Positive Electrode Tab Layout for Lower Li-Ion Discharge Heating
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Solution Overview
Problem
Lithium-ion batteries experience excessive temperature rise during high-rate discharge, affecting battery life and safety.
Innovation Solution
An electrochemical apparatus with a positive electrode active material containing at least 60% nickel, a balanced ratio of positive electrode tabs to layers, and controlled thickness of the active material layer and current collector, along with carbon nanotubes, reduces temperature rise during high-rate discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode active material layer thickness is increased to improve capacity, then the battery capacity increases, but the temperature rise during high-rate discharge worsens
Solution Approach 1:
The patent optimizes the thickness of the positive electrode active material layer to a specific range (10-30 μm) to balance capacity and heat generation. This parameter optimization ensures sufficient active material for high capacity while limiting the thickness to reduce internal resistance and heat accumulation during high-rate discharge.
Solution Approach 2:
The patent uses composite positive electrode active materials containing nickel, cobalt, and manganese elements with specific molar ratios. This composite material structure provides high capacity while the synergistic effects of different elements help manage heat generation and improve thermal stability during discharge.
2Temperature
If the number of positive electrode tabs is increased to reduce current density and temperature rise, then the temperature rise during discharge decreases, but the device complexity increases
Solution Approach 1:
The patent divides the positive electrode into multiple tabs instead of using a single tab structure. This segmentation distributes the current collection points, reducing current density at each tab and thereby reducing heat generation and temperature rise during high-rate discharge.
Solution Approach 2:
The patent optimizes the ratio of the number of positive electrode tabs to the number of electrode plate layers within a specific range (0.25≤a/b≤1.25). This dimensional optimization balances the distribution of current paths and heat generation across the electrode structure, achieving effective temperature control without excessive complexity.
3Quantity of substance
If high-nickel positive electrode active material is used to improve capacity, then the battery capacity increases, but the temperature rise during discharge worsens
Solution Approach 1:
The patent precisely controls the molar percentage of nickel in the positive electrode active material (X≥60%) while simultaneously optimizing the thickness of the active material layer (10-30 μm). This dual parameter optimization allows the battery to achieve high capacity from the high-nickel material while the controlled thickness limits the total heat generation during discharge.
Solution Approach 2:
The patent applies different material compositions and thicknesses at different locations within the positive electrode. The high-nickel active material is used to maximize capacity, while the controlled local thickness (10-30 μm) ensures that heat generation remains manageable during high-rate discharge operations.
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 solution effectively reduces temperature rise, enhancing safety and stability performance of lithium-ion batteries by optimizing the positive electrode structure.
Implementation Method 1
As important electrical energy storage devices, the storage performance and safety performance of electrochemical apparatus need to be strictly controlled
Implementation Method 2
the current lithium-ion batteries tend to have a rapid temperature rise during high-rate discharge
Data Source
AI summary
An electrochemical apparatus includes an electrode assembly, a positive electrode tab, and a negative electrode tab. In the electrode assembly, a separator is disposed between a positive electrode plate and a negative electrode plate. The positive electrode tab is connected to the positive electrode plate, and the negative electrode tab is connected to the negative electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer disposed on its surface. The number a of the positive electrode tabs and the number b of layers of the positive electrode plate satisfy the relationship 0.25≤a/b≤1.25. A molar percentage X of nickel in the positive electrode active material satisfies the relationship X≥60%. A thickness h1 of the positive electrode active material layer satisfies: 10 μm≤h1≤30 μm.