Mixed Positive Electrode Material Conductivity
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Solution Overview
Problem
Lithium secondary batteries face limitations in output characteristics and available state of charge (SOC) area due to high electrical resistance and low conductivity in mixed positive electrode materials containing 3-component system layered oxides and olivine structure metal oxides, despite attempts to improve conductivity by adding large amounts of conductive materials.
Innovation Solution
Simultaneous coating of two or more conductive materials with different particle sizes and shapes, such as circular-shaped conductive carbon and plate-shaped graphite, to uniformly distribute conductive material within the mixed positive electrode material, reducing electrical resistance and enhancing conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mixture of LiFePO4 and 3-component system layered oxide is used as positive electrode active material, then stability and cost are improved, but electrical resistance increases and output characteristics deteriorate
Solution Approach 1:
The patent uses a composite material system combining LiFePO4 (olivine structure) with 3-component system layered oxide (Li[Ni1/3Co1/3Mn1/3]O2). This composite structure allows the stable LiFePO4 to provide structural stability while the layered oxide maintains high conductivity and output characteristics, resolving the contradiction between stability and power output.
2Power
If a large amount of conductive material is added to improve conductivity, then electrical resistance decreases, but energy density is significantly reduced
Solution Approach 1:
The patent applies local quality by selectively adding conductive materials (acetylene black and graphite) in specific amounts and distributions within the positive electrode mixture. Rather than uniformly distributing conductive material throughout, the conductive agents are locally optimized to provide sufficient conductivity pathways while minimizing the overall volume occupied by non-active materials, thus preserving energy density.
Data Source
Figure 1
AI summary
The present invention relates to a positive electrode active material for improving output and to a lithium secondary battery comprising same. More particularly, the present invention relates to a high-capacity positive electrode active material and to a lithium secondary battery comprising same, wherein graphite and conductive carbon, the particles of which have different shapes and sizes, are simultaneously coated as a conductive material to a mixture positive electrode material of layered ternary metal oxide containing lithium expressed by the following [chemical formula 1] and LiFePO4 having an olivine structure, thus improving expression of high resistance and insufficiency of conductivity of the ternary metal oxide containing lithium, caused by the difference in particle size or surface area between the ternary metal oxide containing lithium expressed by the following [chemical formula 1] and LiFePO4 having an olivine structure. Thus, the problem of the low output of the positive electrode active material containing the positive material may be improved, and simultaneously the positive electrode active material has a wide available SOC region. [Chemical formula 1] Li1+aNixCoyMn1-x-yO2, 0≤a<0.5, 0