Metal-organic nanosheets(MONs)as a novel material with tunable pore structures and low mass transfer resistance,have emerged as molecular sieves for the separation of gases and liquids.In theory,they can also serve as...Metal-organic nanosheets(MONs)as a novel material with tunable pore structures and low mass transfer resistance,have emerged as molecular sieves for the separation of gases and liquids.In theory,they can also serve as ion sieves for lithium metal batteries(LMBs),realizing the high-energy and dendritic free LMBs.However,there are rarely relevant reports,because it is difficult to simultaneously balance efficient ion sieving ability,high ion passing rate and high electrochemical stability.Here,we synthesized a stable ultrathin MON[Zn_(2)(Bim)_(4)]([Zn_(2)(Bim)_(4)]Nanosheet,HBim=benzimidazolate),which can achieve both efficient lithium ion sieving ability,high lithium ion passing rate and high electrochemical stability at the same time.The separator assembled by this MON exhibits high Li^(+)transfer number of 0.81 due to the accurate lithium ion and anion/solvent separation.The battery containing such separator shows high lithium ionic conductivity of 0.74 m S cm^(-1)and low activation energy of 0.099 eV,which can be attributed to the nanometer level thickness and the ion sieving effect.What is more,we realized the application of MONs-based ion sieves in LMBs with intercalation cathodes for the first time.And the LiFePO_(4)|Li battery with as-assembled separator demonstrates improved Coulombic efficiency(>99%)and significantly extended cycling life(>1600 cycles)with 80%capacity retention.展开更多
There is an urgent need to break through the trade-off between proton conductivity and ion selectivity of proton exchange membrane(PEM)in vanadium flow battery(VFB).Proton channels in PEM are the key to controlling th...There is an urgent need to break through the trade-off between proton conductivity and ion selectivity of proton exchange membrane(PEM)in vanadium flow battery(VFB).Proton channels in PEM are the key to controlling the ion sieving and proton conductivity in VFB.Herein,two types of proton channels are reconstructed in the hybrid membrane via introducing modified Zr-MOFs(IM-UIO-66-AS)into SPEEK matrix.Internal proton channels in IM-UIO-66-AS and interfacial proton channels between grafted imidazole groups on Zr-MOFs and SPEEK greatly improve the conductivity of the IM-UIO-66-AS/SPEEK hybrid membrane.More importantly,both reconstructed proton channels block the vanadium-ion permeation to realize enhanced ion selectivity according to the size sieving and Donnan exclusion effects,respectively.Moreover,the hybrid membrane exhibits good mechanical property and dimensional stability.Benefiting from such rational design,a VFB loading with the optimized membrane exhibits enhanced voltage efficiency of 79.9%and outstanding energy efficiency of 79.6%at 200 m A cm^(-2),and keeps a notable cycle stability for 300 cycles in the long-term cycling test.Therefore,this study provides inspiration for preparing next-generation PEMs with high ion selectivity and proton conductivity for VFB application.展开更多
Surface chemical modification of polyolefin separators for lithium ion batteries is attempted to reduce the thermal shrinkage, which is im- portant for the battery energy density. In this study, we grafted organic/ino...Surface chemical modification of polyolefin separators for lithium ion batteries is attempted to reduce the thermal shrinkage, which is im- portant for the battery energy density. In this study, we grafted organic/inorganic hybrid crosslinked networks on the separators, simply by grafting polymerization and condensation reaction. The considerable silicon-oxygen crosslinked heat-resistance networks are responsible for the reduced thermal shrinkage. The strong chemical bonds between networks and separators promise enough mechanical support even at high temperature. The shrinkage at 150 ℃ for 30 min in the mechanical direction was 38.6% and 4.6% for the pristine and present graft-modified separators, respectively. Meanwhile, the grafting organic-inorganic hybrid crosslink networks mainly occupied part of void in the internal pores of the separators, so the thicknesses of the graft-modified separators were similar with the pristine one. The half cells prepared with the modified separators exhibited almost identical electrochemical properties to those with the commercial separators, thus proving that, in order to enhance the thermal stability of lithium ion battery, this kind of grafting-modified separators may be a better alternative to conventional silica nanoparticle layers-coated polyolefin separators.展开更多
锂离子混合电容器由于兼备锂离子电池和超级电容器的优势,即较高的能量密度和功率密度,而成为当前能量存储体系的研究热点。本工作合成了具有三维花状微纳结构的正交相五氧化二铌(T-Nb_2O_5),并将其与活性炭(AC)相匹配,设计出一种新型的...锂离子混合电容器由于兼备锂离子电池和超级电容器的优势,即较高的能量密度和功率密度,而成为当前能量存储体系的研究热点。本工作合成了具有三维花状微纳结构的正交相五氧化二铌(T-Nb_2O_5),并将其与活性炭(AC)相匹配,设计出一种新型的T-Nb_2O_5/AC锂离子混合电容器。循环伏安和恒电流充放电的测试结果表明该锂离子混合电容器具有较好的电化学性能,如在碳酸酯类的有机电解液中,工作电压可达到3.0 V;在100 m A·g^(-1)的电流密度下,电容器的比能量和比功率密度可达到53.79 Wh·kg^(-1)和294 W·kg^(-1);在200 m A·g^(-1)的电流密度下,经过1000次充放电循环后,该电容器的比能量保持率为73%。由此可见,本工作开发的T-Nb_2O_5/AC锂离子混合电容器将在高功率的储能设备中有很好地应用前景。展开更多
基金the financial support of the Natural Science Foundation of Shanxi Province(20210302124055)the National Natural Science Foundation of China(22301170,22271211 and 91961201)1331 Project of Shanxi Province。
文摘Metal-organic nanosheets(MONs)as a novel material with tunable pore structures and low mass transfer resistance,have emerged as molecular sieves for the separation of gases and liquids.In theory,they can also serve as ion sieves for lithium metal batteries(LMBs),realizing the high-energy and dendritic free LMBs.However,there are rarely relevant reports,because it is difficult to simultaneously balance efficient ion sieving ability,high ion passing rate and high electrochemical stability.Here,we synthesized a stable ultrathin MON[Zn_(2)(Bim)_(4)]([Zn_(2)(Bim)_(4)]Nanosheet,HBim=benzimidazolate),which can achieve both efficient lithium ion sieving ability,high lithium ion passing rate and high electrochemical stability at the same time.The separator assembled by this MON exhibits high Li^(+)transfer number of 0.81 due to the accurate lithium ion and anion/solvent separation.The battery containing such separator shows high lithium ionic conductivity of 0.74 m S cm^(-1)and low activation energy of 0.099 eV,which can be attributed to the nanometer level thickness and the ion sieving effect.What is more,we realized the application of MONs-based ion sieves in LMBs with intercalation cathodes for the first time.And the LiFePO_(4)|Li battery with as-assembled separator demonstrates improved Coulombic efficiency(>99%)and significantly extended cycling life(>1600 cycles)with 80%capacity retention.
