The popularity of lithium–sulfur batteries has been increasing gradually due to their ultrahigh theoretical specific capacity and energy density. Nevertheless, they also have lots of drawbacks to be overcome, such as...The popularity of lithium–sulfur batteries has been increasing gradually due to their ultrahigh theoretical specific capacity and energy density. Nevertheless, they also have lots of drawbacks to be overcome, such as poor conductivity, severe volume expansion, and serious“shuttle effect”. In this work, reduced graphene oxide/molybdenum dioxide(rGO/MoO_(2)) composite is synthesized and applied to modify polypropylene separator. The modified polypropylene separator introduces synergistic tri-functions of physical adsorption, chemical interaction and catalytic effects, which can inhibit the“shuttle effect” and enhance the electrochemical performances of lithium-sulfur batteries. In the prepared r GO/MoO_(2) composite, the polar MoO_(2) chemically adsorbs the intermediate lithium polysulfide, while the rGO with good electrical conductivity not only acts as a physical barrier to prevent diffusion of polysulfide ions, but also improves the conversion efficiency of active material intercepted on the separator. As a consequence, the battery assembled with rGO/MoO_(2) modified polypropylene separator exhibits a reversible capacity of 757.5 mAh·g^(-1) after 200 cycles at0.2 C with a negligible capacity decay of 0.207% per cycle,which indicates a good long-period cycling stability. Furthermore, the rate performance and self-discharge suppression are also improved by introducing modified polypropylene separator. It shows that rGO/MoO_(2) composite is a promising material for separator modification in lithium-sulfur batteries.展开更多
Lithium-sulfur(Li-S)batteries have great potential as the next generation of high-energy-density storage systems.However,the practical viability of Li-S batteries is largely hampered by undesirable shuttling behavior ...Lithium-sulfur(Li-S)batteries have great potential as the next generation of high-energy-density storage systems.However,the practical viability of Li-S batteries is largely hampered by undesirable shuttling behavior and sluggish conversion kinetics of polysulfides.Herein,a multifunctional separatormodified layer(In/Zr-BTB nanosheets)with the merits of robust structures and efficient catalytic metal sites has been presented.In/Zr-BTB nanosheets inherit the stable structure from Zr-BTB and strengthen the catalytic performance due to the introduction of highly catalytic species indium via metal-ion exchange.The thickness and areal mass loading of the modified layer are only 260 nm and 0.011 mg/cm2,respectively.Nevertheless,the ultrathin modification layers with efficient catalytic species,compact structures,and uniform pore channels can realize fast Li+transport,effective polysulfide interception,and rapid catalytic conversion.Therefore,the In/Zr-BTB@PP cell with a high sulfur content of 80 wt%could maintain high capacity retention of 85.6%with a low capacity fading rate of 0.048%per cycle after 300 cycles even at a high current rate of 2 C.This work opens a new door toward the design of versatile metal-organic framework(MOF)nanosheets and multifunctional separators for high-energy-density Li-S batteries.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.21606065 and 21676067)Anhui Provincial Natural Science Foundation (Nos.1708085QE98 and 1908085QE178)+1 种基金the Fundamental Research Funds for the Central Universities (Nos.JZ2017YYPY0253,JZ2017HGTB0198,JZ2018HGBZ0138 and PA2020GDGP0054)the Opening Project of CAS Key Laboratory of Materials for Energy Conversion (No.KF2018003)。
文摘The popularity of lithium–sulfur batteries has been increasing gradually due to their ultrahigh theoretical specific capacity and energy density. Nevertheless, they also have lots of drawbacks to be overcome, such as poor conductivity, severe volume expansion, and serious“shuttle effect”. In this work, reduced graphene oxide/molybdenum dioxide(rGO/MoO_(2)) composite is synthesized and applied to modify polypropylene separator. The modified polypropylene separator introduces synergistic tri-functions of physical adsorption, chemical interaction and catalytic effects, which can inhibit the“shuttle effect” and enhance the electrochemical performances of lithium-sulfur batteries. In the prepared r GO/MoO_(2) composite, the polar MoO_(2) chemically adsorbs the intermediate lithium polysulfide, while the rGO with good electrical conductivity not only acts as a physical barrier to prevent diffusion of polysulfide ions, but also improves the conversion efficiency of active material intercepted on the separator. As a consequence, the battery assembled with rGO/MoO_(2) modified polypropylene separator exhibits a reversible capacity of 757.5 mAh·g^(-1) after 200 cycles at0.2 C with a negligible capacity decay of 0.207% per cycle,which indicates a good long-period cycling stability. Furthermore, the rate performance and self-discharge suppression are also improved by introducing modified polypropylene separator. It shows that rGO/MoO_(2) composite is a promising material for separator modification in lithium-sulfur batteries.
基金support by the National Natural Science Foundation of China(grant nos.22005054,22101048,21805039,21971038,and 21975044)Natural Science Foundation of Fujian Province(grant no.2021J01149)State Key Laboratory of Structural Chemistry(grant no.20200007).
文摘Lithium-sulfur(Li-S)batteries have great potential as the next generation of high-energy-density storage systems.However,the practical viability of Li-S batteries is largely hampered by undesirable shuttling behavior and sluggish conversion kinetics of polysulfides.Herein,a multifunctional separatormodified layer(In/Zr-BTB nanosheets)with the merits of robust structures and efficient catalytic metal sites has been presented.In/Zr-BTB nanosheets inherit the stable structure from Zr-BTB and strengthen the catalytic performance due to the introduction of highly catalytic species indium via metal-ion exchange.The thickness and areal mass loading of the modified layer are only 260 nm and 0.011 mg/cm2,respectively.Nevertheless,the ultrathin modification layers with efficient catalytic species,compact structures,and uniform pore channels can realize fast Li+transport,effective polysulfide interception,and rapid catalytic conversion.Therefore,the In/Zr-BTB@PP cell with a high sulfur content of 80 wt%could maintain high capacity retention of 85.6%with a low capacity fading rate of 0.048%per cycle after 300 cycles even at a high current rate of 2 C.This work opens a new door toward the design of versatile metal-organic framework(MOF)nanosheets and multifunctional separators for high-energy-density Li-S batteries.
