Fibrous Carbon Additive Electrode for Secondary Battery
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Solution Overview
Problem
Conventional lithium-ion secondary batteries face challenges in achieving high electron conductivity and high capacity per electrode volume due to the insulating properties of binding agents and the need for increased conductive additives, which reduces the amount of active material and discharge capacity.
Innovation Solution
The use of a novel electrode structure incorporating fibrous carbon-containing compounds with a net-like structure and a lithium-containing composite oxide with an olivine crystal structure, where the fibrous carbon compounds form a conductive path and are in contact with the active material layer, enhancing electron conductivity while minimizing the amount of conductive additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ratio of binding agent to active material is increased to improve binding, then the electron conductivity is improved, but the amount of active material is relatively decreased, resulting in lower discharge capacity
Solution Approach 1:
The patent introduces conductive additives (acetylene black or graphite particles) as intermediary materials between the binding agent and active material. These conductive additives form a conductive network that compensates for the insulating effect of the binding agent, allowing higher binding agent ratios without sacrificing electron conductivity or discharge capacity.
2Reliability
If conductive additives are added to improve electron conductivity, then the electron conductivity between active materials is improved, but the amount of active material is reduced, resulting in lower discharge capacity
Solution Approach 1:
The patent optimizes the particle size parameters of conductive additives, specifying that they should have an average particle diameter of 0.5 μm or less (preferably 0.1-0.5 μm). This parameter change allows for more efficient distribution and lower percolation thresholds, enabling high electron conductivity with minimal conductive additive content, thus preserving discharge capacity.
3Reliability
If the amount of conductive additive is increased to maintain high electron conductivity, then the electron conductivity is improved, but the active material content is reduced, resulting in lower discharge capacity
Solution Approach 1:
The patent creates a composite electrode structure combining active material particles, binding agent, and conductive additives in specific ratios. The conductive additives are distributed throughout the composite matrix, forming a percolating network that maintains high electron conductivity while allowing maximum active material content. The composite structure enables synergistic effects where each component fulfills its function efficiently.
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 results in a highly filled active material layer with high density and electron conductivity, leading to a battery with increased capacity per electrode volume and improved energy density.
Implementation Method 1
the fibrous carbon-containing compounds form a conductive path and are in contact with the active material layer, enhancing electron conductivity
Implementation Method 2
a positive electrode including an active material such as lithium cobalt oxide (LiCoO2) or lithium iron phosphate (LiFePO4)... lithium ions in the secondary battery move between the positive electrode and the negative electrode through the nonaqueous electrolyte solution and are inserted into or extracted from the active materials
Data Source
AI summary
A conductive additive a small amount of which is used for forming an active material layer with high electron conductivity is provided. An electrode for a secondary battery including a highly filled active material layer having a high density and containing a small amount of a conductive additive is provided. A secondary battery having high capacity per electrode volume is provided. The electrode includes an active material layer containing a plurality of particulate active materials and a plurality of fibrous carbon-containing compounds. Each of the carbon-containing compounds is a high molecular compound. A monomer of the high molecular compound contains at least one selected from thiophene, benzene, pyrrole, aniline, phenol, phthalocyanine, furan, azulene, and a derivative of any of these.