基金supported by the National Natural Science Foundation of China(Grant No.21975267)the Central Guidance on Local Science and Technology Development Fund of Liaoning Province(No:2022JH6/100100001)。
文摘There is an urgent need to break through the trade-off between proton conductivity and ion selectivity of proton exchange membrane(PEM)in vanadium flow battery(VFB).Proton channels in PEM are the key to controlling the ion sieving and proton conductivity in VFB.Herein,two types of proton channels are reconstructed in the hybrid membrane via introducing modified Zr-MOFs(IM-UIO-66-AS)into SPEEK matrix.Internal proton channels in IM-UIO-66-AS and interfacial proton channels between grafted imidazole groups on Zr-MOFs and SPEEK greatly improve the conductivity of the IM-UIO-66-AS/SPEEK hybrid membrane.More importantly,both reconstructed proton channels block the vanadium-ion permeation to realize enhanced ion selectivity according to the size sieving and Donnan exclusion effects,respectively.Moreover,the hybrid membrane exhibits good mechanical property and dimensional stability.Benefiting from such rational design,a VFB loading with the optimized membrane exhibits enhanced voltage efficiency of 79.9%and outstanding energy efficiency of 79.6%at 200 m A cm^(-2),and keeps a notable cycle stability for 300 cycles in the long-term cycling test.Therefore,this study provides inspiration for preparing next-generation PEMs with high ion selectivity and proton conductivity for VFB application.
基金supported by the MOST(Grant No.2013CB934000,2014DFG71590,2011CB935902,2010DFA72760,2011CB711202,2013AA050903,2011AA11A257 and 2011AA11A254)China Postdoctoral Science Foundation(Grant No.2013M530599 and 2013M540929)+2 种基金Tsinghua University Initiative Scientific Research Program(Grant No.2010THZ08116,2011THZ08139,2011THZ01004 and 2012THZ08129)the State Key Laboratory of Automotive Safety and Energy(No.ZZ2012-011)Suzhou(Wujiang)Automotive Research Institute,Tsinghua University,Project No.2012WJ-A-01
文摘Surface chemical modification of polyolefin separators for lithium ion batteries is attempted to reduce the thermal shrinkage, which is im- portant for the battery energy density. In this study, we grafted organic/inorganic hybrid crosslinked networks on the separators, simply by grafting polymerization and condensation reaction. The considerable silicon-oxygen crosslinked heat-resistance networks are responsible for the reduced thermal shrinkage. The strong chemical bonds between networks and separators promise enough mechanical support even at high temperature. The shrinkage at 150 ℃ for 30 min in the mechanical direction was 38.6% and 4.6% for the pristine and present graft-modified separators, respectively. Meanwhile, the grafting organic-inorganic hybrid crosslink networks mainly occupied part of void in the internal pores of the separators, so the thicknesses of the graft-modified separators were similar with the pristine one. The half cells prepared with the modified separators exhibited almost identical electrochemical properties to those with the commercial separators, thus proving that, in order to enhance the thermal stability of lithium ion battery, this kind of grafting-modified separators may be a better alternative to conventional silica nanoparticle layers-coated polyolefin separators.
文摘锂离子混合电容器由于兼备锂离子电池和超级电容器的优势,即较高的能量密度和功率密度,而成为当前能量存储体系的研究热点。本工作合成了具有三维花状微纳结构的正交相五氧化二铌(T-Nb_2O_5),并将其与活性炭(AC)相匹配,设计出一种新型的T-Nb_2O_5/AC锂离子混合电容器。循环伏安和恒电流充放电的测试结果表明该锂离子混合电容器具有较好的电化学性能,如在碳酸酯类的有机电解液中,工作电压可达到3.0 V;在100 m A·g^(-1)的电流密度下,电容器的比能量和比功率密度可达到53.79 Wh·kg^(-1)和294 W·kg^(-1);在200 m A·g^(-1)的电流密度下,经过1000次充放电循环后,该电容器的比能量保持率为73%。由此可见,本工作开发的T-Nb_2O_5/AC锂离子混合电容器将在高功率的储能设备中有很好地应用前景。
基金Qinghai Science&Technology Projects(2016-GX-102)Youth Innovation Promotion Association CAS(2016376)Open project of State Key Laboratory of Chemical Resource Engineering(CRE-2017-c-202)
