Despite the presence of Li F components in the solid electrolyte interphase(SEI)formed on the graphite anode surface by conventional electrolyte,these Li F components primarily exist in an amorphous state,rendering th...Despite the presence of Li F components in the solid electrolyte interphase(SEI)formed on the graphite anode surface by conventional electrolyte,these Li F components primarily exist in an amorphous state,rendering them incapable of effectively inhibiting the exchange reaction between lithium ions and transition metal ions in the electrolyte.Consequently,nearly all lithium ions within the SEI film are replaced by transition metal ions,resulting in an increase in interphacial impedance and a decrease in stability.Herein,we demonstrate that the SEI film,constructed by fluoroethylene carbonate(FEC)additive rich in crystalline Li F,effectively inhibits the undesired Li^(+)/Co^(2+)ion exchange reaction,thereby suppressing the deposition of cobalt compounds and metallic cobalt.Furthermore,the deposited cobalt compounds exhibit enhanced structural stability and reduced catalytic activity with minimal impact on the interphacial stability of the graphite anode.Our findings reveal the crucial influence of SEI film composition and structure on the deposition and hazards associated with transition metal ions,providing valuable guidance for designing next-generation electrolytes.展开更多
Existing specific emitter identification(SEI)methods based on hand-crafted features have drawbacks of losing feature information and involving multiple processing stages,which reduce the identification accuracy of emi...Existing specific emitter identification(SEI)methods based on hand-crafted features have drawbacks of losing feature information and involving multiple processing stages,which reduce the identification accuracy of emitters and complicate the procedures of identification.In this paper,we propose a deep SEI approach via multidimensional feature extraction for radio frequency fingerprints(RFFs),namely,RFFsNet-SEI.Particularly,we extract multidimensional physical RFFs from the received signal by virtue of variational mode decomposition(VMD)and Hilbert transform(HT).The physical RFFs and I-Q data are formed into the balanced-RFFs,which are then used to train RFFsNet-SEI.As introducing model-aided RFFs into neural network,the hybrid-driven scheme including physical features and I-Q data is constructed.It improves physical interpretability of RFFsNet-SEI.Meanwhile,since RFFsNet-SEI identifies individual of emitters from received raw data in end-to-end,it accelerates SEI implementation and simplifies procedures of identification.Moreover,as the temporal features and spectral features of the received signal are both extracted by RFFsNet-SEI,identification accuracy is improved.Finally,we compare RFFsNet-SEI with the counterparts in terms of identification accuracy,computational complexity,and prediction speed.Experimental results illustrate that the proposed method outperforms the counterparts on the basis of simulation dataset and real dataset collected in the anechoic chamber.展开更多
Compared with graphite,the lower sodiation potential and larger discharge capacity of hard carbon(HC)makes it the most promising anode material for sodium-ion battery.Utilizing ether-based electrolyte rather than conv...Compared with graphite,the lower sodiation potential and larger discharge capacity of hard carbon(HC)makes it the most promising anode material for sodium-ion battery.Utilizing ether-based electrolyte rather than conventional carbonate-based electrolyte,HC achieves superior electrochemical performance.Nevertheless,the mechanism by which ether-based electrolyte improves the properties of HC is still controversial,primarily focusing on whether it forms solid electrolyte interphase(SEI)film.In this work,according to the sodium storage mechanisms in HC at low voltage(<0.1 V),including Na^(+)-diglyme co-interaction into the carbon layer(SEI forbidden)and desolvated Na^(+)insertion in the irregular carbon holes(SEI required),the NaPF6concentration in ether-based electrolyte was regulated,so as to construct a discontinuous-SEI on the surface of the HC anode,which significantly enhances the electrochemical performances of HC.Specifically,with 0.2 M NaPF6ether-based electrolyte,HC deliverers a discharge capacity of 459.7 mA h g^(-1)at 0.1 C and stays at 357.2 mA h g^(-1)after 500 cycles at 1 C,which is substantially higher than that of higher/lower salt concentration electrolytes.展开更多
