Negative Electrode Sheet Tuning for Fast-Charge Energy Density
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Solution Overview
Problem
Existing battery technologies face challenges in achieving excellent dynamics performance, long cycle life, and high energy density due to limitations in the design of the negative electrode sheet, particularly in the relationship between porosity, capacity per unit area, and volume median particle diameter of the negative active material, which affect ion movement and energy storage efficiency during fast charging.
Innovation Solution
The negative electrode sheet is optimized by adjusting the porosity, capacity per unit area, and volume median particle diameter of the negative active material within specific ranges (8≤P×[(30-Dv50)/2+2×(10-M)]≤12, ensuring low liquid phase conduction, charge exchange, and solid phase diffusion resistances, thereby enhancing dynamics performance and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the negative electrode structure is optimized for fast charging (high porosity, small particle size), then dynamics performance improves, but energy density decreases
Solution Approach 1:
The patent applies parameter changes by establishing a specific mathematical relationship between porosity P, volume median particle diameter Dv50, and capacity per unit area M through the formula P×[(30-Dv50)/2+2×(10-M)]. This formula allows dynamic adjustment of multiple parameters to achieve optimal balance between fast charging performance (ion movement speed) and energy density, resolving the contradiction by finding the precise parameter combination that satisfies both requirements simultaneously.
2Quantity of substance
If the capacity per unit area of the negative electrode is increased, then energy density improves, but dynamics performance deteriorates due to increased resistance
Solution Approach 1:
The patent uses parameter changes by incorporating capacity per unit area M into the optimization formula P×[(30-Dv50)/2+2×(10-M)]. This allows the capacity to be increased while simultaneously adjusting porosity and particle size to compensate, maintaining low resistance and high charge exchange speed even at higher capacity values. The formula ensures that increased capacity does not come at the expense of dynamics performance.
3Speed
If the porosity of the negative electrode film is increased to reduce liquid phase conduction resistance, then dynamics performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by setting porosity P as a variable in the optimization formula rather than a fixed value. This allows the porosity to be precisely tuned to the minimum necessary level to achieve the required ion conduction speed, avoiding excessive porosity that would complicate manufacturing. The formula P×[(30-Dv50)/2+2×(10-M)]=constant enables finding the optimal porosity value that balances performance improvement with manufacturing feasibility.
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 optimization results in a battery with excellent dynamics performance, long cycle life, and high energy density, as demonstrated by the improved ion movement and energy storage capabilities during fast charging, while maintaining a balanced porosity and particle size that supports both fast charging and prolonged battery life.
Implementation Method 1
the ions pass through the SEI film on the surface of the negative active material and exchange charges with the electrons on the surface of the negative active material, and then the ions enter into the negative active material to perform solid phase diffusion and accumulation
Implementation Method 2
the ions (such as lithium ions, sodium ions and the like) de-intercalated from the positive active material enter into the electrolyte, and then enter into pore channels of the negative porous electrode along with the electrolyte, so that a liquid phase conduction process of the ions is conducted inside the pore channels
Implementation Method 3
the ions pass through the SEI film on the surface of the negative active material and exchange charges with the electrons on the surface of the negative active material
Data Source
AI summary
The present invention provides a negative electrode sheet and a battery. The negative electrode sheet comprises a negative current collector and a negative electrode film provided on at least one surface of the negative current collector and comprising a negative active material, and the negative electrode film satisfies: 4≤P×[(30-Dv50)/2+2×(10-M)]≤20. P represents a porosity of the negative electrode film; Dv50 represents a volume median particle diameter of the negative active material, and a unit is µm; M represents a capacity per unit area of a negative electrode film, and a unit is mAh/cm2. The negative electrode sheet of the present invention has the characteristics of excellent dynamics performance, and the battery of the present invention also has the characteristics of excellent dynamics performance, long cycle life and high energy density at the same time.