Polymeric Layer Battery Separator for Heat Resistance
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Solution Overview
Problem
Non-aqueous secondary batteries face challenges in achieving high heat resistance, resistance to liquid leakage, and maintaining cycle characteristics due to issues with electrolyte solution distribution and separator materials, leading to potential internal short circuits and thermorunaway.
Innovation Solution
A non-aqueous electrolyte secondary battery design featuring a separator with 90% polyethylene by mass and a polymeric layer holding 13-25% electrolyte salt, along with a polymeric support layer that adheres to the electrodes, ensuring efficient electrolyte distribution and preventing excessive heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of electrolytic solution is increased to improve cycle characteristic, then cycle characteristic is improved, but the battery size and weight increase
Solution Approach 1:
The patent uses a flexible polymeric film as the separator instead of traditional porous structures. This film can be swollen with electrolyte to provide both mechanical separation and electrolyte reservoir functions, reducing the need for excessive electrolyte volume while maintaining cycle performance.
Solution Approach 2:
The electrolyte is nested within the polymeric film structure itself through swelling, creating a hierarchical structure where the film contains the electrolyte. This eliminates the need for separate electrolyte compartments and reduces overall battery volume and weight.
2Use of energy by moving object
If the separator thickness is reduced to improve energy density, then energy density is improved, but heat resistance and safety deteriorate
Solution Approach 1:
The patent employs a composite structure consisting of a polymeric base film combined with inorganic heat-resistant particles. This composite provides both the thin profile needed for high energy density and the thermal stability required for safety, as the inorganic particles maintain structural integrity at elevated temperatures.
Solution Approach 2:
The patent changes the material parameters of the separator by using polymers with high glass transition temperatures and incorporating heat-resistant fillers. This allows the separator to maintain its mechanical properties and shutdown function at higher temperatures despite reduced thickness.
3Reliability
If polyethylene is used for separator to achieve shutdown function, then shutdown function is improved, but heat resistance deteriorates due to heat shrinkage at high temperature
Solution Approach 1:
The patent creates a composite separator where polyethylene provides the shutdown function through its low melting point, while inorganic heat-resistant particles and high-temperature polymer matrices prevent heat shrinkage. The composite structure allows the polyethylene to perform its shutdown function without suffering from the heat shrinkage problem of pure polyethylene.
Solution Approach 2:
The patent introduces heat-resistant inorganic particles and high-temperature polymer matrices as intermediary materials that mediate between the polyethylene's shutdown function and the requirement for heat resistance. These intermediaries provide structural support at high temperatures while allowing the polyethylene component to perform its thermal shutdown function.
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 battery achieves excellent heat resistance, resistance to liquid leakage, and improved cycle characteristics while maintaining high energy density, as demonstrated by a maximum temperature not exceeding 100°C during safety tests and effective capacity retention.
Implementation Method 1
The polymeric layer holds therein a non-aqueous electrolytic solution
Implementation Method 2
when the temperature of the battery increases due to some factor, pores of the separator are clogged, and a battery reaction is stopped by inhibiting the movement of an ion
Implementation Method 3
at an abnormal time such as short circuit and overcharge, the possibility of more excessive generation of heat generation than before is large
Data Source
AI summary
A battery is provided. The battery includes a positive electrode; a negative electrode; a separator between the positive and negative electrodes; a polymeric layer between the separator and one or both of the positive electrode and the negative electrode, the polymeric layer including an electrolytic solution comprising 13% by mass to 25% by mass of an electrolyte salt; and an exterior member housing the positive electrode, the negative electrode, the separator, and the polymeric layer, wherein the battery has a maximum attained temperature not higher than 100° C. based on a nail piercing safety test.