A novel fire safety separator decorated by Co2P/Co/C multifunctional layer for Li-S batteries

Lithium-Sulfur (Li-S) battery is a potential alternative energy storage system owing to its high theoretical capacity, low cost, and eco-friendly features. However, the commercialization of Li-S battery has been hindered by the notorious shuttle effect. To overcome the above-mentioned long-standing problem, herein, an advanced separator modified by N and P heteroatoms co-doped carbon frameworks with con-fined Co2P nanoparticles (named Co2P/Co/C) has been successfully prepared. The introduction of functional coating can obviously enhance the thermal stability of separator. To be specific, it showed higher initial decomposition temperature (475) and lower maximum mass loss rate (1.755% 1) values than the Celgard separator (400 and 2.915% 1, respectively). Notably, when kindled separators directly, the modified separator can quench by itself with many residual remains. In addition, the engineered functional layer possesses the capability of capturing lithium polysulfides (LiPSs), and then confines them within the cathode region so that the shuttle effect can be restrained effectively. After assembling the modified separator in the Li-S cell, compared with the cell with Celgard separator of low initial specific discharge capacity (730 mAh g(-1)), the cell with Co2P/Co/C separator delivered a superior initial discharge capacity of 1310 mAh g(-1) at 0.5 C. Also, the modified cell can perform remarkably enhanced rate performances. In addition, As a consequence of these merits, the modified separator with improved thermal stability, preferable fire safety, and satisfied electrochemical performances shows significant guiding value for advancing the practical application of Li-S batteries. (C) 2022 Published by Elsevier B.V.

Automated summary

In this study, an advanced separator modified with N and P heteroatoms co-doped carbon frameworks was successfully prepared. The modified separator showed improved thermal stability, fire safety, and restrained shuttle effect in lithium-sulfur batteries, leading to enhanced discharge capacity and rate performances. These findings are of significant importance for the practical application of Li-S batteries.