Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.He...Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.Herein,a separator with multifunctional layers composed of N-doped mesoporous hollow carbon spheres(HCS)as the inner layer and sodium fluoride(NaF)as the outer layer on commercial polypropylene separator(PP)is proposed(PP@HCS-NaF)to achieve stable cycling in SMB.At the molecular level,the inner HCS layer with a high content of pyrrolic-N induces the uniform Na^(+)flux as a potential Na^(+)redistributor for homogenous deposition,whereas its hollow mesoporous structure offers nanoporous buffers and ion channels to regulate Na^(+)ion distribution and uniform deposition.The outer layer(NaF)constructs the NaF-enriched robust solid electrolyte interphase layer,significantly lowering the Na^(+)ions diffusion barrier.Benefiting from these merits,higher electrochemical performances are achieved with multifunctional double-layered PP@HCS-NaF separators compared with single-layered separators(i.e.PP@HCS or PP@NaF)in SMBs.The Na‖Cu half-cell with PP@HCS-NaF offers stable cycling(280 cycles)with a high CE(99.6%),and Na‖Na symmetric cells demonstrate extended lifespans for over 6000 h at 1 mA cm^(-2)with a progressively stable overpotential of 9 mV.Remarkably,in Na‖NVP full-cells,the PP@HCS-NaF separator grants a stable capacity of~81 mA h g^(-1)after 3500 cycles at 1 C and an impressive rate capability performance(~70 mA h g^(-1)at 15 C).展开更多
基金supported by the National Natural Science Foundation of China(Grant Number 22350410379)Zhejiang Provincial Natural Science Foundation of China(LZ23B030003)+1 种基金the Fundamental Research Funds for the Central Universities(226-202400075)Ten Thousand Talent Program of Zhejiang Province.
文摘Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.Herein,a separator with multifunctional layers composed of N-doped mesoporous hollow carbon spheres(HCS)as the inner layer and sodium fluoride(NaF)as the outer layer on commercial polypropylene separator(PP)is proposed(PP@HCS-NaF)to achieve stable cycling in SMB.At the molecular level,the inner HCS layer with a high content of pyrrolic-N induces the uniform Na^(+)flux as a potential Na^(+)redistributor for homogenous deposition,whereas its hollow mesoporous structure offers nanoporous buffers and ion channels to regulate Na^(+)ion distribution and uniform deposition.The outer layer(NaF)constructs the NaF-enriched robust solid electrolyte interphase layer,significantly lowering the Na^(+)ions diffusion barrier.Benefiting from these merits,higher electrochemical performances are achieved with multifunctional double-layered PP@HCS-NaF separators compared with single-layered separators(i.e.PP@HCS or PP@NaF)in SMBs.The Na‖Cu half-cell with PP@HCS-NaF offers stable cycling(280 cycles)with a high CE(99.6%),and Na‖Na symmetric cells demonstrate extended lifespans for over 6000 h at 1 mA cm^(-2)with a progressively stable overpotential of 9 mV.Remarkably,in Na‖NVP full-cells,the PP@HCS-NaF separator grants a stable capacity of~81 mA h g^(-1)after 3500 cycles at 1 C and an impressive rate capability performance(~70 mA h g^(-1)at 15 C).
