Pseudo-capacitive mechanisms can provide higher energy densities than electrical double-layer capacitors while being faster than bulk storage mechanisms.Usually,they suffer from low intrinsic electronic and ion conduc...Pseudo-capacitive mechanisms can provide higher energy densities than electrical double-layer capacitors while being faster than bulk storage mechanisms.Usually,they suffer from low intrinsic electronic and ion conductivities of the active materials.Here,taking advantage of the combination of TiS2 decoration,sulfur doping,and a nanometer-sized structure,as-spun TiO2/C nanofiber composites are developed that enable rapid transport of sodium ions and electrons,and exhibit enhanced pseudo-capacitively dominated capacities.At a scan rate of 0.5 mV s−1,a high pseudo-capacitive contribution(76%of the total storage)is obtained for the S-doped TiS2/TiO2/C electrode(termed as TiS2/S-TiO2/C).Such enhanced pseudocapacitive activity allows rapid chemical kinetics and significantly improves the high-rate sodium storage performance of TiO2.The TiS2/S-TiO2/C composite electrode delivers a high capacity of 114 mAh g−1 at a current density of 5000 mA g−1.The capacity maintains at high level(161 mAh g−1)even after 1500 cycles and is still characterized by 58 mAh g−1 at the extreme condition of 10,000 mA g−1 after 10,000 cycles.展开更多
Titanium oxide(TiO2),with excellent cycling stability and low volume expansion,is a promising anode material for lithium-ion battery(LIB),which suffers from low electrical conductivity and poor rate capability.Combini...Titanium oxide(TiO2),with excellent cycling stability and low volume expansion,is a promising anode material for lithium-ion battery(LIB),which suffers from low electrical conductivity and poor rate capability.Combining nano-sized TiO2 with conductive materials is proved an efficient method to improve its electrochemical properties.Here,rutile TiO2/carbon nanosheet was obtained by calcinating MAX(Ti3AlC2)and Na2C03 together and water-bathing with HC1.The lamellar carbon atoms in MAX are converted to 2D carbon nanosheets with urchin-like rutile TiO2 anchored on.The unique architecture can offer plentiful active sites,shorten the ion diffusion distance and improve the conductivity.The composite exhibits a high reversible capacity of 247 mA h g^-1,excellent rate performance(38 mA h g^-1 at 50 C)and stable cycling performance(0.014%decay per cycle during 2000 cycles)for lithium storage.展开更多
基金This work was financially supported by National Key R&D Program of China(No.2018YFB0905400)the National Natural Science Foundation of China(Nos.51925207,51872277,and U1910210)+2 种基金Dalian National Laboratory For Clean Energy(DNL)Cooperation Fund,the CAS(DNL180310)the Fundamental Research Funds for the Central Universities(Wk2060140026)Sofja Kovalevskaja award of the Humboldt Society.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No.823717-ESTEEM3.
文摘Pseudo-capacitive mechanisms can provide higher energy densities than electrical double-layer capacitors while being faster than bulk storage mechanisms.Usually,they suffer from low intrinsic electronic and ion conductivities of the active materials.Here,taking advantage of the combination of TiS2 decoration,sulfur doping,and a nanometer-sized structure,as-spun TiO2/C nanofiber composites are developed that enable rapid transport of sodium ions and electrons,and exhibit enhanced pseudo-capacitively dominated capacities.At a scan rate of 0.5 mV s−1,a high pseudo-capacitive contribution(76%of the total storage)is obtained for the S-doped TiS2/TiO2/C electrode(termed as TiS2/S-TiO2/C).Such enhanced pseudocapacitive activity allows rapid chemical kinetics and significantly improves the high-rate sodium storage performance of TiO2.The TiS2/S-TiO2/C composite electrode delivers a high capacity of 114 mAh g−1 at a current density of 5000 mA g−1.The capacity maintains at high level(161 mAh g−1)even after 1500 cycles and is still characterized by 58 mAh g−1 at the extreme condition of 10,000 mA g−1 after 10,000 cycles.
基金supported by the National Natural Science Foundation of China (NSFC, No. 51572011)the National Key Research and Development Program of China (No. 2017YFB0102004)the Fundamental Research Funds for the Central Universities (No. ZY1802)
文摘Titanium oxide(TiO2),with excellent cycling stability and low volume expansion,is a promising anode material for lithium-ion battery(LIB),which suffers from low electrical conductivity and poor rate capability.Combining nano-sized TiO2 with conductive materials is proved an efficient method to improve its electrochemical properties.Here,rutile TiO2/carbon nanosheet was obtained by calcinating MAX(Ti3AlC2)and Na2C03 together and water-bathing with HC1.The lamellar carbon atoms in MAX are converted to 2D carbon nanosheets with urchin-like rutile TiO2 anchored on.The unique architecture can offer plentiful active sites,shorten the ion diffusion distance and improve the conductivity.The composite exhibits a high reversible capacity of 247 mA h g^-1,excellent rate performance(38 mA h g^-1 at 50 C)and stable cycling performance(0.014%decay per cycle during 2000 cycles)for lithium storage.
