Lithium-sulfur batteries(LSBs)are promising as the next generation energy storage options.However,their wide applications have been technically challenged by the diffusion losses of polysulfides and polysulfide shuttl...Lithium-sulfur batteries(LSBs)are promising as the next generation energy storage options.However,their wide applications have been technically challenged by the diffusion losses of polysulfides and polysulfide shuttle effect.In this work,the small organic molecules of 2,5-dichloropyrazine(2,5-DCP)were combined with Co-doped carbon(CoA NAC)flakes to achieve the synergic effect of the covalent and chemical sulfur fixation,so as that the immobilization-conversion of polysulfides in LSBs was greatly enhanced.More specifically,the nucleophilic substitution of the 2,5-DCP additive in the electrolyte with polysulfides formed the CAS bonds.Through the further covalent N-Li bonds between the N atoms in 2,5-DCP and polysulfides,sulfur fixation was achieved in the form of solid organosulfur.Meanwhile,the CoA NAC flakes served as the sulfur cathode to chemically anchor the polysulfides.The interaction mechanism between CoA NAC/2,5-DCP and polysulfides was explored by the density functional theory(DFT)calculations and in-situ infrared spectroscopy.The results showed that the optimal“with 2,5-DCP”sample-assembled LSB exhibited an initial discharge specific capacity of 1244 mA h g^(-1)at 0.2C,and a capacity decay rate of 0.053%per cycle was displayed after 800 cycles at 1C.The good cycling stability with a high sulfur-loaded electrode sample suggested that the synergic effect of covalent/chemical sulfur fixation enabled the enhancement of polysulfides immobilization-conversion in LSBs.展开更多
The crystallization behavior of desulfurization product is directly related to its high-temperature-resistant ability.Effects of the additive on the sulfur-fixation efficiency of the Ba-sulfur-fixation agent and also ...The crystallization behavior of desulfurization product is directly related to its high-temperature-resistant ability.Effects of the additive on the sulfur-fixation efficiency of the Ba-sulfur-fixation agent and also on the crystallization behavior of the sulfur-fixation product were studied when CaCO 3 and BaCO 3 were used as the desulfurization agent and MgO and SrCO 3 used as the assistant sulfur-fixation agent. The result shows that increase of sulfur-fixation capability for the additive is not owe to their directly react to form sulfate or interact with CaCO 3 and BaCO 3 to form composite mineral heat-resistant in high temperature, but owe to their activation to sulfur-fixation reaction of the sulfur-fixation agent.展开更多
基金the financially supports from the National Natural Science Foundation of China(51963004)the Natural Science Foundation of Shandong Province of China(ZR2020MB024)。
文摘Lithium-sulfur batteries(LSBs)are promising as the next generation energy storage options.However,their wide applications have been technically challenged by the diffusion losses of polysulfides and polysulfide shuttle effect.In this work,the small organic molecules of 2,5-dichloropyrazine(2,5-DCP)were combined with Co-doped carbon(CoA NAC)flakes to achieve the synergic effect of the covalent and chemical sulfur fixation,so as that the immobilization-conversion of polysulfides in LSBs was greatly enhanced.More specifically,the nucleophilic substitution of the 2,5-DCP additive in the electrolyte with polysulfides formed the CAS bonds.Through the further covalent N-Li bonds between the N atoms in 2,5-DCP and polysulfides,sulfur fixation was achieved in the form of solid organosulfur.Meanwhile,the CoA NAC flakes served as the sulfur cathode to chemically anchor the polysulfides.The interaction mechanism between CoA NAC/2,5-DCP and polysulfides was explored by the density functional theory(DFT)calculations and in-situ infrared spectroscopy.The results showed that the optimal“with 2,5-DCP”sample-assembled LSB exhibited an initial discharge specific capacity of 1244 mA h g^(-1)at 0.2C,and a capacity decay rate of 0.053%per cycle was displayed after 800 cycles at 1C.The good cycling stability with a high sulfur-loaded electrode sample suggested that the synergic effect of covalent/chemical sulfur fixation enabled the enhancement of polysulfides immobilization-conversion in LSBs.
文摘The crystallization behavior of desulfurization product is directly related to its high-temperature-resistant ability.Effects of the additive on the sulfur-fixation efficiency of the Ba-sulfur-fixation agent and also on the crystallization behavior of the sulfur-fixation product were studied when CaCO 3 and BaCO 3 were used as the desulfurization agent and MgO and SrCO 3 used as the assistant sulfur-fixation agent. The result shows that increase of sulfur-fixation capability for the additive is not owe to their directly react to form sulfate or interact with CaCO 3 and BaCO 3 to form composite mineral heat-resistant in high temperature, but owe to their activation to sulfur-fixation reaction of the sulfur-fixation agent.
