The slow redox dynamics and dissolution of polysulfides in lithium-sulfur(Li-S)batteries result in poor rate performance and rapid decay of battery capacity,thus limiting their practical application.Ferroelectric bari...The slow redox dynamics and dissolution of polysulfides in lithium-sulfur(Li-S)batteries result in poor rate performance and rapid decay of battery capacity,thus limiting their practical application.Ferroelectric barium titanate(BT)nanoparticles have been reported to effectively improve the electrochemical performance of Li-S batteries due to the inherent self-polarization and high adsorption capacity of the BT nanoparticles towards polysulfides.Here in this paper,BT nanoparticles,behave as highly efficient electrocatalyst and demonstrate much higher redox dynamics towards the conversion reaction of polysulfides and Li2S than TiO2,as shown by both electrochemical measurements and density functional theory calculation.The coupling of the sulfur host of the hollow and graphitic carbon flakes(HGCF)and the BT nanoparticles(HGCF/S-BT)enable excellent electrochemical performance of Li-S batteries,delivering a0.047%capacity decay per cycle in 1000 cycles at 1 C,788 mAh g^-1 at 2 C and a reversible capacity of613 mAh g^-1 after 300 cycles at a current density of 0.5 C at a S loading of 3.4 mg cm^-2.HGCF/S-BT also shows great promise for practical application in flexible devices as demonstrated on the soft-packaged Li-S batteries.展开更多
Transition metal selenides have been widely studied as anode materials of sodium ion batteries(SIBs),however,the investigation of solid-electrolyte-interface(SEI)on these materials,which is critical to the electrochem...Transition metal selenides have been widely studied as anode materials of sodium ion batteries(SIBs),however,the investigation of solid-electrolyte-interface(SEI)on these materials,which is critical to the electrochemical performance of SIBs,remains at its infancy.Here in this paper,ZnSe@C nanoparticles were prepared from ZIF-8 and the SEI layers on these electrodes with and without reduced graphene oxide(rGO)layers were examined in details by X-ray photoelectron spectroscopies at varied charged/discharged states.It is observed that fast and complicated electrolyte decomposition reactions on ZnSe@C leads to quite thick SEI film and intercalation of solvated sodium ions through such thick SEI film results in slow ion diffusion kinetics and unstable electrode structure.However,the presence of rGO could efficiently suppress the decomposition of electrolyte,thus thin and stable SEI film was formed.ZnSe@C electrodes wrapped by rGO demonstrates enhanced interfacial charge transfer kinetics and high electrochemical performance,a capacity retention of 96.4%,after 1000 cycles at 5 A/g.This study might offer a simple avenue for the designing high performance anode materials through manipulation of SEI film.展开更多
基金supported by the Fundamental Research Funds for Central Universities(SCUT No.2019ZD22)Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06N569)。
文摘The slow redox dynamics and dissolution of polysulfides in lithium-sulfur(Li-S)batteries result in poor rate performance and rapid decay of battery capacity,thus limiting their practical application.Ferroelectric barium titanate(BT)nanoparticles have been reported to effectively improve the electrochemical performance of Li-S batteries due to the inherent self-polarization and high adsorption capacity of the BT nanoparticles towards polysulfides.Here in this paper,BT nanoparticles,behave as highly efficient electrocatalyst and demonstrate much higher redox dynamics towards the conversion reaction of polysulfides and Li2S than TiO2,as shown by both electrochemical measurements and density functional theory calculation.The coupling of the sulfur host of the hollow and graphitic carbon flakes(HGCF)and the BT nanoparticles(HGCF/S-BT)enable excellent electrochemical performance of Li-S batteries,delivering a0.047%capacity decay per cycle in 1000 cycles at 1 C,788 mAh g^-1 at 2 C and a reversible capacity of613 mAh g^-1 after 300 cycles at a current density of 0.5 C at a S loading of 3.4 mg cm^-2.HGCF/S-BT also shows great promise for practical application in flexible devices as demonstrated on the soft-packaged Li-S batteries.
基金supported by the Fundamental Research Funds for Central Universities(SCUT Grant No.2019ZD22)the Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06N569)。
文摘Transition metal selenides have been widely studied as anode materials of sodium ion batteries(SIBs),however,the investigation of solid-electrolyte-interface(SEI)on these materials,which is critical to the electrochemical performance of SIBs,remains at its infancy.Here in this paper,ZnSe@C nanoparticles were prepared from ZIF-8 and the SEI layers on these electrodes with and without reduced graphene oxide(rGO)layers were examined in details by X-ray photoelectron spectroscopies at varied charged/discharged states.It is observed that fast and complicated electrolyte decomposition reactions on ZnSe@C leads to quite thick SEI film and intercalation of solvated sodium ions through such thick SEI film results in slow ion diffusion kinetics and unstable electrode structure.However,the presence of rGO could efficiently suppress the decomposition of electrolyte,thus thin and stable SEI film was formed.ZnSe@C electrodes wrapped by rGO demonstrates enhanced interfacial charge transfer kinetics and high electrochemical performance,a capacity retention of 96.4%,after 1000 cycles at 5 A/g.This study might offer a simple avenue for the designing high performance anode materials through manipulation of SEI film.
