Non-aqueous electrolyte battery with mixed graphite anode
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Solution Overview
Problem
Lithium-ion secondary batteries with high volume density electrodes suffer deformation during charge and discharge cycles, leading to capacity deterioration when using a laminate film casing, which lacks the rigidity to prevent pressure changes and electrode separation.
Innovation Solution
A non-aqueous electrolyte battery design featuring a negative electrode with an anode mixture layer of 1.70 to 1.90 g/cm3 density, composed of mixed particles of spherical and non-spherical graphite, and a polymer compound layer on the separator to enhance adhesion and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the volume density of the electrode mixture is increased to achieve high energy density, then the battery capacity and energy density are improved, but the electrode undergoes marked deformation during charge and discharge cycles
Solution Approach 1:
The patent optimizes the volume density parameter of the negative electrode to a specific range (1.65 to 1.85 g/cm³) and controls the particle size distribution of graphite (D10: 3-8 μm, D50: 12-25 μm, D90: 20-45 μm) to achieve high energy density while minimizing electrode deformation during cycling
Solution Approach 2:
The patent uses a composite structure consisting of the negative electrode, separator, and polymer compound layer together, where the polymer layer complements the laminate film casing to provide additional mechanical support and prevent electrode deformation without compromising the high volume density
2Weight of moving object
If a laminate film is used as a casing member to reduce battery size and weight, then the battery dimensions and weight are reduced, but the rigidity is insufficient to prevent battery deformation
Solution Approach 1:
The patent employs a laminate film as the battery casing to achieve reduced weight and dimensions, while compensating for the insufficient rigidity by introducing a polymer compound layer between the electrode and separator that provides additional mechanical support during charge and discharge cycles
Solution Approach 2:
The patent introduces a polymer compound layer as an intermediary element between the negative electrode and separator, which acts as a mechanical buffer to prevent electrode deformation and maintain contact pressure, thereby compensating for the low rigidity of the laminate film casing
3Quantity of substance
If the electrode deforms during charge and discharge cycles, then the battery achieves high initial capacity, but the gap between electrode and separator widens causing capacity deterioration
Solution Approach 1:
The patent performs preliminary optimization of the negative electrode volume density (1.65 to 1.85 g/cm³) and particle size distribution before assembly, ensuring that the electrode maintains stable dimensions during cycling, which prevents gap formation between the electrode and separator and maintains capacity over extended cycle life
Data Source
AI summary
A non-aqueous electrolyte battery is disclosed. The non-aqueous electrolyte battery include a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The negative electrode includes an anode mixture layer having a volume density of 1.70 to 1.90 g/cm3 prior to being subjected to charge and discharge processes. The anode mixture layer includes mixed particles composed of spherical graphite having an average particle size of 25 to 35 μm and non-spherical graphite having an average particle size of 8 to 22 μm.