A Separator with a Novel Thermal Crosslinking Structure Based on Electrospun PI/A‐POSS for Lithium‐Ion Battery with High Safety and Outstanding Electrochemical Performance

Abstract

In this study, a polyimide/aminopropyllsobutyl polyhedral oligomeric silsesquioxane (PI/A‐POSS) membrane with a novel 3D thermal crosslinking structure is prepared by electrospinning and subsequent imidization. Compared with the pure PI membrane, PI/A‐POSS composite membranes present better mechanical properties, narrower distribution of pore size, smaller average pore size, and better thermal stability. When A‐POSS content is 3 wt%, the composite membrane (A3) has outstanding electrolyte uptake, excellent ionic conductivity, low interfacial resistance, and the high electrochemical stability of anode. The battery assembled with the A3 separator has an excellent first discharge capacity of 137.8 mAh g−1 and its capacity retention rate is still as high as 76.49% after 100 cycles at 2.0 C. Furthermore, battery assembled with the A3 separator shows excellent rate capacity with a relatively high discharge capacity up to 169.7 mAh g−1 at 0.2 C and a superior capacity recovery rate of 98.06% at 30 °C. Especially, the battery assembled with the A3 separator shows more prominent rate capacity with an excellent first discharge capacity up to 180.5 mAh g−1 at 0.2 C and a superior capacity recovery rate of 95.79% at 60 °C.

Yolk–Shell Structured ST@Al2O3 Enables Functional PE Separator with Enhanced Lewis Acid Sites for High‐Performance Lithium Metal Batteries

“…These results demonstrate that the inorganic coating can significantly improve the mechanical properties of the separator, and the modified ST@Al 2 O 3 ‐PE membrane exhibited the most excellent tensile properties. [ 28 ]…”

“…The mechanical strength of a battery separator plays a critical role in ensuring its safety. In order to prevent potential safety risks stemming from separator failure, lithium-ion battery separators must possess a certain level of It clearly shows that the coated and modified PE separators exhibit significantly improved tensile strength and elongation at break compared to plain PE, [7,28] Specifically, the tensile strength of Al 2 O 3 -PE separator (143.2 MPa), S@Al 2 O 3 -PE separator (144.14 MPa), and ST@Al 2 O 3 -PE separator (148.94 MPa) was 28.4% and 32.6% higher, respectively, than that of the PE separator (112.27 MPa). Moreover, the elongation at break of the PE separator (48.64%) was observed to be lower compared to Al 2 O 3 -PE (51.16%), S@Al 2 O 3 -PE (53.21%), and ST@Al 2 O 3 -PE (53.28%) separators.…”

“…These results demonstrate that the inorganic coating can significantly improve the mechanical properties of the separator, and the modified ST@Al 2 O 3 -PE membrane exhibited the most excellent tensile properties. [28] High ionic conductivity can effectively reduce the polarization inside the battery, which is conducive to the stable stripping and deposition of lithium metal anodes and the fast charging and discharging capability of the battery. [10] From the Nyquist plot, the intrinsic impedances of S@Al 2 O 3 -PE and ST@Al 2 O 3 -PE are 1.68 Ω and 1.51 Ω, and the ionic conductivity is calculated to be 4.99 and 5.55 mS cm −1 , respectively, which are greater than that of the PE separator (3.00 mS cm −1 ) and 300-PE separator (3.69 mS cm −1 ) (Figure 4a).…”

“…Figure 4. a) Nyquist plots of the batteries applying PE, 300-PE, S@Al 2 O 3 -PE, and ST@Al 2 O 3 -PE separators, respectively; b) LSV test pattern of different separators; c,d) lithium-ion transference numbers of PE and ST@Al 2 O 3 -PE separators; e) lithium stripping/deposition performance of Li/Li symmetric cells assembled with different separators at a current density of 1 mA cm 2 mechanical strength. Figure 3i illustrates the stress-strain curves of PE, PE-Al 2 O 3 , S@Al 2 O 3 -PE, and ST@Al 2 O 3 -PE membranes.It clearly shows that the coated and modified PE separators exhibit significantly improved tensile strength and elongation at break compared to plain PE,[7,28] Specifically, the tensile strength of Al 2 O 3 -PE separator (143.2 MPa), S@Al 2 O 3 -PE separator (144.14 MPa), and ST@Al 2 O 3 -PE separator (148.94 MPa) was 28.4% and 32.6% higher, respectively, than that of the PE separator (112.27 MPa). Moreover, the elongation at break of the PE separator (48.64%) was observed to be lower compared to Al 2 O 3 -PE (51.16%), S@Al 2 O 3 -PE (53.21%), and ST@Al 2 O 3 -PE (53.28%) separators.…”

“…Moreover, the elongation at break of the PE separator (48.64%) was observed to be lower compared to Al 2 O 3 -PE (51.16%), S@Al 2 O 3 -PE (53.21%), and ST@Al 2 O 3 -PE (53.28%) separators. These results demonstrate that the inorganic coating can significantly improve the mechanical properties of the separator, and the modified ST@Al 2 O 3 -PE membrane exhibited the most excellent tensile properties [28]. High ionic conductivity can effectively reduce the polarization inside the battery, which is conducive to the stable stripping and deposition of lithium metal anodes and the fast charging and discharging capability of the battery [10].…”