Polyester Separator Hydrolysis Resistance via Moisture Adsorbent
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Solution Overview
Problem
Nonaqueous electrolyte batteries using polyester separators with active materials containing residual alkali components face increased battery resistance due to hydrolysis, leading to reduced cycle life performance.
Innovation Solution
Incorporating a positive electrode active material of LixNi1-a-bCoaMnbMcO2 with a separator having a pore volume of 0.9 to 3 cm3/g and an air permeability value of 2 to 15 sec/100 ml, made from polyester, and optionally combining with other polymers like cellulose or polyolefin, along with a moisture adsorbent like molecular sieve, to reduce hydrolysis and maintain battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyester separator is used, then the separator has high melting point and oxidation resistance, but the separator hydrolyzes in basic condition causing increased battery resistance
Solution Approach 1:
The patent introduces a moisture adsorbent as an intermediary substance that absorbs residual water in the battery system. This mediator prevents water from reaching and hydrolyzing the polyester separator, thereby protecting the separator's integrity while maintaining its high melting point and oxidation resistance properties
Solution Approach 2:
The patent extracts and removes the harmful element (water) from the battery system by incorporating a moisture adsorbent that selectively absorbs and traps residual water, preventing it from causing hydrolysis of the polyester separator
2Reliability
If a separator with appropriate pore volume is used, then hydrolysis is reduced, but the separator structure becomes more complex
Solution Approach 1:
The patent creates a composite separator structure by combining polyester fibers with a moisture adsorbent. This composite material integrates the high melting point and oxidation resistance of polyester with the water-absorbing capabilities of the moisture adsorbent, achieving hydrolysis resistance without excessive structural complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the charge-and-discharge cycle performance and reduces battery resistance, improving the overall life characteristics of the nonaqueous electrolyte battery.
Implementation Method 1
a separator and a nonaqueous electrolyte, wherein the positive electrode includes a positive electrode active material containing LixNi1-a-bCoaMnbM1cO2 (0
Implementation Method 2
a separator made of polyester hydrolyzes in a basic condition
Data Source
AI summary
According to one embodiment, there is provided a nonaqueous electrolyte battery including a positive electrode, a negative electrode, a nonaqueous electrolyte and a separator. The positive electrode includes a positive electrode active material containing LixNi1-a-bCoaMnbMcO2 (0.9<x≤1.25, 0<a≤0.4, 0≤b≤0.45, 0≤c≤0.1, and M represents at least one element selected from the group consisting of Mg, Al, Si, Ti, Zn, Zr, Ca, and Sn). The separator includes polyester. A pore volume in a pore size distribution according to a mercury intrusion porosimetry is in a range of 0.9 cm3/g to 3 cm3/g. An air permeability value according to a Gurley method is in a range of 2 sec/100 ml to 15 sec/100 ml.