Positive Electrode Mix Layer Pore Distribution for Battery Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing nonaqueous electrolyte secondary battery electrodes fail to sufficiently enhance output characteristics due to inhibited ionic conductivity and volume changes during charge/discharge, despite attempts to improve electronic conductivity and ion migration.
Innovation Solution
A positive electrode with a mix layer containing lithium transition metal oxide (Ni content ≥20%) and a pore distribution with peaks at <1 μm and ≥1 μm diameters, enhancing ionic conductivity and maintaining structural stability during charge/discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the positive electrode mix layer uses conventional active materials with low nickel content, then the electrode structure maintains good stability, but the output characteristics and ionic conductivity are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the active material by increasing nickel content to 20% or more in the lithium transition metal oxide, which improves ionic conductivity and output characteristics while maintaining structural stability through the specific pore distribution configuration
Solution Approach 2:
The patent uses composite lithium transition metal oxides containing multiple transition metals (Ni, Co, Mn, etc.) with specific compositional ratios, creating a composite material that achieves both high ionic conductivity and structural stability through synergistic effects of different metal elements
2Reliability
If the positive electrode mix layer has high density to improve electronic conductivity, then electronic conductivity increases, but ion migration is inhibited and ionic conductivity decreases
Solution Approach 1:
The patent creates local quality differences by forming a specific pore distribution with two distinct peaks at different pore diameter ranges, where smaller pores provide pathways for ion migration while larger pores maintain overall electrode porosity and prevent excessive density that would inhibit ion transport
Solution Approach 2:
The patent utilizes porous structure with controlled pore distribution to simultaneously achieve good electronic conductivity through active material contact and high ionic conductivity through adequate pore spaces for ion migration, resolving the contradiction between density-related electronic conductivity and ion migration
3Quantity of substance
If the active material undergoes large volume changes during charge/discharge, then capacity increases, but the pore distribution is disrupted and structural stability decreases
Solution Approach 1:
The patent prepares the electrode structure in advance by forming a robust dual-peak pore distribution and selecting stable lithium transition metal oxide compositions that can accommodate volume changes during charge/discharge, cushioning against structural disruption before it occurs and maintaining pore distribution stability throughout battery operation
Data Source
AI summary
A positive electrode for nonaqueous electrolyte secondary batteries includes a positive electrode current collector and a positive electrode mix layer, formed on the current collector, containing a positive electrode active material. The positive electrode active material mainly contains a lithium transition metal oxide in which the molar ratio of nickel (Ni) to a transition metal component is 20% or more. The positive electrode mix layer contains a plurality of pores and has a first peak of a logarithmic differential pore volume distribution (dV/dlogD) that appears in the range where the pore diameter D is less than 1 μm and a second peak of the logarithmic differential pore volume distribution (dV/dlogD) that appears in the range where the pore diameter D is 1 μm or more in a pore distribution determined by mercury intrusion porosimetry. According to this configuration, a nonaqueous electrolyte secondary battery having excellent output characteristics can be provided.