A tailored ceramic composite separator with electron-rich groups for high-performance lithium metal anode.

Ceramic composite separator is more competitive than traditional polyolefin separator in the field of power supply for superior thermal stability and wettability of liquid electrolyte. In this study, we develop a two-steps method that modifies SiO 2 with acrylamide (AM) by grafting process and prepare a functional SiO 2 composite separator (PE/SiO 2 -AM). This kind of composite separator exhibits similar size-shrinkage (8.8%) to that of PE/SiO 2 composite separator at the tested temperature, lower than 18.1% of bare PE separator, and is electrochemically stable below 4.5 V (vs. Li/Li+). In addition, the Li-symmetric cells employing PE/SiO 2 -AM composite separator have the lowest overpotential and an improved lithium-ion transference number of 0.44. It is demonstrated from DFT calculation that the electron-rich species of imide group is able to uniformly disperse lithium-ion flux at the interface of electrolyte/lithium anode, and contributes to lithium-ion transport process. After assembling the LiCoO 2 /Li half cells, the cell with PE/SiO 2 -AM composite separator displays better cycle performance and higher discharge capacity when compared with other separators. Therefore, functional ceramic separator would be more attractive for next-generation lithium metal battery with high energy density. The functional coat is a superior strategy to optimize the interface among the lithium metal anode, separator and liquid electrolyte. In our study, we have synthesized uniform-size SiO 2 particles and have modified their surface with acrylamide (AM) by a bridge media of vinyl trimethoxysilane (VTMS). AM is a kind of monomer with negative charge property, which is able to stabilize the distribution of lithium-ion at this interface of electrolyte/electrode and affect the space charge layer (C d). This enhanced space charge layer can facilitate the conduction of Li+ (X c = 1/(2πC d)). [Display omitted] • A functional SiO 2 composite separator with imide group (PE/SiO 2 -AM) was prepared. • PE/SiO 2 -AM composite separator exhibits the smallest size-shrinkage separator. • PE/SiO 2 -AM composite separator possesses an improved lithium-ion transference number of 0.44. • The electron-rich species of imide group is able to uniformly disperse the flux of lithium ion. [ABSTRACT FROM AUTHOR]