Lithium Battery Positive Electrode Pore Distribution
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving superior high-rate and cycle characteristics due to inadequate conductivity in the positive electrode mix layer, particularly with insufficient pore distribution and conductive material content, leading to increased internal resistance during repeated high-rate charge and discharge.
Innovation Solution
A lithium secondary battery design featuring a positive electrode mix layer with two distinct pore size peaks, one large and one small, in the pore distribution curve, optimized by incorporating conductive materials like carbon powder, which enhances electrolyte retention and ion migration efficiency, thereby improving conductivity and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pore size distribution in the positive electrode mix layer is not optimized, then good conductive paths cannot be formed, but increasing pore volume may reduce structural integrity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pore size distribution parameters, setting two specific peak ranges (first peak: 0.01-0.1 μm, second peak: 0.1-10 μm). This optimized parameter configuration ensures that pores are sufficiently small to maintain structural integrity while large enough to allow conductive material penetration and electrolyte wettability, thereby forming good conductive paths without compromising strength.
2Power
If the positive electrode mix layer structure is optimized for high-rate discharge, then power output is improved, but cycle characteristic and durability may deteriorate
Solution Approach 1:
The patent applies local quality by creating different pore size regions within the positive electrode mix layer. The first peak region (0.01-0.1 μm) provides fine pores for good structural stability and electrolyte retention, while the second peak region (0.1-10 μm) provides larger pores for efficient ion transport during high-rate discharge. This local differentiation allows the electrode to simultaneously achieve high power output and good cycle characteristic.
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
The optimized pore distribution and conductive material composition in the positive electrode mix layer result in enhanced battery performance, including improved high-rate and cycle characteristics, reduced internal resistance, and efficient ion migration, making the battery suitable for high-output applications like vehicle-mounted power sources.
Implementation Method 1
a positive electrode mix layer that has, on the surface of the collector, a positive electrode active material and a conductive material
Implementation Method 2
the positive electrode mix layer has two peaks, large and small, of differential pore volume over a pore size ranging from 0.01 μm to 10 μm in a pore distribution curve measured by a mercury porosimeter
Data Source
AI summary
A lithium secondary battery of the present invention has a positive electrode is provided with a positive electrode mix layer that includes a positive electrode active material and a conductive material. The positive electrode mix layer has two peaks, large and small, of differential pore volume over a pore size ranging from 0.01 μm to 10 μm in a pore distribution curve measured by a mercury porosimeter. A pore size of the smaller peak B of the differential pore volume is smaller than a pore size of the larger peak A of the differential pore volume.