Lithium Iron Phosphate Electrode with Conductive Carbon Coating
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Solution Overview
Problem
Conventional positive electrodes for non-aqueous electrolyte secondary batteries face challenges in achieving high-rate cycling performance and maintaining performance at low temperatures, particularly due to high electrical resistance and inefficient lithium ion conduction.
Innovation Solution
A positive electrode design featuring a conductive carbon-coated lithium iron phosphate active material layer with specific pore structures and carbon content, optimized to enhance lithium ion conduction and reduce non-conductive material proportion, thereby improving cycling performance and low-temperature discharge capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium iron phosphate is used as the positive electrode active material, then the battery capacity is improved, but the electrical resistance increases
Solution Approach 1:
The patent applies local quality by coating only the surface of the lithium iron phosphate particles with carbon, rather than making the entire particle conductive. This creates a localized conductive layer that reduces electrical resistance at the particle surface while maintaining the high capacity characteristics of the bulk lithium iron phosphate material.
Solution Approach 2:
The patent uses composite materials by combining lithium iron phosphate with a carbon coating layer. This composite structure integrates the high capacity advantage of lithium iron phosphate with the high electrical conductivity advantage of carbon, resolving the contradiction between capacity and resistance.
2Productivity
If the proportion of non-conductive material in the positive electrode is reduced, then the high-rate cycling performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the carbon content within the specific range of 3-15 mass%. This optimized parameter balance ensures sufficient conductivity for high-rate performance while avoiding excessive carbon that would require more complex manufacturing processes to achieve uniform distribution.
Solution Approach 2:
The patent applies preliminary action by pre-coating the lithium iron phosphate particles with carbon before electrode assembly. This preliminary surface treatment ensures that the active material particles are ready for high-rate cycling from the start, eliminating the need for complex post-assembly conductivity modifications.
3Reliability
If the carbon coating content is increased, then the electrical resistance is reduced, but the proportion of non-conductive material increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the carbon content parameter to a specific range (3-15 mass%). This precise parameter control ensures that enough carbon is present to reduce electrical resistance effectively, while preventing excessive carbon accumulation that would create non-conductive regions and harm high-rate cycling performance.
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 proposed electrode configuration significantly enhances high-rate cycling performance and low-temperature discharge capabilities by optimizing the carbon coating and pore structure, leading to improved battery efficiency and stability.
Implementation Method 1
a coated section comprising a conductive carbon... the positive electrode active material layer has a conductive carbon content of 0.5 to 3.0 % by mass... to enhance lithium ion conduction and reduce non-conductive material proportion
Implementation Method 2
the positive electrode active material layer has a pore specific surface area of 5.0 to 10.0 m2... to enhance lithium ion conduction
Data Source
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AI summary
The present relates to a positive electrode (1) for a non-aqueous electrolyte secondary battery, comprising: a positive electrode current collector (11) comprising a positive electrode current collector main body (14) formed of a metal material; a positive electrode active material layer (12) provided on the positive electrode current collector (11), wherein the positive electrode active material layer (12) comprises a positive electrode active material having, on at least a part of its surface, a coated section comprising a conductive material, the positive electrode active material layer (12) has a pore specific surface area of 5.0 to 10.0 m2/g and a central pore diameter of 0.06 to 0.15 μm, and a positive electrode (1) for a non-aqueous electrolyte secondary battery, comprising a positive electrode current collector (11) and a positive electrode active material layer (12) provided on the positive electrode current collector (11), wherein a thickness of the positive electrode active material layer (12) is 10 μm or more, the positive electrode active material layer (12) comprises a positive electrode active material, and a reflectance of a surface of the positive electrode active material layer (12) is 5.5 % or higher in a wavelength range of 200 nm to 850 nm, and is not higher than a reflectance in the wavelength range of 200 nm to 850 nm peculiar to the positive electrode active material contained in the positive electrode active material layer (12).