Negative Electrode Voids for Rapid Charging and Energy Density
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Solution Overview
Problem
Lithium ion batteries face challenges in achieving both high energy density and rapid charging capabilities due to issues with the thinning of electrode components, which can lead to internal short circuits, increased internal resistance, and reduced energy density, as well as insufficient lithium ions around the negative electrode active material during rapid charging.
Innovation Solution
A negative electrode for lithium ion batteries is designed with a negative electrode active material layer that includes voids filled with a non-aqueous liquid electrolyte, ensuring a sufficient proportion of lithium ions are present to support rapid charging, with a battery capacity proportion of lithium ions in the electrolyte to the negative electrode active material ranging from 3% to 17%, optimizing the diffusion rate and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the separator is made thin to enable rapid charging without decreasing energy density, then the charging rate is improved, but internal short circuit is likely to occur due to precipitated lithium
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of lithium ions within the negative electrode active material layer. The layer has higher lithium ion concentration near the separator interface and lower concentration toward the current collector, which locally prevents lithium precipitation at the separator while maintaining overall charging rate performance
Solution Approach 2:
The patent utilizes a porous negative electrode active material layer with controlled void spaces that allow lithium ions to diffuse uniformly throughout the layer. This porous structure prevents localized lithium accumulation that would cause precipitation and short circuits, while still enabling rapid charging through efficient ion transport pathways
2Speed
If the current collector is made thin to enable rapid charging without decreasing energy density, then the charging rate is improved, but the internal resistance of the battery is increased
Solution Approach 1:
The patent applies local quality by optimizing the electrical conductivity distribution within the negative electrode active material layer. The layer is designed with enhanced conductive pathways near the current collector interface to compensate for the reduced current collector thickness, maintaining low internal resistance while enabling rapid charging
3Quantity of substance
If the amount of negative electrode active material per unit volume is increased to increase energy density, then the energy density is improved, but the amount of non-aqueous liquid electrolyte around the negative electrode active material is relatively decreased, and rapid charging cannot be coped with
Solution Approach 1:
The patent utilizes a porous negative electrode active material layer with optimized porosity (30-70%) that maintains sufficient void spaces for electrolyte penetration even at high active material densities. This porous structure ensures adequate electrolyte distribution throughout the layer, enabling rapid charging while achieving high energy density through increased active material content
Solution Approach 2:
The patent employs composite material structure by combining negative electrode active material particles with conductive carbon matrix and binder materials in specific ratios. This composite approach allows high active material loading for energy density while maintaining porosity and electrolyte accessibility for rapid charging performance
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 enables lithium ion batteries to achieve high energy density while maintaining excellent rapid charging characteristics, as the sufficient lithium ions around the active material enhance charging efficiency and prevent internal resistance issues.
Implementation Method 1
the voids are filled with the non-aqueous liquid electrolyte... ensuring a sufficient proportion of lithium ions are present to support rapid charging... enhance charging efficiency
Data Source
AI summary
To provide a negative electrode for a lithium ion battery having high energy density and excellent rapid charging characteristics.A negative electrode for a lithium ion battery, the negative electrode including a negative electrode current collector, a negative electrode active material layer formed on the surface of the negative electrode current collector, and a non-aqueous liquid electrolyte including an electrolyte containing lithium ions and a non-aqueous solvent, in which the negative electrode active material layer includes a negative electrode active material and voids, the voids are filled with the non-aqueous liquid electrolyte, and a proportion of the battery capacity based on a total amount of lithium ions in the non-aqueous liquid electrolyte existing in the negative electrode active material layer with respect to the battery capacity based on a total amount of the negative electrode active material is 3% to 17%.