Electrode Assembly Capacity Balancing for Longer Battery Cycle Life
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Solution Overview
Problem
Secondary batteries face challenges in maintaining a longer cycle life due to structural changes, electrolyte decomposition, and SEI film formation, leading to active ion consumption and capacity attenuation.
Innovation Solution
The electrode assembly features a positive electrode plate with two film layers and a negative electrode plate, where the capacity and resistance ratios are optimized to improve voltage response speed and potential difference, allowing pre-stored active ions to supplement consumption, thereby extending cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If active ions are intercalated and deintercalated during charge and discharge, then battery capacity is maintained, but active ions are consumed and capacity attenuates over time
Solution Approach 1:
The patent applies preliminary action by pre-storing active ions in the positive electrode film layer before battery operation. The positive electrode is designed with higher initial capacity than the negative electrode, creating a capacity differential that allows the positive electrode to reservoir excess active ions. During cycling, these pre-stored ions gradually supplement the negative electrode, compensating for ion consumption and delaying capacity decay.
Solution Approach 2:
The patent employs parameter changes by optimizing the capacity ratio between positive and negative electrodes, specifically setting the positive electrode capacity to 1.05-1.20 times that of the negative electrode. This parameter adjustment creates the necessary capacity differential to enable the preliminary action mechanism, transforming the electrode design from equal capacity to asymmetric capacity distribution.
2Reliability
If the positive electrode capacity is increased to provide pre-stored active ions, then cycle life is extended, but energy density may be compromised
Solution Approach 1:
The patent resolves this contradiction through precise parameter optimization, setting the positive electrode capacity to 1.05-1.20 times the negative electrode capacity. This narrow range is sufficient to provide pre-stored active ions for cycle life extension while minimizing the capacity differential to preserve energy density. The parameter control ensures neither extreme is reached.
Solution Approach 2:
The patent applies partial action by providing just enough excess capacity in the positive electrode (5-20% over the negative electrode) to achieve the cycle life extension goal, rather than significantly increasing positive electrode capacity. This partial excess is sufficient to reservoir the needed active ions without substantially compromising energy density.
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 configuration enhances the cycle life and energy density of secondary batteries by ensuring sufficient pre-stored active ions are gradually released, delaying capacity decay.
Implementation Method 1
During the charge and discharge process of secondary batteries, active ions (such as lithium ions) are intercalated and deintercalated between a positive electrode and negative electrodes
Implementation Method 2
the positive electrode plate satisfies 0≤R4/R3−R2/R1, in which R1 represents resistance of the first positive electrode film layer in Ω, R2 represents resistance of the second positive electrode film layer in Ω
Data Source
AI summary
An electrode assembly, secondary battery, battery module, battery pack and electrical device are provided. In some embodiments, the electrode assembly comprises a positive electrode plate, a negative electrode plate and a separator disposed between the positive electrode plate and the negative electrode plate, the positive electrode plate satisfies 0<CAP1/CAP2<1, in which CAP1 represents capacity of the first positive electrode film layer in Ah, CAP2 represents capacity of the second positive electrode film layer in Ah, and the electrode assembly satisfies R4/R3−R2/R1≥0, in which R1 represents resistance of the first positive electrode film layer in Ω, R2 represents resistance of the second positive electrode film layer in Ω, R3 represents resistance of the first negative electrode film layer in mΩ and R4 represents resistance of the second negative film layer in mΩ. The present applicant may extend the cycle life of the secondary battery.