Li2TiSiO5 receives much interest recently in lithium-ion battery anodes because of its attractive Liinsertion/extraction potential at 0.28 V(vs. Li+/Li), which bridges the potential gap between graphite and Li4 Ti5 O1...Li2TiSiO5 receives much interest recently in lithium-ion battery anodes because of its attractive Liinsertion/extraction potential at 0.28 V(vs. Li+/Li), which bridges the potential gap between graphite and Li4 Ti5 O12. However, Li2TiSiO5 suffers from the low intrinsic electronic conductivity and sluggish Liion transfer kinetics. In this work, we report lithium-ion insertion kinetics of Li2TiSiO5 by Na doping,achieving high-rate capability. Rietveld refinement of X-ray diffraction results reveals that Na doping can enlarge the space of Li slabs, thus reducing the Li-ion transfer barrier and enhancing the Li-ion diffusion kinetics. According to first-principles calculations, Na doping can tune the band structure of Li2TiSiO5 from indirect to direct band, leading to improved electronic conductivity and electrochemical performance. In particular, the Na-doped Li2TiSiO5(Li1.95 Na(0.05)TiSiO5) electrode exhibits outstanding rate capability with a high capacity of 101 m A h g^(-1) at 5 A g^(-1) and superior cyclability with a reversible capacity of 137 m A h g^(-1) under 0.5 A g^(-1) over 150 cycles.展开更多
Aqueous Zn-based energy-storage devices have aroused much interest in recent years.However,uncontrollable dendrite growth in the Zn anode significantly limits their cycle life.Moreover,the poor low-temperature perform...Aqueous Zn-based energy-storage devices have aroused much interest in recent years.However,uncontrollable dendrite growth in the Zn anode significantly limits their cycle life.Moreover,the poor low-temperature performance arising from the freezing of aqueous electrolytes at sub-zero temperatures restricts their practical applications in cold regions.Here,we fabricated low-temperature-tolerant and durable Zn-ion hybrid supercapacitors(ZHSCs)via modulating a co-solvent water/ethylene glycol electrolyte.The interaction of intermolecular hydrogen bonds between water and ethylene glycol as well as cation solvation was systematically investigated by tuning the co-solvent composition.The results illustrate that the ZnSO_(4)/water/ethylene glycol(65%)electrolyte possesses high ionic conductivity at low temperatures and effectively prevents the dendrite formation of the Zn anode.The as-fabricated ZHSCs exhibit long-term cyclability and are capable of working at sub-zero temperatures as low as -40℃.The present ZHSCs are anti-freezing and cost-effective,which may find new applications in the fields of next-generation electrochemical energy storage devices.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51772116 and 51972132)Program for HUST Academic Frontier Youth Team (2016QYTD04)。
文摘Li2TiSiO5 receives much interest recently in lithium-ion battery anodes because of its attractive Liinsertion/extraction potential at 0.28 V(vs. Li+/Li), which bridges the potential gap between graphite and Li4 Ti5 O12. However, Li2TiSiO5 suffers from the low intrinsic electronic conductivity and sluggish Liion transfer kinetics. In this work, we report lithium-ion insertion kinetics of Li2TiSiO5 by Na doping,achieving high-rate capability. Rietveld refinement of X-ray diffraction results reveals that Na doping can enlarge the space of Li slabs, thus reducing the Li-ion transfer barrier and enhancing the Li-ion diffusion kinetics. According to first-principles calculations, Na doping can tune the band structure of Li2TiSiO5 from indirect to direct band, leading to improved electronic conductivity and electrochemical performance. In particular, the Na-doped Li2TiSiO5(Li1.95 Na(0.05)TiSiO5) electrode exhibits outstanding rate capability with a high capacity of 101 m A h g^(-1) at 5 A g^(-1) and superior cyclability with a reversible capacity of 137 m A h g^(-1) under 0.5 A g^(-1) over 150 cycles.
基金supported by the National Natural Science Foundation of China(51772116 and 51972132)the program for HUST Academic Frontier Youth Team(2016QYTD04)。
文摘Aqueous Zn-based energy-storage devices have aroused much interest in recent years.However,uncontrollable dendrite growth in the Zn anode significantly limits their cycle life.Moreover,the poor low-temperature performance arising from the freezing of aqueous electrolytes at sub-zero temperatures restricts their practical applications in cold regions.Here,we fabricated low-temperature-tolerant and durable Zn-ion hybrid supercapacitors(ZHSCs)via modulating a co-solvent water/ethylene glycol electrolyte.The interaction of intermolecular hydrogen bonds between water and ethylene glycol as well as cation solvation was systematically investigated by tuning the co-solvent composition.The results illustrate that the ZnSO_(4)/water/ethylene glycol(65%)electrolyte possesses high ionic conductivity at low temperatures and effectively prevents the dendrite formation of the Zn anode.The as-fabricated ZHSCs exhibit long-term cyclability and are capable of working at sub-zero temperatures as low as -40℃.The present ZHSCs are anti-freezing and cost-effective,which may find new applications in the fields of next-generation electrochemical energy storage devices.
