Positive Electrode Carbon Coating for High-Temperature Rate Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for non-aqueous electrolyte secondary batteries do not adequately address the deterioration of battery performance during high-rate cycling at high temperatures, and the optimal amount and state of conductive carbon in the positive electrode are not specified.
Innovation Solution
The positive electrode for non-aqueous electrolyte secondary batteries is designed with a specific range of conductive carbon content (0.5 to 3.5% by mass) and amorphous carbon coating on the surface of the active material, optimizing the crystal condition to enhance high-rate cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively large amount of carbon (5 parts by mass relative to 90 parts by mass of positive electrode active material) is compounded into the positive electrode material, then the conducting agent content is increased to improve electrical conductivity, but many independent carbon particles are present in the electrode mixture layer which may increase impedance and reduce battery performance during high-rate cycling at high temperatures
Solution Approach 1:
The patent applies local quality by coating the surface of positive electrode active material particles with conductive carbon to create a carbon layer specifically where it is needed (at the particle surface) rather than distributing carbon uniformly throughout the electrode. This localized carbon coating provides necessary conductivity at the active material interface while minimizing the total amount of carbon required, thereby reducing the number of independent carbon particles in the electrode mixture layer.
Solution Approach 2:
The patent uses composite materials by creating a core-shell structure where the core is the positive electrode active material particle and the shell is a conductive carbon coating. This composite structure combines the electrochemical activity of the active material with the electrical conductivity of the carbon coating, achieving both functions in a integrated manner that reduces the need for additional independent carbon particles.
2Reliability
If the amount of conducting agent in the positive electrode is increased to improve electrical conductivity, then the electrical conductivity is enhanced, but the impedance increases and capacity retention deteriorates during high-rate cycling at high temperatures
Solution Approach 1:
The patent applies local quality by concentrating the conductive carbon specifically at the surface of active material particles where electron transfer occurs during charge/discharge cycles. This localized placement of conducting agent at the critical interface provides maximum conductivity benefit with minimum total carbon content, thereby reducing impedance without requiring large amounts of conducting agent that would otherwise be needed.
Solution Approach 2:
The patent changes the parameter of carbon distribution from uniform dispersion throughout the electrode to concentrated coating at particle surfaces. This parameter change in carbon placement strategy improves electrical conductivity at the active material interface while minimizing the overall carbon content and reducing the formation of independent carbon particles that increase impedance.
3Reliability
If carbon is coated on the surface of positive electrode active material particles to improve conductivity, then the electrical conductivity is enhanced, but the amount and state of conductive carbon is not optimally controlled leading to performance deterioration
Solution Approach 1:
The patent changes the parameter of carbon coating by specifying precise control of carbon content (0.5 to 3.5 mass%) and defining the carbon state as amorphous. This parameter optimization ensures sufficient conductivity enhancement while preventing excessive carbon deposition that would create independent carbon particles and increase impedance, thereby resolving the manufacturing precision issue.
Solution Approach 2:
The patent applies local quality by ensuring the carbon coating is specifically located on the surface of active material particles with controlled thickness and uniformity. This localized and controlled carbon coating provides consistent conductivity enhancement across all particles while maintaining precise control over the total carbon amount and its amorphous state, improving manufacturing precision.
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 design improves the battery's performance at high temperatures by maintaining impedance reduction and capacity retention during high-rate charge/discharge cycles.
Implementation Method 1
the surface of the positive electrode active material is coated with amorphous carbon as conductive carbon
Implementation Method 2
maintaining impedance reduction and capacity retention during high-rate charge/discharge cycles
Data Source
AI summary
A positive electrode for a non-aqueous electrolyte secondary battery, including: a positive electrode current collector having a positive electrode current collector main body formed of a metal material; and a positive electrode active material layer provided on the positive electrode current collector, wherein: the positive electrode active material layer includes a positive electrode active material and an conducting agent, or the positive electrode active material layer includes a positive electrode active material and does not include a conducting agent; one or both of the positive electrode current collector and the positive electrode active material layer includes conductive carbon; the conductive carbon includes amorphous carbon; and the conductive carbon is present in an amount of 0.5 to 3.5% by mass with respect to a mass of the positive electrode excluding the positive electrode current collector main body.