基金supported by the National Natural Science Foundation of China(21972049,21573080)。
文摘Despite the presence of Li F components in the solid electrolyte interphase(SEI)formed on the graphite anode surface by conventional electrolyte,these Li F components primarily exist in an amorphous state,rendering them incapable of effectively inhibiting the exchange reaction between lithium ions and transition metal ions in the electrolyte.Consequently,nearly all lithium ions within the SEI film are replaced by transition metal ions,resulting in an increase in interphacial impedance and a decrease in stability.Herein,we demonstrate that the SEI film,constructed by fluoroethylene carbonate(FEC)additive rich in crystalline Li F,effectively inhibits the undesired Li^(+)/Co^(2+)ion exchange reaction,thereby suppressing the deposition of cobalt compounds and metallic cobalt.Furthermore,the deposited cobalt compounds exhibit enhanced structural stability and reduced catalytic activity with minimal impact on the interphacial stability of the graphite anode.Our findings reveal the crucial influence of SEI film composition and structure on the deposition and hazards associated with transition metal ions,providing valuable guidance for designing next-generation electrolytes.
基金supported by the National Natural Science Foundation of China(62061003)Sichuan Science and Technology Program(2021YFG0192)+1 种基金the Research Foundation of the Civil Aviation Flight University of China(ZJ2020-04J2020-033)。
文摘Existing specific emitter identification(SEI)methods based on hand-crafted features have drawbacks of losing feature information and involving multiple processing stages,which reduce the identification accuracy of emitters and complicate the procedures of identification.In this paper,we propose a deep SEI approach via multidimensional feature extraction for radio frequency fingerprints(RFFs),namely,RFFsNet-SEI.Particularly,we extract multidimensional physical RFFs from the received signal by virtue of variational mode decomposition(VMD)and Hilbert transform(HT).The physical RFFs and I-Q data are formed into the balanced-RFFs,which are then used to train RFFsNet-SEI.As introducing model-aided RFFs into neural network,the hybrid-driven scheme including physical features and I-Q data is constructed.It improves physical interpretability of RFFsNet-SEI.Meanwhile,since RFFsNet-SEI identifies individual of emitters from received raw data in end-to-end,it accelerates SEI implementation and simplifies procedures of identification.Moreover,as the temporal features and spectral features of the received signal are both extracted by RFFsNet-SEI,identification accuracy is improved.Finally,we compare RFFsNet-SEI with the counterparts in terms of identification accuracy,computational complexity,and prediction speed.Experimental results illustrate that the proposed method outperforms the counterparts on the basis of simulation dataset and real dataset collected in the anechoic chamber.
基金supported by the National Natural Science Foundation of China(No.21972049)。
文摘Compared with graphite,the lower sodiation potential and larger discharge capacity of hard carbon(HC)makes it the most promising anode material for sodium-ion battery.Utilizing ether-based electrolyte rather than conventional carbonate-based electrolyte,HC achieves superior electrochemical performance.Nevertheless,the mechanism by which ether-based electrolyte improves the properties of HC is still controversial,primarily focusing on whether it forms solid electrolyte interphase(SEI)film.In this work,according to the sodium storage mechanisms in HC at low voltage(<0.1 V),including Na^(+)-diglyme co-interaction into the carbon layer(SEI forbidden)and desolvated Na^(+)insertion in the irregular carbon holes(SEI required),the NaPF6concentration in ether-based electrolyte was regulated,so as to construct a discontinuous-SEI on the surface of the HC anode,which significantly enhances the electrochemical performances of HC.Specifically,with 0.2 M NaPF6ether-based electrolyte,HC deliverers a discharge capacity of 459.7 mA h g^(-1)at 0.1 C and stays at 357.2 mA h g^(-1)after 500 cycles at 1 C,which is substantially higher than that of higher/lower salt concentration electrolytes.
