Simultaneously Blocking Chemical Crosstalk and Internal Short Circuit via Gel‐Stretching Derived Nanoporous Non‐Shrinkage Separator for Safe Lithium‐Ion Batteries

Abstract

The separator, an ionic permeable and electronic insulating membrane between cathode and anode, plays a crucial role in the electrochemical and safety performance of batteries. However, commercial polyolefin separators not only suffer from inevitable thermal shrinkage at elevated temperature, but also fail to inhibit the hidden chemical crosstalk of reactive gases such as O2, leading to often reported thermal runaway (TR) and hence preventing large‐scale implementation of high‐energy‐density lithium‐ion batteries. Herein, a nanoporous non‐shrinkage separator (GS‐PI) is fabricated via a novel gel‐stretching orientation approach to eliminate TR. In situ synchrotron small angle X‐ray scattering during heating clearly shows that the as‐prepared thin GS‐PI separator exhibits superior mechanical tolerance at high temperature, thus effectively preventing internal short circuit. Meanwhile, the unique nanoporous structure design further blocks chemical crosstalk and the associated exothermic reactions. Accelerating rate calorimetry tests reveal that the practical 1 Ah LiNi0.6Co0.2Mn0.2O2 (NCM622)/graphite pouch cell using GS‐PI nanoporous separator show a maximum temperature rise (dT/dtmax) of only 3.7 °C s−1 compared to 131.6 °C s−1 in the case of Al2O3@PE macroporous separator. Moreover, despite the reduced pore size, the GS‐PI separator demonstrates better cycling stability than conventional Al2O3@PE separator at high temperature without sacrificing specific capacity and rate capability.

Thermal-Switchable, Trifunctional Ceramic–Hydrogel Nanocomposites Enable Full-Lifecycle Security in Practical Battery Systems

“…The application of natural convection or forced cooling around the cells and the coating of cells with phase change materials (PCMs) , can effectively avoid heat accumulation in fast charging–discharging mode. Many strategies, such as nonshrinkage separators, nonflammable electrolytes or additives, , the “self-poisoned” technique, and positive temperature coefficient (PTC)-modified current collectors, have been applied to avoid TR at the cell level. However, it should be noted that failure events at the system level are even more unpredictable, complicated, and destructive than those present at the cell level.…”

All-Fluorinated Electrolyte Enables Safe LiNi0.8Co0.1Mn0.1O2|Graphite Pouch Cells with Stable High-Voltage Operation

“…In addition, the anode reacts with the electrolyte to generate hydrogen during heating. The crosstalk between oxygen and hydrogen in the battery is the main cause of TR . Therefore, it is very meaningful to explore the thermal and gas conditions of the cathode and anode based on different electrolytes.…”

Challenges and Opportunities to Mitigate the Catastrophic Thermal Runaway of High‐Energy Batteries

“…Reproduced with permission. [300] Copyright 2022, Wiley-VCH. i) DSC profiles of graphite with Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 (LLZNO), lithium metal with LLZNO, LCO|LLZNO|AG, and LCO|LLZNO|Li (LCO, LiCoO 2 ; AG, artificial graphite).…”

“…a) Illustration of exothermic reactions inside the battery with or without chemical crosstalk blocking separator at elevated temperatures. Reproduced with permission [300]. Copyright 2022, Wiley-VCH.…”