Electrode Porosity Control for Battery Cycle Power Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Energy storage devices experience a decrease in input power retention due to cracking of positive active material particles and graphite particles during charge-discharge cycles, leading to reduced efficiency.
Innovation Solution
The energy storage device incorporates positive and negative active material layers with specific porosities, where the positive active material layer has an internal porosity of 15% or less and the graphite particle has an internal porosity of 2% or less, along with a pressed electrode assembly to enhance electrical contact and reduce cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If graphite particles with high internal porosity are used as negative active material, then the initial charge capacity is improved, but particle cracking occurs during charge-discharge cycles leading to decreased input retention
Solution Approach 1:
The patent applies parameter changes by strictly controlling the internal porosity of graphite particles to 2% or less, transforming the physical structure parameter to prevent cracking while maintaining charge capacity. This parameter optimization resolves the contradiction between initial performance and cycle stability.
2Productivity
If positive active material particles with high internal porosity are used, then the reaction activity and charge capacity are improved, but particle cracking occurs during pressing and charge-discharge cycles leading to decreased input retention
Solution Approach 1:
The patent controls the internal porosity of positive active material particles to 15% or less, optimizing the structural parameter to prevent cracking during pressing and cycling while maintaining adequate reaction activity. This parameter control resolves the contradiction between productivity and reliability.
3Power
If the electrode assembly is pressed to enhance electrical contact, then the input power is improved, but particle cracking is promoted leading to decreased input retention after cycling
Solution Approach 1:
The patent performs preliminary action by pre-compressing graphite particles to reduce their internal porosity to 2% or less before assembly. This preliminary structural optimization prevents cracking during subsequent pressing operations, allowing the electrode assembly to be pressed for enhanced electrical contact without compromising particle integrity and input retention.
Data Source
AI summary
An energy storage device according to an aspect of the present invention includes an electrode assembly in which a positive electrode including a positive active material layer and a negative electrode including a negative active material layer are stacked with each other with a separator interposed therebetween, in which the positive active material layer contains a positive active material particle, and the positive active material particle has an internal porosity of 15% or less, and the negative active material layer contains a graphite particle, and the graphite particle has an internal porosity of 2% or less.