Nonaqueous Battery Filler Layer Thickness and Pressure Control
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face issues with leakage current generation due to heat shrinkage of the separator sheet, leading to potential short circuits when used in retained states under high temperatures, as existing filler layers do not adequately prevent electrode active material penetration.
Innovation Solution
A nonaqueous electrolyte secondary battery design featuring a porous filler layer with an inorganic material and binder between the separator and electrodes, where the filler layer's average thickness is greater than the electrode active material's average particle diameter, and a pressure of at least 0.1 MPa is applied to maintain a constant interval between electrodes, preventing short circuits and leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a porous filler layer is formed between the separator and electrode to prevent short circuiting, then heat-resistant performance is improved, but leakage current generation occurs when separator melts at high temperatures
Solution Approach 1:
The invention changes the physical parameters of the filler layer by controlling particle size (0.1-10 μm) and thickness (5-20 μm) to optimize both heat resistance and leakage current prevention. The pressure application (0.1-10 MPa) further modifies the contact state between components to maintain performance at high temperatures
Solution Approach 2:
The invention uses composite structure combining separator sheet with porous filler layer containing inorganic particles and binder. This composite design provides both the heat resistance of inorganic materials and the functional properties of the separator, while preventing leakage current through proper structural configuration
2Power
If pressure is applied to the electrode assembly to maintain constant interval between electrodes, then battery output is improved, but electrode active material penetrates into the filler layer causing short circuits
Solution Approach 1:
The invention optimizes the pressure parameter within a specific range (0.1-10 MPa) to balance battery output and short circuit prevention. The filler layer thickness and particle size are also adjusted to withstand the applied pressure without allowing electrode material penetration
Solution Approach 2:
The porous filler layer acts as a cushioning barrier placed beforehand between the separator and electrode. This protective layer absorbs and distributes the applied pressure, preventing direct contact and potential short circuits between electrodes while maintaining electrical performance
3Reliability
If separator sheet is used to ensure ionic permeability, then ionic conductivity is improved, but separator undergoes heat shrinkage and shape change at high temperatures
Solution Approach 1:
The invention creates a composite structure where the separator sheet retains its ionic permeability function while the added porous filler layer with inorganic particles provides heat shrinkage resistance. The binder material in the filler layer maintains structural integrity at high temperatures
Solution Approach 2:
The porous filler layer acts as a flexible protective film on the separator surface. This thin film structure allows ionic permeability to pass through while providing mechanical stability and preventing heat-induced shape changes of the underlying separator
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 effectively suppresses leakage current generation and maintains battery output even at high temperatures by preventing electrode active material penetration into the filler layer, ensuring reliable operation and safety.
Implementation Method 1
A porous filler layer is formed between the separator and the positive electrode and/or the negative electrode. This filler layer contains a filler made of an inorganic material and contains a binder. The relationship T>D holds where T is an average thickness of the filler layer and D is an average particle diameter of an electrode active material present in the electrode facing the filler layer
Implementation Method 2
a pressure applied to the electrode assembly in the stacking direction is set to at least 0.1 MPa
Data Source
AI summary
A nonaqueous electrolyte secondary battery 100 according to the present invention is provided with an electrode assembly 80 having a structure in which a positive electrode 10 and a negative electrode 20 are stacked with a separator 30 interposed therebetween. A porous filler layer 32 is formed between the positive electrode 10 and the separator 30. The filler layer 32 contains a filler made of an inorganic material and contains a binder. The relationship T>D holds where T is the average thickness of the filler layer 32 and D is the average particle diameter of a positive electrode active material 15 present in the positive electrode 10 facing the filler layer 32, and a pressure applied to the electrode assembly 80 in the stacking direction is set to at least 0.1 MPa.