte in practical operating conditions is encouraged.The full understanding of the interface will guide the design of aqueous electrolytes and help to build novel aqueous batteries with high safety and high energy density.展开更多
基金the National Natural Science Foundation of China(52071144,51621001,51822104 and 51831009)。
文摘The unstable interfaces between a SnO_(2)anode and an electrolyte in a Li-ion battery dramatically impair the reversibility and cycling stability of lithiation and delithiation,resulting in low roundtrip Coulombic efficiency(CE)and fast capacity decay of SnO_(2)-based anode materials.Herein,a simple strategy of modifying the solid electrolyte interphase(SEI)is developed to enhance the interfacial stability and lithium storage reversibility of SnO_(2)by compositing it with graphite(G)and an inorganic component of the SEI,such as Li_(2)CO_(3)or LiF,which results in the SnO_(2)-Li_(2)CO_(3)/G and SnO_(2)-LiF/G composite anodes with high CEs,large capacities and long cycle lives.Specifically,the SnO_(2)-Li_(2)CO_(3)/G composite anode exhibits an average initial CE of 79.6%,a stable reversible capacity of 927.5 mA hg^(-1)at a current rate of 0.2 A g^(-1),and a charge capacity over 1200 mA hg^(-1)with a CE>99%after 900 cycles at a higher current rate of 1 A g^(-1).It is revealed that Li_(2)CO_(3)induces the formation of a dense and stable SEI on SnO_(2)grains and inhibits the coarsening of nanosized Sn particles generated from the dealloying reaction in the SnO_(2)-Li_(2)CO_(3)/G electrode.Moreover,the CE and cycling stability of other alloying-type(Si)and conversion reaction(MnO_(2)and Fe_(3)O_(4))anodes can also be greatly promoted by simply milling with Li_(2)CO_(3).Thus,a universal and simple strategy is developed to achieve highly reversible and stable electrodes for large-capacity lithium storage.
基金supported by the National Natural Science Foundation of China(22075091 and 21773077)。
文摘The water-in-salt strategy successfully expands the electrochemical window of the aqueous electrolyte from1.23 to~3.0 V,which can lead to a breakthrough in the energy output of the aqueous battery system while maintaining the advantage of high safety.The expanded electrochemical window of the water-in-salt electrolytes can be ascribed to the decreased water activity and the solid electrolyte interphase formed on the anode.The solid electrolyte interphase in the aqueous system is not fully understood,and the basic composition,the structure,and the formation mechanism are still cloaked in mystery.This perspective summarizes the published research with emphasis on the most possible formation mechanism and composition of the interphase layer in the aqueous system.Further understanding of the interphase as well as rounded assessment of the water-in-salt electrolyte in practical operating conditions is encouraged.The full understanding of the interface will guide the design of aqueous electrolytes and help to build novel aqueous batteries with high safety and high energy density.
