Negative electrode
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Solution Overview
Problem
Conventional lithium secondary batteries experience increased resistance when left at high temperatures for extended periods due to issues with negative electrode paste viscosity and composition, affecting productivity and performance.
Innovation Solution
Incorporating trace amounts of Ti, Si, or Cr into the negative electrode active material layer, within specific mass ppm ranges, to maintain appropriate viscosity and prevent resistance increase during high-temperature storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional negative electrode materials are used, then the battery can be manufactured with standard processes, but the resistance increases when the battery is stored at high temperature for a long period
Solution Approach 1:
The invention changes the chemical composition parameters of the negative electrode active material by incorporating specific elements (Li, Na, K, Ca, Sr, Ba, or Al) at controlled concentrations (0.1-5 mass%). This parameter modification prevents resistance increase during high-temperature storage while maintaining the material's fundamental graphite structure and electrochemical performance.
Solution Approach 2:
The invention creates a composite negative electrode active material by combining graphite with small amounts of specific elements (Li, Na, K, Ca, Sr, Ba, or Al). This composite structure leverages the high capacity of graphite while the added elements prevent resistance increase, achieving synergistic effects that improve overall battery reliability.
2Productivity
If the negative electrode paste viscosity is reduced for easier manufacturing, then productivity improves, but the paste may become too thin to form proper electrode structure
Solution Approach 1:
The invention modifies the paste viscosity by controlling the concentration of specific elements in the negative electrode active material. The optimized element content (0.1-5 mass%) adjusts the paste rheology to an ideal range, enabling smooth application and formation of uniform electrodes without being too thick or too thin, thus improving both manufacturing efficiency and quality.
3Reliability
If the content of trace components is increased to improve resistance stability, then high temperature performance improves, but the manufacturing complexity increases
Solution Approach 1:
The invention optimizes the concentration parameters of trace elements to a specific range (0.1-5 mass%) that provides sufficient resistance stability improvement without excessive complexity. This balanced parameter selection ensures effective performance enhancement while maintaining feasible manufacturing processes and cost-effectiveness.
Data Source
AI summary
Provided is a negative electrode in which during manufacture thereof a negative electrode paste has an appropriate viscosity, and which is capable of preventing an increase in resistance of a battery when left at a high temperature for a long period of time. A negative electrode disclosed herein includes a negative electrode current collector, and a negative electrode active material layer supported by the negative electrode current collector. The negative electrode active material layer contains a negative electrode active material, and a trace component. The trace component is at least one element selected from the group consisting of Ti, Si, Ca, and Cr. The content of the trace component is not less than 10 mass ppm and not more than 800 mass ppm with respect to the negative electrode active material.