Lithium Nickel Composite Oxide Battery Separator Alkali Resistance
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Solution Overview
Problem
Lithium nickel composite oxide batteries face self-discharge failure due to alkaline substances eluting into the electrolyte, which compromises the alkali resistance of polyimide, polyamide, or polyamide imide separators, leading to reduced strength and increased risk of short circuits and accidents.
Innovation Solution
Incorporating an acid and/or acid anhydride into the electrolyte solution or a member in contact with it to neutralize alkaline components, thereby maintaining the separator's integrity and preventing self-discharge failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a separator made of polyimide, polyamide, or polyamide imide is used to achieve high heat resistance, then thermal stability is improved, but alkali resistance deteriorates due to elution of alkaline substances from lithium nickel composite oxide
Solution Approach 1:
A coating layer comprising fluorinated cyclic carbonate is introduced as an intermediary between the lithium nickel composite oxide positive electrode and the polyimide/polyamide separator. This coating layer acts as a protective barrier that prevents direct contact between alkaline substances eluting from the positive electrode and the separator, thereby maintaining the separator's alkali resistance while preserving its heat resistance properties.
Solution Approach 2:
The invention changes the chemical composition parameter of the electrolyte solution by adding fluorinated cyclic carbonate, which has specific chemical properties that suppress the elution of alkaline substances from the lithium nickel composite oxide. This parameter change reduces the alkalinity in the electrolyte solution, thereby protecting the separator from alkali-induced degradation while maintaining its thermal stability.
2Quantity of substance
If lithium nickel composite oxide with high Ni content is used to increase capacity and energy density, then energy density is improved, but self-discharge failure increases due to alkaline substance elution
Solution Approach 1:
The fluorinated cyclic carbonate coating layer serves as an intermediary protective barrier between the high-Ni lithium nickel composite oxide and the electrolyte solution/separator. This coating suppresses the elution of alkaline substances from the positive electrode into the electrolyte, preventing the chemical degradation that leads to self-discharge failure, while allowing the high-capacity material to function at full potential.
Solution Approach 2:
The addition of fluorinated cyclic carbonate to the electrolyte solution changes the chemical environment parameters, creating a more stable interface with the lithium nickel composite oxide. This parameter change reduces the chemical reactivity between the high-Ni cathode material and the electrolyte, suppressing alkaline elution and thereby reducing self-discharge failure rates.
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
The addition of acids or acid anhydrides effectively reduces the alkalinity of the electrolyte, preventing separator deterioration and significantly lowering the self-discharge failure rate in lithium ion secondary batteries with lithium nickel composite oxide positive electrodes.
Implementation Method 1
the battery includes an acid and/or an acid anhydride in an electrolyte solution and/or a member in contact with the electrolyte solution
Data Source
AI summary
Lithium ion secondary batteries are disclosed that include a positive electrode comprising a lithium nickel composite oxide as a positive electrode active material and a separator consisting of one or more layers selected from polyimide layer, polyamide layer, the battery having a low self-discharge failure rate even after long term storage. The lithium ion secondary batteries can include a positive electrode comprising a lithium nickel composite oxide and a separator consisting of one or more layers selected from polyimide layer, polyamide layer, and polyamide imide layer, wherein the battery comprises an acid and/or an acid anhydride in an electrolyte solution and/or a member in contact with the electrolyte solution.