The Influence of Multiple Stimulations on the Unusual Delamination Phenomenon of a Li-Ion Battery Separator Prepared by a Wet Process

Abstract

In this article, the unusual delamination phenomenon of LIB separators prepared by a wet process is reported. Meanwhile, a simple tearing test is proposed to quantify the delamination trend from the energy point of view and the effects of the tearing rate and temperature on the delamination trend of the separator were researched. Increasing the temperature makes separator delamination much more difficult, while the tearing rate has weaker effects on the separator delamination trend at lower temperatures but has a stronger influence at higher temperatures. In addition, the delamination trend of the separator in various electrolytes and under repeated compression cycles, which happened to the separator during battery cycles, is also investigated in detail. Also, the results show that the energy consumption per unit area during delamination decreases distinctly with increasing number of compression cycles, which was also influenced severely by different kinds of electrolytes with different Hildebrand interaction parameter.

Review of Multifunctional Separators: Stabilizing the Cathode and the Anode for Alkali (Li, Na, and K) Metal–Sulfur and Selenium Batteries

“…In a recent article, the repeated dynamic compression during charge−discharge cycling was observed to gradually induce a partial point electrolyte shortage for an undisclosed commercial separator. 527 In the study, the degraded performance was associated with a substantial reduction in electrolyte retention within the separator. While the study focused primarily on a tearing response under a single cycle (monotonic loading), there was no mention of a tearing or cracking response related to the cyclic loading.…”

“…There have been very few published studies on the cyclic response of even the most common polyolefin separators for existing lithium ion batteries. In a recent article, the repeated dynamic compression during charge–discharge cycling was observed to gradually induce a partial point electrolyte shortage for an undisclosed commercial separator . In the study, the degraded performance was associated with a substantial reduction in electrolyte retention within the separator.…”

The unusual delamination phenomenon of three kinds of lithium‐ion battery separators

“…However, this did not mean that there was no possibility of further development of LIB separator microstructure. An unusual delamination phenomenon of separators prepared by the wet process was reported first in our previous work 40 . We proposed that the connection or support structure along the normal thickness direction affects the delamination trend of the separator considerably.…”

“…Then the cast film is subjected to biaxial stretching with a high draw ratio (about 6.6 or more in industry), which is much higher than the dry process with biaxial stretching (about 3.3). During biaxial stretching, the bi‐continuous structure is stretched in‐plane, which can significantly reduce the connection or support structure per unit area 40 . After stretching, the paraffin oil is extracted to obtain the final microporous membrane, while the poor connections along the thickness direction of the structure are retained, which should account for the strong delamination tendency.…”

In situ visualizing the interplay between the separator and potassium dendrite growth by synchrotron X-ray tomography

“…37 One may attribute the difference to the high Young's modulus of Li whiskers, up to 130 MPa, that greatly exceeds the Young's modulus of the separator. 38,39 In addition, the shear modulus of potassium metal (1.3 GPa) is also lower than that of lithium metal (4.1 GPa), which is potentially another explanation. 5,,40 The lamination of Celgard 2325 separator indicates that the weak interaction force among the PP/PE/PP layers could not sustain the dramatic volume change of K-nearly 4 times larger than that of Li-during potassium plating/stripping process.…”