Low-Cost and Large-Scale Fabricating Technology for High-Performance Lithium-Ion Battery Composite Separators with Connected Nano-Al₂O₃ Coating

Abstract

The ever-increasing demand for high power density improves lithium-ion batteries. However, the poor microporous structure and inferior compatibility of separators heighten the lithium-ion migration barrier. Based on the cavitation of β-crystal polypropylene (β-iPP), separators with connected nano-Al2O3 coating are prepared by facile extrusion and biaxial stretching processes of β-iPP and nano-Al2O3. The crystal structure and microporous morphology diagnoses indicate that the moderate nano-Al2O3 content refines coarse fibrils and homogenizes pore size dispersion of the separator after biaxial stretching. Also, the connected nano-Al2O3 coating remains on the surface and inner pore wall because pores arise directly at nano-Al2O3/β-iPP interfaces, which endows the separator with superior electrolyte affinity. Assembled batteries further exhibit better C-rate capacity and cycle stability owing to the stable solid electrolyte interface formation and a higher lithium-ion transference number. Especially, the compound separator possesses the highest Li+ transference number of 0.53 and discharge capacity retention of 88.7% after 100 cycles as the nano-Al2O3 content is increased to 6%. This facile fabrication technique ameliorates the porous structure and electrochemical properties of the separator simultaneously, which provides practical guidance for the high-performance separator manufacturing technology in a large scale with low cost.

Metal‐Organic Framework Sandwiching Porous Super‐Engineering Polymeric Membranes as Anionphilic Separators for Dendrite‐free Lithium Metal Batteries

“…a) Nyquist plots of symmetrical SS||SS cells and b) EIS results of symmetrical Li||Li cells with PP, PEN, PEN@PDA, and MOFs/NA/MOFs separators; c) Comparison of ionic conductivity of various separators; Comparison of linear sweep voltammetry (LSV) curves of the d) PP, e) PEN, and f) MOFs/NA/MOFs separators;g) Comparison of ionic conductivity and t Li + of the reported separators and separators in this work; [ 9,12,29 ] h) Raman signals of free EC and AWL in electrolytes. i) Raman signals of Li + ‐EC and free EC in electrolytes.…”

Novel preparation of lithium‐ion battery wet‐processed separator based on the synergistic effect of porous skeleton nano‐Al2O3in situ blending and synchro‐draw

“…Lower interface impedance generates excellent separator–electrode compatibility and improves ion diffusion through the separator–electrode interface. Also, higher ionic conductivity and Li + transport number accelerate Li + transport within the separator and depress contra‐ion polarization 37,46 . All the above‐mentioned conditions contribute to an optimized discharge capacity of cells packaged with PE‐S‐Al.…”

Low-Cost Mass Manufacturing Technique for the Shutdown-Functionalized Lithium-Ion Battery Separator Based on Al2O3 Coating Online Construction during the β-iPP Cavitation Process

“…PP, Al 2 O 3 , and PE were mixed with masterbatch again to obtain three cast films, namely, PP (pure β-iPP), PP-Al 2 O 3 (95 wt % β-PP + 5 wt % Al 2 O 3 ), and PP–Al 2 O 3 –PE (70 wt % β-PP + 5 wt % Al 2 O 3 + 25 wt % PE). Our previous study , suggested that 5 wt % nano-Al 2 O 3 has the best optimization effect on the microporous structure. Excessive nano-Al 2 O 3 (>5 wt %) agglomerates severely within β-iPP and worsens the pore size dispersion in reverse.…”

“…Blending hydrophilic nano-Al 2 O 3 into β-iPP cast film imports affluent infirm interfaces between two phases. In the circumstances, the crude fibrils originating from contracted β-lamellae during longitudinal draw can be refined during transverse drawing because of the presence of nano-Al 2 O 3 /β-iPP infirm boundaries in 40,41 suggested that 5 wt % nano-Al 2 O 3 has the best optimization effect on the microporous structure. Excessive nano-Al 2 O 3 (>5 wt %) agglomerates severely within β-iPP and worsens the pore size dispersion in reverse.…”