Lithium Iron Phosphate Cathode Mixture with Inorganic Oxide
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Solution Overview
Problem
Lithium iron phosphate batteries with an olivine type crystal structure face challenges in achieving sufficient output characteristics for high-power applications and maintaining life characteristics at high temperatures due to low electronic conductivity and binder segregation issues.
Innovation Solution
A cathode mixture is developed with a cathode active material having a particle diameter between 0.1 μm and 0.5 μm, incorporating an inorganic oxide that does not contribute to charge and discharge, where the particle diameter of the active material is larger than the inorganic oxide, improving the dispersing state of the conductive assistant and binder, thereby enhancing electronic conductivity and reducing binder swelling at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium iron phosphate with olivine type crystal structure is used as cathode active material, then cost is reduced and material supply security is improved, but electronic conductivity is lowered and charge/discharge capacitance is reduced
Solution Approach 1:
The patent applies parameter changes by controlling the particle diameter of lithium iron phosphate within a specific range (3.1 μm or less, preferably 1.0 μm or less) and adjusting the sintering temperature (900°C to 1100°C) to optimize the balance between electronic conductivity and material stability. This resolves the contradiction by finding optimal parameter values that maintain supply security while improving conductivity.
Solution Approach 2:
The patent creates a composite material structure by forming a cathode mixture containing lithium iron phosphate particles with controlled diameter, conductive assistants (carbon materials), and binders. This composite approach improves electronic conductivity through the conductive network while maintaining the cost and supply security benefits of lithium iron phosphate.
2Reliability
If particle diameter of cathode active material is reduced to increase specific surface area, then electronic conductivity is improved, but binder segregation occurs and life characteristics at high temperature deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle diameter of lithium iron phosphate within a specific range (3.1 μm or less) and optimizing the sintering conditions (temperature and time). This controlled parameter approach improves electronic conductivity while preventing excessive particle reduction that would cause binder segregation and high-temperature stability issues.
3Ease of manufacture
If conventional cathode mixture is used for high-power applications, then manufacturing is simplified, but output characteristics are insufficient and life characteristics at high temperature deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the particle diameter of lithium iron phosphate (3.1 μm or less) and sintering conditions (900°C to 1100°C for 0.5 to 48 hours). These parameter optimizations improve output characteristics and high-temperature life characteristics while maintaining a manufacturable process that does not require complex additional steps.
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 improves the electronic conductivity and life characteristics of the cathode, enabling better performance in high-power applications and maintaining stability at elevated temperatures.
Implementation Method 1
a cathode active material into/from which lithium can be doped and dedoped
Data Source
AI summary
A cathode mixture, a non-aqueous electrolyte secondary battery, and manufacture method thereof are provided. The cathode mixture for a non-aqueous electrolyte secondary battery includes: a cathode active material having an olivine type crystal structure; and an inorganic oxide which does not contribute to charge and discharge. A particle diameter A of the cathode active material lies within a range from 0.1 μm or more to 0.5 μm or less. There is a relation of A>B between the particle diameter A of the cathode active material and a particle diameter B of the inorganic oxide.