Polyethylene oxide- Lithium bis ((trifluoromethyl)sulfonyl) azanide self-deposition on poly (m-phenylene isophthalamide) separator with sponge-like structure for boosting the electrochemical performance of Lithium-ion batteries

The key component that guarantees a stable cycle for lithium-ion batteries (LIBs) is the Solid Electrolyte Interphase (SEI) membrane, which possesses remarkable mechanical properties. A good SEI film can reduce the migration energy of Li + and support the even deposition of Li + onto the lithium anode. In this paper, polyethylene oxide (PEO)-Lithium bis((trifluoromethyl)sulfonyl) azanide (LiTFSI) was used as the surface modification layer of the poly ( m -phenylene isophthalamide) (PMIA) separator. The PEO-LiTFSI functional layer was applied onto the surface of PMIA separator through hydrogen bond interaction. The introduction of the PEO-LiTFSI functional layer promotes the interaction between the PMIA separator and the electrolyte, improves the porosity of separator, subsequently boosts the liquid absorption rate and electrolyte retention rate, and minimizes the migration resistance of Li + . PMIA/LiTFSI composite separator has a lower interface impedance (174.7 Ω). More importantly, the presence of LiTFSI leads to the development of a LiF-rich SEI film on the surface of lithium anode, which promotes the movement of Li + near the lithium anode and improves the structural stability of the SEI membrance, showing a longer service life of LIBs. Through long cycle test, it was found that the LFP||Li battery that employed the PMIA/LiTFSI composite separator still had a capacity retention rate of 95.4 % along with a specific discharge capacity of 133 mAh g −1 after undergoing 100 cycles.