Polyimine represents a rapidly emerging class of readily accessible and affordable covalent adaptable networks(CANs)that have been extensively studied in the past few years.While being highly malleable and recyclable,...Polyimine represents a rapidly emerging class of readily accessible and affordable covalent adaptable networks(CANs)that have been extensively studied in the past few years.While being highly malleable and recyclable,the pioneering polyimine materials are relatively soft and not suitable for certain applications that require high mechanical performance.Recent studies have demonstrated the possibility of significantly improving polyimine properties by varying its monomer building blocks,but such component variations are usually not straightforward and can be potentially challenging and costly.Herein,we report an in situ oxidation polymerization strategy for preparation of mechanically strong poly(imine-amide)(PIA)hybrid CANs from simple amine and aldehyde monomers.By converting a portion of reversible imine bonds into high-strength amide linkages in situ,the obtained hybrid materials exhibit gradually improved Young’s modulus and ultimate tensile strength as the oxidation level increased.Meanwhile,the PIAs remain reprocessable and can be depolymerized into small molecules and oligomers similar as polyimine.This work demonstrates the great potential of the in situ transformation strategy as a new approach for development of various mechanically tunable CANs from the same starting building blocks.展开更多
Separator modification represents a critical strategy for addressing the challenges in lithium-ion batteries(LIBs),including restricted Li^(+) transport,poor interfacial stability,and safety risks.Using functional coa...Separator modification represents a critical strategy for addressing the challenges in lithium-ion batteries(LIBs),including restricted Li^(+) transport,poor interfacial stability,and safety risks.Using functional coatings has emerged as an effective approach for enhancing separator performance without altering the bulk structure of the separators.Herein,we report the first example of ethynylene-linked conjugated microporous polymers(CMPs)for LIB separator modification.Specifically,two CMPs substituted with different groups(fluorine for CMP-F and methyl for CMP-CH_(3))were synthesized through dynamic alkyne metathesis and applied as functional coatings on polyethylene(PE)separators.The ethynylene-linked backbone structure,along with the introduction of electron-withdrawing fluorine atoms,endows the CMPs with high electron density,hence reducing Li^(+) binding and solvent interactions,lowering the desolvation energy barrier at the electrolyte-separator interface,and facilitating Li^(+) transport.The fluorine could also act as hopping sites to facilitate Li^(+) conduction.We demonstrated through full-cell evaluations using graphite anodes and NMC532 cathodes that CMP-F@PE separators significantly improve both the rate performance and cycling stability.Furthermore,the CMP-F@PE separators also exhibited outstanding thermal stability,thereby improving battery safety.These results highlight the great potential of ethynylene-linked CMPs as structurally tunable,superior-performance,high-efficiency separator coatings for next-generation LIBs.展开更多
基金the University of Colorado Boulder and the National Science Foundation (No. 49100423C0008, Y.J.) for financial support
文摘Polyimine represents a rapidly emerging class of readily accessible and affordable covalent adaptable networks(CANs)that have been extensively studied in the past few years.While being highly malleable and recyclable,the pioneering polyimine materials are relatively soft and not suitable for certain applications that require high mechanical performance.Recent studies have demonstrated the possibility of significantly improving polyimine properties by varying its monomer building blocks,but such component variations are usually not straightforward and can be potentially challenging and costly.Herein,we report an in situ oxidation polymerization strategy for preparation of mechanically strong poly(imine-amide)(PIA)hybrid CANs from simple amine and aldehyde monomers.By converting a portion of reversible imine bonds into high-strength amide linkages in situ,the obtained hybrid materials exhibit gradually improved Young’s modulus and ultimate tensile strength as the oxidation level increased.Meanwhile,the PIAs remain reprocessable and can be depolymerized into small molecules and oligomers similar as polyimine.This work demonstrates the great potential of the in situ transformation strategy as a new approach for development of various mechanically tunable CANs from the same starting building blocks.
文摘Separator modification represents a critical strategy for addressing the challenges in lithium-ion batteries(LIBs),including restricted Li^(+) transport,poor interfacial stability,and safety risks.Using functional coatings has emerged as an effective approach for enhancing separator performance without altering the bulk structure of the separators.Herein,we report the first example of ethynylene-linked conjugated microporous polymers(CMPs)for LIB separator modification.Specifically,two CMPs substituted with different groups(fluorine for CMP-F and methyl for CMP-CH_(3))were synthesized through dynamic alkyne metathesis and applied as functional coatings on polyethylene(PE)separators.The ethynylene-linked backbone structure,along with the introduction of electron-withdrawing fluorine atoms,endows the CMPs with high electron density,hence reducing Li^(+) binding and solvent interactions,lowering the desolvation energy barrier at the electrolyte-separator interface,and facilitating Li^(+) transport.The fluorine could also act as hopping sites to facilitate Li^(+) conduction.We demonstrated through full-cell evaluations using graphite anodes and NMC532 cathodes that CMP-F@PE separators significantly improve both the rate performance and cycling stability.Furthermore,the CMP-F@PE separators also exhibited outstanding thermal stability,thereby improving battery safety.These results highlight the great potential of ethynylene-linked CMPs as structurally tunable,superior-performance,high-efficiency separator coatings for next-generation LIBs.
