Lithium-Ion Battery Electrode Layout to Limit Anode Lithium Migration
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Solution Overview
Problem
Lithium-ion rechargeable batteries face a reduction in battery capacity due to lithium ions migrating to non-opposing parts of the anode mixture layer, leading to shortened battery life.
Innovation Solution
The battery design includes an anode mixture layer with a larger opposing surface area than the cathode mixture layer, containing between 1000 ppm and 1500 ppm of lithium, and a density of 1.1 g/cc to 1.4 g/cc, along with a lithium transition metal oxide in the cathode mixture layer and a specific Li/M ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the amount of lithium in the cathode mixture layer is increased to improve battery output, then battery capacity increases, but lithium ions migrate to non-opposing parts of the anode mixture layer causing accelerated capacity reduction and shortened battery life
Solution Approach 1:
The anode mixture layer is designed with non-uniform lithium distribution, where the opposing part contains less lithium and the non-opposing part contains more lithium (1000-1500 ppm). This local quality variation prevents lithium ion migration from the cathode to non-opposing regions while maintaining high overall battery capacity.
Solution Approach 2:
Lithium is pre-added to the anode mixture layer at specific concentrations (1000-1500 ppm in the non-opposing part) before battery assembly. This preliminary lithium distribution creates a buffer that prevents excessive lithium ion migration during charging-discharging cycles, thereby extending battery life while allowing high cathode lithium content for high output.
2Reliability
If the anode mixture layer contains greater lithium content to restrict lithium ion escape, then battery life is extended, but the complexity of controlling lithium distribution increases
Solution Approach 1:
The patent specifies precise parameter ranges for lithium content in the anode mixture layer (1000-1500 ppm) and density (1.1-1.4 g/cc). By controlling these parameters within defined ranges, the complex problem of lithium distribution is simplified into measurable and controllable manufacturing specifications.
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 battery output and extends battery life by restricting lithium ion migration to non-opposing regions of the anode, while maintaining high safety and reliability standards.
Implementation Method 1
lithium ions to migrate to a non-opposing part of an anode mixture layer that does not face the cathode mixture layer, instead of moving back and forth between the opposing parts of the cathode mixture layer and the anode mixture layer
Implementation Method 2
a lithium transition metal oxide as a cathode active material
Data Source
AI summary
A lithium-ion rechargeable battery includes an electrode body in which a cathode sheet and an anode sheet are stacked with a separator arranged in between. An opposing surface of an anode mixture layer in the anode sheet is greater in size than an opposing surface of a cathode mixture layer in the cathode sheet. The anode mixture layer contains greater than or equal to 1000 ppm and less than or equal to 1500 ppm of lithium in advance. The anode mixture layer has a density of 1.1 g/cc or greater and 1.4 g/cc or less. The cathode mixture layer contains a lithium transition metal oxide as a cathode active material. A Li/M ratio of a number (Li) of atoms of lithium to a sum (M) of a number of atoms of a transition metal in the lithium transition metal oxide is 1.16 or greater and 1.20 or less.