Glass-fiber-reinforced polymeric film as an efficient protecting layer for stable Li metal electrodes

Abstract

With numerous reports on protecting films for stable lithium (Li) metal electrodes, the key attributes for how to construct these efficient layers have rarely been fully investigated. Here, we report a rationally designed hybrid protective layer (HPL) with each component aligning with one key attribute; i.e., cross-linked poly(dimethylsiloxane) (PDMS) enhances flexibility, polyethylene glycol (PEG) provides homogeneous ion-conducting channels, and glass fiber (GF) affords mechanical robustness. A significant improvement of the electrochemical performance of HPL-modified electrodes can be achieved in Li/HPL@Cu half cells, HPL@Li/HPL@Li symmetric cells, and HPL@Li/LiFePO 4 full cells. Even with an industrial standard LiFePO 4 cathode (96.8 wt % active material), the assembled cell still exhibits a capacity retention of 90% after 100 cycles at 1 C. More importantly, the functionality of each component has been studied comprehensively via electrochemical and physical experiments and simulations, which will provide useful guidance on how to construct efficient protective layers for next-generation energy storage devices. • Rationally designed hybrid protective films achieve ultra-stable Li metal electrode • Investigation of the individual role of each component in designed protective films • The key attributes of efficient protecting layers are unraveled. Gao et al. report a rationally designed multi-component hybrid protective film. Careful investigation of the role of each component in the hybrid protective film reveals the key attributes required to achieve an efficient protective layer for Li metal batteries with improved electrochemical performance.