Dual-Active Material Positive Electrode for Wide SOC Range
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Solution Overview
Problem
Non-aqueous electrolyte solution secondary batteries with two types of positive electrode active materials having different average discharge potentials face significant decreases in output at low State Of Charge (SOC) due to uneven reactivity, leading to reduced cycle durability.
Innovation Solution
A method of manufacturing these batteries involves forming a positive electrode composite layer with a first positive electrode active material having a lower average discharge potential and a second active material with a higher potential, where the conductive materials' oil absorption numbers are balanced to control reactivity, ensuring the first active material reacts preferentially at low SOC and the second at intermediate SOC, maintaining high output across a wide SOC range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two types of positive electrode active materials having different average discharge potentials are mixed to expand the potential range for high output, then the SOC range for high output is expanded, but cycle durability deteriorates due to uneven reactivity and preferential reaction of one material
Solution Approach 1:
The patent applies local quality by controlling the spatial distribution and concentration of different positive electrode active materials within the composite layer. By carefully selecting the mass ratios and arranging materials with different discharge potentials in specific proportions, the patent creates localized regions with optimized reactivity characteristics, preventing uniform preferential reaction throughout the electrode and thereby improving cycle durability while maintaining wide SOC range adaptability.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the mass ratios of different positive electrode active materials (first and second active materials) within specific ranges. By changing these compositional parameters and controlling the average discharge potential differences, the patent optimizes the balance between expanding the high-output SOC range and maintaining cycle durability, resolving the contradiction through precise parameter control.
2Power
If the first positive electrode active material with lower average discharge potential is used to maintain high output at low SOC, then output at low SOC is improved, but the material reacts preferentially and deteriorates faster, reducing cycle durability
Solution Approach 1:
The patent applies partial or excessive action by intentionally allowing the first positive electrode active material (with lower discharge potential) to react preferentially to some extent during charging/discharging cycles. This preferential reaction is controlled within specific mass ratio boundaries (10-50 mass%) to ensure sufficient output at low SOC while preventing complete exhaustion or excessive deterioration of this material, thereby balancing power delivery with cycle durability.
Solution Approach 2:
The patent employs composite materials by creating a positive electrode composite layer that integrates two different positive electrode active materials with distinct discharge potentials. This composite structure allows the first material to provide high output at low SOC through preferential reaction, while the second material serves as a buffer and backup, ensuring overall electrode stability and extended cycle life through synergistic interaction.
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 approach maintains high output in a wide SOC range and enhances cycle durability by balancing the reactivity of the two positive electrode active materials, preventing excessive conductive material usage and ensuring efficient electrolyte interaction.
Implementation Method 1
The first conductive material has a first oil absorption number with respect to 100 parts by mass of the first positive electrode active material. The second conductive material has a second oil absorption number with respect to 100 parts by mass of the second positive electrode active material.
Data Source
AI summary
A method of manufacturing a non-aqueous electrolyte solution secondary battery includes: (A) preparing a first composite material by mixing a first positive electrode active material, a first conductive material and a first binder; (B) preparing a second composite material by mixing a second positive electrode active material, a second conductive material and a second binder; and (C) manufacturing a positive electrode by forming a positive electrode composite layer including the first composite material and the second composite material. The first positive electrode active material has an average discharge potential lower than that of the second positive electrode active material. The first conductive material has a first OAN. The second conductive material has a second OAN. A ratio of the second OAN to the first OAN is 1.3 or more and 2.1 or less. A sum of the first OAN and the second OAN is 31.64 ml/100 g or less.