Layered Positive Electrode Material for Higher Li-Ion Capacity
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Solution Overview
Problem
Existing lithium-ion batteries with positive electrode active material layers containing a positive electrode active material and a lithium alloy often fail to achieve desired battery capacity.
Innovation Solution
A positive electrode active material layer is developed, comprising a positive electrode active material coated with a carbon material, a lithium alloy of lithium and a metal element with an alloying potential of 0.5 V (vs. Li/Li+) or more, where the lithium alloy is arranged on the surface closer to the positive electrode current collector and/or the separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium alloy is mixed with positive electrode active material to supplement lithium ions, then battery capacity can be improved, but the contact between carbon material coating and lithium alloy may cause harmful reactions reducing capacity
Solution Approach 1:
The positive electrode active material layer is segmented into multiple layers: a first layer containing the lithium alloy and a second layer containing the positive electrode active material coated with carbon material. This spatial segmentation prevents direct contact between the carbon material and lithium alloy while maintaining the beneficial lithium ion supplementation effect, thereby resolving the harmful reaction issue while preserving capacity improvement
Solution Approach 2:
The patent introduces an intermediary structure (the layered configuration with separator between first and second layers) that mediates the interaction between lithium alloy and carbon material. The lithium alloy layer acts as an intermediary that supplies lithium ions to the positive electrode active material through the separator without direct contact, preventing harmful reactions while achieving capacity enhancement
2Quantity of substance
If lithium alloy is dispersed throughout the positive electrode active material layer, then lithium ion supplementation is maximized, but the risk of short circuits and reduced durability increases
Solution Approach 1:
The lithium alloy is segmented into a distinct first layer separated from the positive electrode active material layer by a separator. This segmentation concentrates the lithium ion supplementation function in the first layer while isolating it from direct contact with carbon materials in the second layer, thereby maintaining durability and reducing short circuit risk while achieving effective lithium ion supplementation
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 improves battery capacity by reducing the contact area between the carbon material and the lithium alloy, enhancing durability and reducing the likelihood of short circuits.
Implementation Method 1
Some of the lithium ions supplied from a positive electrode active material of a lithium-ion battery react with an electrolyte on the surface of a negative electrode active material layer and are consumed to form a solid electrolyte interface (SEI)
Implementation Method 2
the positive electrode active material is coated with a carbon material
Data Source
AI summary
The present disclosure provides a positive electrode active material layer which can improve battery capacity, a lithium-ion battery comprising such a positive electrode active material layer, and a method for manufacturing such a positive electrode active material layer. The positive electrode active material layer 20 of the present disclosure comprises a positive electrode active material 21a and a lithium alloy 22a of lithium and a metal element. The positive electrode active material is coated with a carbon material, the metal element has an alloying potential with lithium of 0.5V (vs. Li/Li+) or more, and the lithium alloy is arranged on a surface of closer to the positive electrode current collector and/or separator of the positive electrode active material layer. A lithium-ion battery of the present disclosure comprises a positive electrode active material layer of the present disclosure, which is interposed between a positive electrode current collector and a separator.