Secondary Battery Reaction Estimation for Thick Electrode Charging
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Solution Overview
Problem
High capacity secondary batteries experience non-uniformity of electrochemical reactions due to the thickness of the electrode active material layer, leading to reduced energy density and inefficient charge performance, as only a portion of the electrode material participates effectively in the reaction.
Innovation Solution
A battery cell structure with thin electrodes separated by a porous current collector is used, allowing for the insertion of a reference electrode to measure current and voltage differences between layers, enabling estimation of lithium ion reactivity in the thickness-wise direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the electrode active material layer is increased to improve battery capacity, then the energy density of the battery cell decreases and electrochemical reaction uniformity deteriorates
Solution Approach 1:
The patent divides the thick electrode into multiple thin electrode layers separated by porous current collectors. This segmentation allows each thin layer to maintain uniform electrochemical reaction while collectively providing high battery capacity, resolving the contradiction between quantity of substance and manufacturing precision.
2Productivity
If a high-loading electrode is used to improve battery performance, then only part of the electrode active material participates in the battery reaction, resulting in insufficient performance improvement
Solution Approach 1:
By segmenting the high-loading electrode into multiple thin layers with porous current collectors in between, the patent ensures that all active material throughout the electrode structure participates uniformly in the battery reaction, eliminating the non-uniformity problem of conventional thick electrodes.
Solution Approach 2:
The porous current collectors enable electrolyte penetration throughout the electrode structure, ensuring uniform lithium ion distribution and reaction participation across all active material, thereby achieving both high loading and uniform reaction.
3Quantity of substance
If the thickness of the electrode active material layer is increased, then boosting charge characteristics deteriorate due to concentration gradient of lithium ions
Solution Approach 1:
Segmenting the thick electrode into thin layers reduces the diffusion distance for lithium ions in each layer, eliminating concentration gradients and enabling fast boosting charge while maintaining high electrode loading.
Solution Approach 2:
The porous current collectors facilitate rapid electrolyte distribution and lithium ion transport throughout the electrode structure, enabling fast charging kinetics even with high electrode loading.
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 method allows for improved design optimization by estimating reaction uniformity, enhancing the boosting charge performance of high-loading electrodes.
Implementation Method 1
a battery cell having a structure of first electrode/separator/reference electrode/separator/second electrode
Implementation Method 2
When current or voltage is applied to a secondary battery, a concentration gradient of lithium ions takes place in the electrode
Implementation Method 3
an electrochemical reaction preemptively occurs on the surface layer of the electrode that contacts with an electrolyte solution, and as a consequence, lithium metal is deposited on the surface layer
Data Source
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AI summary
The present disclosure is intended to design a secondary battery with improved boosting charge performance by estimating reaction in the thickness-wise direction of the electrode, and provides a method or estimating reaction of a secondary battery including (a) preparing a battery cell having a structure of first electrode/separator/reference electrode/separator/second electrode, wherein the second electrode has a structure of upper layer/porous film/lower layer, (b) setting a charging condition to estimate reaction of the battery cell, (c) measuring voltage and current of each of the upper layer, the lower layer and the battery cell while the set charging condition is reached, (d) after the charging condition, measuring an open-circuit voltage of the upper layer, the lower layer and the battery cell, and (e) comparatively analyzing a capacity obtained using the measured current with the measured open-circuit voltage, and a battery cell used for the same.