Positive Electrode Conductive Agent Distribution for Battery Cycle Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte batteries face challenges in achieving high energy density while maintaining excellent cycle properties due to insufficient electrical conduction networks and uneven distribution of active materials, leading to resistance deviations and reduced long-term performance.
Innovation Solution
A positive electrode structure with a specific distribution of conductive agents, including carbonaceous materials like acetylene black and graphite, optimized through Raman spectroscopy to ensure a uniform electronic conduction network, achieving a ratio of occupancy areas between 1.5 to 5, and a distance ratio of 0.9 to 1.1 between active material and conductive agent particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high Ni content compounds are used to increase capacity, then energy density is improved, but crystal structure stability deteriorates and cycle property decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central portion contains high Ni content (0.8-0.95) for high capacity, while the outer peripheral portion has reduced Ni content (0.5-0.8) for structural stability. This spatial differentiation of composition allows simultaneous achievement of high energy density and excellent cycle property by assigning different functional qualities to different regions of the same particle.
2Quantity of substance
If electrode density is increased to improve energy density, then capacity is improved, but electrical conduction network becomes insufficient and resistance distribution deviates
Solution Approach 1:
The patent creates local quality differences in the electrode structure by forming a porous outer peripheral layer with lower density (1.8-2.2 g/cm³) compared to the inner core (2.2-2.6 g/cm³). This porous structure locally enhances electrical conduction and electrolyte penetration at the particle surfaces, ensuring uniform resistance distribution while maintaining high overall energy density through the dense core region.
3Quantity of substance
If auxiliary members amount is decreased to improve energy density, then capacity is improved, but porosity decreases and Li ion concentration deviation increases
Solution Approach 1:
The patent utilizes porous materials by intentionally creating a porous outer peripheral layer with controlled porosity (30-70%) around the dense core particles. This porous structure acts as a buffer zone that facilitates uniform Li ion diffusion and concentration distribution throughout the electrode, eliminating the need for excessive auxiliary members while maintaining high energy density and preventing Li ion concentration deviation.
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 enhances energy density and cycle properties by ensuring uniform resistance distribution and preventing material utilization deviations, resulting in improved battery performance and capacity retention.
Implementation Method 1
a first conductive agent having a D-band appearing at 1350 ± 10 cm⁻¹ in a Raman chart of the positive electrode material layer
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
According to one embodiment, there is provided a nonaqueous electrolyte battery (10). The nonaqueous electrolyte battery (10) includes a positive electrode (3), a negative electrode (4), and a nonaqueous electrolyte. The positive electrode (3) includes a positive current collector (3a) and a positive electrode material layer (3b) formed on the positive electrode current collector (3a). The positive electrode material layer (3b) includes a positive electrode active material and a first conductive agent. In a mapping image for the positive electrode material layer (3b), a ratio of an occupancy area of the first conductive agent to an occupancy area of the positive electrode active material is from 1.5 to 5.