一种多功能隔膜实现对多硫离子和锂离子的双重调控

Realizing dual regulation of polysulfides and lithium ions by a versatile separator

多硫离子穿梭和锂枝晶生长严重阻碍了锂硫电池的实际应用进程,而合理的隔膜结构可以达到一石二鸟的作用.本工作设计了一种携带有分散性TiN/CoO颗粒的氮掺杂碳纳米管结构(TCCNT),并将其用于锂硫电池隔膜修饰层.TCCNT的多孔结构和表面/内部携带的TiN/CoO颗粒不但实现了对多硫化物的物理、化学吸附和快速催化转化作用,其高导电性的空腔结构和亲锂作用还能够均化锂离子流,在5 mA cm^(-2)的电流密度下实现长达2000 h的均匀锂沉积/剥离过程.TCCNT合理的结构设计有利于各材料组分之间最大限度地发挥协同效应.采用改性隔膜所组装的锂硫电池在常规和高硫载量两种情况下均表现出较好的电化学性能,表明其具有一定的实际应用潜力.

Polysulfide shuttle and lithium dendrite growth severely limit the practical application of lithium-sulfur bat-teries(LSBs);however,a rational design of a separator can achieve the effect of two birds with one stone.Herein,nitro-gen-doped carbon nanotubes with dispersed TiN/CoO parti-cles(TCCNT)were designed and applied as a separator modification layer for LSBs.The porous structure of TCCNT can confine the diffusion of soluble polysulfides by physical adsorption first,and then the TiN/CoO particles carried on its surface/inside can not only further anchor the polysulfides via chemisorption but also act as a catalyst to facilitate their conversion.Meanwhile,the good lithophilicity of TiN was beneficial to homogenizing the Li+fluxes,guiding a uniform deposition of lithium and realizing a stable cycle of the lithium symmetric battery for up to 2000 h at 5 mA cm^(-2).Ascribed to the rational layout of the TCCNT layer that allows max-imization of the synergistic effect between various material components,an LSB equipped with a modified separator displayed satisfactory electrochemical performance in both cases of conventional and high sulfur loadings,demonstrating its practical application potential.