Battery Separator Material for High Voltage Stability
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Solution Overview
Problem
Lithium ion secondary batteries operating at charging voltages above 4.2 V experience intensified oxidation near the cathode, leading to separator degradation and increased risk of micro short circuits, particularly at high temperatures, which compromises cycle and high-temperature storage characteristics.
Innovation Solution
A battery design with an open circuit voltage range of 4.25 V to 6.00 V, utilizing a separator made of polyvinylidene fluoride, polytetrafluoroethylene, or aramid on the cathode side to enhance chemical stability and prevent micro short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the charging voltage is increased above 4.2 V to improve energy density, then the battery energy density is improved, but the separator is oxidized and decomposed leading to micro short circuits and reduced reliability
Solution Approach 1:
The patent changes the material composition parameter of the separator by incorporating inorganic particles (such as aluminum oxide, aluminum hydroxide, magnesium hydroxide, or titanium oxide) into the polyolefin matrix. This parameter change enables the separator to withstand higher charging voltages (above 4.2V) without oxidation and decomposition, thereby maintaining reliability while allowing higher energy density operation
Solution Approach 2:
The patent creates a composite separator structure by combining organic polyolefin material with inorganic particles. This composite material provides both the flexibility and porosity needed for ion transport and the thermal stability and oxidation resistance required to prevent micro short circuits at high charging voltages, thus resolving the contradiction between energy density and reliability
2Quantity of substance
If the charging voltage is increased above 4.2 V to improve energy density, then the battery energy density is improved, but the oxidation atmosphere near the cathode intensifies causing separator decomposition
Solution Approach 1:
The patent modifies the chemical composition parameters of the separator by adding inorganic particles with high oxidation resistance. These particles change the overall chemical stability parameter of the separator, enabling it to resist oxidation even in the intensified oxidation atmosphere created by charging voltages above 4.2V, thus maintaining separator integrity while achieving higher energy density
Solution Approach 2:
The inorganic particles act as sacrificial protective elements that can withstand oxidation without decomposing. By incorporating these stable inorganic components into the separator matrix, the patent creates a structure where the inorganic particles protect the organic polyolefin from oxidation, maintaining separator stability at high voltages while enabling improved energy density
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 design achieves improved energy density, cycle characteristics, and high-temperature storage performance by inhibiting micro short circuits and maintaining separator integrity even at elevated voltages.
Implementation Method 1
oxidation atmosphere particularly in the vicinity of the cathode surface is intensified. In the result, the separator physically contacting the cathode is oxidized and decomposed
Data Source
AI summary
A battery capable of improving the energy density and improving the battery characteristics such as cycle characteristics and high temperature storage characteristics. A cathode and an anode are oppositely arranged with a separator in between. The open circuit voltage in full charge is in the range from 4.25 V to 6.00 V. The separator has a base material layer and a surface layer. The surface layer opposed to the cathode is formed from at least one from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, polypropylene, and aramid.