Positive Electrode Carbon Distribution for Low-Temperature Battery Output
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in maintaining output performance in extremely low-temperature environments and after repeated charge-discharge cycles.
Innovation Solution
Incorporating an appropriate amount of conductive carbon into the positive electrode active material layer to reduce resistance differences between particles, forming an excellent conductive path, with specific ratios of carbon to iron atom intensities and optimized carbon distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional positive electrode composition is used, then basic battery function is achieved, but output performance in extremely low-temperature environments deteriorates
Solution Approach 1:
The patent applies local quality by creating a carbon-rich environment specifically at the particle surfaces and interfaces within the positive electrode active material layer. Scanning Auger electron spectroscopy reveals that carbon atoms are concentrated at specific locations (indicated by higher Cmax/Femax ratios), forming localized conductive paths where needed most for low-temperature performance, rather than uniformly distributing carbon throughout the entire electrode.
Solution Approach 2:
The patent utilizes parameter changes by optimizing the Cmax/Femax ratio (a specific parameter derived from Auger electron spectroscopy measurements) to fall within 10.0-35.0, and the C90/C10 ratio to fall within 1.0-2.5. These parameter optimizations reflect controlled changes in carbon distribution characteristics, transforming the electrode's electrical conductivity properties to maintain performance across extreme temperature ranges.
2Duration of action of stationary object
If conventional positive electrode composition is used, then initial capacity is achieved, but cycle performance deteriorates after repeated charge-discharge cycles
Solution Approach 1:
The patent applies preliminary action by pre-establishing a carbon distribution structure with optimized Cmax/Femax and C90/C10 ratios before the battery undergoes charge-discharge cycling. This pre-configured conductive network anticipates the degradation that occurs during cycling and maintains electrical connectivity throughout the active material particles, ensuring stable output performance is preserved after repeated cycles.
3Power
If carbon content is increased to improve conductivity, then low-temperature output performance improves, but manufacturing precision becomes difficult to control
Solution Approach 1:
The patent replaces direct mechanical control of carbon content with a spectroscopic measurement-based approach. Instead of relying on precise mechanical mixing and weighing to achieve uniform carbon distribution, the invention uses scanning Auger electron spectroscopy to measure and characterize carbon atom intensity (Cmax and Femax values), substituting physical measurement and characterization for mechanical process control.
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
Improves output performance in low-temperature environments and maintains performance after charge/discharge cycles, enhancing cycle performance and low-temperature stability.
Implementation Method 1
By allowing an appropriate amount of conductive carbon to be present in the positive electrode active material layer in an appropriate state to reduce the resistance difference between the positive electrode active material particles, excellent conductive path can be formed.
Data Source
AI summary
A positive electrode for a non-aqueous electrolyte secondary battery, including a positive electrode current collector and a positive electrode active material layer including one or more positive electrode active material particles provided on one or both surfaces of the positive electrode current collector. The positive electrode active material layer includes carbon atoms and iron atoms, and Cmax/Femax is 10.0 or more and 35.0 or less, which is a ratio of the most frequent carbon atom intensity Cmax to the most frequent iron atom intensity Femax, wherein the Cmax and the Femax are obtained from histograms of carbon atom intensity and iron atom intensity, each determined by performing scanning Auger electron spectroscopy with respect to a total of 65,536 measurement points formed by vertically aligned 256 points×horizontally aligned 256 points within an area of 100 μm×100 μm on a surface of the positive electrode active material layer.