Positive Electrode Sheet Composition for Thick-Layer Battery Conductivity
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Solution Overview
Problem
Existing non-aqueous electrolytic solution secondary batteries face challenges in achieving both high capacity and output characteristics due to issues with electron conductivity in the positive electrode active material layer, which are exacerbated by high viscosity and aggregation of solid particles in the slurry, leading to non-uniform layers and varying battery performance.
Innovation Solution
A positive electrode sheet is designed with a specific surface area and content relationship of the conductive auxiliary agent in the positive electrode active material layer, ensuring electron conductivity within a controlled range, allowing for a thick film formation that enhances both capacity and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the slurry concentration is increased to improve manufacturing efficiency, then the drying time is reduced, but the viscosity increases and solid particles aggregate leading to non-uniform layers
Solution Approach 1:
A dispersant is introduced as an intermediary substance in the slurry to prevent aggregation of solid particles (positive electrode active material and conductive auxiliary agent). The dispersant mediates between the high concentration requirements for efficiency and the uniformity requirements for quality, enabling stable dispersion even at high solid content levels.
Solution Approach 2:
The chemical composition parameters of the slurry are modified by adding specific dispersants and adjusting the ratio of conductive auxiliary agent to positive electrode active material. These parameter changes allow the slurry to maintain low viscosity and stable dispersion at high concentrations, resolving the contradiction between productivity and manufacturing precision.
2Power
If the content of conductive auxiliary agent is increased to improve electron conductivity, then the output characteristics improve, but the manufacturing cost and device complexity increase
Solution Approach 1:
The optimal content ratio of conductive auxiliary agent to positive electrode active material is determined through parameter optimization. By finding the precise quantitative relationship (specific ranges) that achieves sufficient electron conductivity without excessive addition, the solution balances power improvement with composition simplicity.
Solution Approach 2:
Instead of using complex conductive networks or multiple conductive materials, the invention uses a simplified approach by optimizing the distribution and content of a single conductive auxiliary agent type, copying the essential function of complex conductive structures through a simpler means.
3Quantity of substance
If the positive electrode active material layer is made thicker to increase capacity, then the energy density improves, but the electron conductivity decreases leading to poorer output characteristics
Solution Approach 1:
The conductive auxiliary agent is distributed throughout the positive electrode active material layer to create local conductive pathways. This local quality enhancement ensures that even in thicker layers, electron conductivity is maintained at sufficient levels, allowing both high capacity and good output characteristics.
Solution Approach 2:
The positive electrode active material layer is formulated as a composite material system combining positive electrode active material, conductive auxiliary agent, and dispersant. This composite structure enables the layer to simultaneously achieve high capacity (through adequate thickness) and high electron conductivity (through the conductive auxiliary agent network).
Data Source
AI summary
Provided are a positive electrode sheet obtained by laminating a positive electrode collector and a positive electrode active material layer, in which the positive electrode active material layer contains a positive electrode active material and a conductive auxiliary agent, and has a thickness of 120 μm or more, a specific surface area x (m2/g) of the conductive auxiliary agent and a content y (% by mass) of the conductive auxiliary agent in the positive electrode active material layer satisfy 5≤x×y≤420 and 100≤x, and an electron conductivity z (mS/cm) of the positive electrode active material is 1.0 or more; and a non-aqueous electrolytic solution secondary battery including the sheet as a positive electrode.