摘要
Currently,lithium-sulfur(Li-S)batteries still suffer from fast capacity decay,poor coulombic efficiency(CE)and short cycling lifespan,which result from the severe shuttle effect issue caused by high solubility and rapid diffusion of lithium polysulfides(Li PSs)in organic electrolytes.Here,yolk-shell zinc oxide(YSZn O)spheres are synthesized and for the first time,applied as a host for Li-S batteries to tackle this challenge.The polar Zn O exhibits high chemical anchoring ability toward Li PSs while the unique yolk-shell structure not only provides an additional physical barrier to Li PSs but also enables much more uniform sulfur distribution,thus significantly suppressing Li PSs shuttling effect meanwhile promoting sulfur conversion reactions.As a result,the YS-Zn O enables the Li-S battery to display an initial specific capacity of1355 m Ah g^(-1) and an outstanding capacity retention capability(~89.44%retention rate)even after 500 cycles with the average CE of~99.46%at the current of 0.5 C.By contrast,the capacity of conventional-Zn O-nanoparticles based battery severely decays to 472 m Ah g^(-1) after cycling for 500 times.More impressively,the S/YS-Zn O based Li-S battery can maintain a low decay rate of 0.040%every cycle and high average CE of 98.82%over 1000 cycles at 3 C.
基金
fully supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.T23-601/17-R)。
