摘要
具有高能量密度的锂硫电池有望成为下一代高性能电化学储能系统,但受限于其容量衰减较快的缺点,实用化过程仍存在较大困难。锂硫电池中存在的多硫化物中间产物"迁移效应"是导致容量快速衰减,系统库伦效率较低的重要原因之一。如何合理地控制锂硫电池系统中"迁移效应"的发生,仍是重要挑战。针对这一难题,本课题组提出在电池的隔膜系统中引入离子选择性功能层来提高电池的性能。通过引入离子选择层,可以在保留锂离子通道的同时阻止多硫化物的跨膜扩散,有效提升电池的库伦效率,循环稳定性,并降低电池的自放电速度。本课题组先后采用Nafion~([1]),氧化石墨烯隔膜(GO)~([2]),和聚丙烯/GO/Nafion三层隔膜系统~([3]),实现了多功能锂硫电池隔膜的构建。以Nafion层为例,其中的磺酸基团能充当锂离子跃迁通道实现锂离子的透过,且其荷电特性决定多硫阴离子无法跨膜扩散。引入Nafion层后,可将电池的单圈衰减率大幅降低至每圈0.08%以下。在三层隔膜系统中,利用超薄的GO层封闭大孔,超薄Nafion层实现离子选择,可在极低功能层负载量下同时实现高库伦效率,高循环稳定性和较高的倍率性能。这一方法将有助于构建实用化、高循环稳定性的锂硫电池系统。
Despite great effort devoted to solving the polysulfide shuttle between the cathode and anode electrodes,it remains as a serious challenge to build high-stable lithium sulfur battery,which related to the diffusion and reaction between polysulfides and the metal lithium anode.We proposed a strategy of introducing an ion selective membrane to improve the stability and Coulombic efficiency of lithium sulfur battery.By the introduction of permselective functional layer,the polysulfide anions can be confined in the cathode side,which would favor the cyclic stability and lower self-discharge performance.We demonstrated that Nafion and GO membrane can all serve as high efficient permselective layer on separator for Li-S batteries.With the rational design of PP/GO/Nafion ternary layered separator,even higher performance in Coulombic efficiency and high rate capability can be achieved at lower areal loading of the functional layer.Such ion selective membrane is versatile for various electrodes and working conditions,which is promising for the construction of high performance batteries.
引文
[1]Huang JQ,Zhang Q,Peng HJ,Liu XY,Qian WZ,Wei F.Energy Environ.Sci.2014,7:347.
[2]Huang JQ,Zhuang TZ,Zhang Q,Peng HJ,Chen CM,Wei F.ACS Nano.2015,9:3002.
[3]Zhuang TZ,Huang JQ,Peng HJ,He LY,Cheng XB,Chen CM,Zhang Q.Small.2016,12:381
