Progresses in Manufacturing Techniques of Lithium‐Ion Battery Separators in China

Abstract

The lithium‐ion batteries (LIBs) have been widely used in the world since the first introduction in 1991. The microporous polyolefin separator is the key component to determine the electrical properties and safety of LIBs. In China, the LIBs separators were completely imported and expensive before 2008. We have realized the industrialization of LIBs separators by either dry or wet process successfully. Nowadays, China has become the biggest manufacturing country of LIBs separators in the world and the price is very much reduced. Among the separator processing techniques, the dry process based on biaxial stretching β nucleated polypropylene (β‐iPP) was originated from China and has the lowest manufacturing cost. However, the separator produced by this method has non‐uniform pore size distribution which limits its wider application. In this article, based on the better understanding of original crystal morphology on the pore formation during stretching, we present our recent works to improve the performance of dry process separator through the preparation of β‐spherulites, casting technique optimization, improved annealing treatment and multi‐stages longitudinal stretching. As a result, we produced the dry process separator with much more uniform pore size distribution than that made from the traditional dry process.

Interfacial Degradation and Optimization of Li‐rich Cathode Materials†

“…Although the battery is comprised of electrode materials, separators, electrolyte, etc ., in terms of cost, the raw material in cathode accounts for 50% in state‐of‐the‐art LIBs. [ 1‐3 ] To date, substantial efforts from both the academic research and commercial application have focused on the design and optimization of cathode materials with a large capacity, high power/energy density, stable cyclability, low runtime cost, and favorable service security. Figure 1A illustrates the prospects and limitations of these conventional cathode materials.…”

Strategies of Removing Residual Lithium Compounds on the Surface of Ni‐Rich Cathode Materials†

“…[ 9‐12 ] However, the performance of LIBs, including energy density, safety, and service life, has not fully met various needs at the present stage, especially in the electric vehicles field. [ 13‐17 ] Therefore, the main development direction today is to produce LIBs with higher energy density, better safety, and lower cost. Cathode materials are an essential factor to make a breakthrough in this field.…”

High‐Voltage Layered Ternary Oxide Cathode Materials: Failure Mechanisms and Modification Methods†

“…Recent work has suggested an approach to improve the performance of dry process separator through the preparation of β‐spherulites, casting technique optimization, improved annealing treatment and multi‐stages longitudinal stretching, which could produce the dry process separator with much more uniform pore size distribution than that made from the traditional dry process. [ 65 ]…”