Porous Electrode Domain Structures for Battery Cycle Life
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges with charge/discharge cycle characteristics and capacity due to internal stress and cracking in porous negative electrodes, particularly those formed as columnar structures on a collector surface, which limits their battery life and capacity.
Innovation Solution
The electrode is formed as an assembly of porous domain structures with a polygonal shape without acute angles, each having a maximum diameter of 120 μm or less, arranged apart on a collector surface, which alleviates internal stress and enhances charge/discharge cycle characteristics and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous negative electrode is formed as columnar structures on a collector surface, then charge/discharge cycle characteristics are improved, but battery capacity is reduced due to unused spaces
Solution Approach 1:
The electrode is divided into multiple porous domain structures with specific size ranges (1-100 μm diameter) arranged in an array pattern. This segmentation allows the electrode to maintain the stress-alleviating benefits of porous structures while increasing the overall active material content on the collector surface, thus improving both cycle characteristics and capacity.
Solution Approach 2:
The porous domain structures are designed with specific local characteristics including controlled porosity (30-80%), specific size ranges, and array arrangement patterns. These localized quality parameters optimize both the mechanical stress distribution (improving cycle life) and the electrochemically active surface area (improving capacity).
2Quantity of substance
If metal material is used for negative electrode to obtain capacity larger than 372 mAh/g, then charge/discharge capacity is improved, but internal stress causes pulverization and reduces electrode life
Solution Approach 1:
Metal materials (such as Si, Ge, Sn, or their alloys) are formed into porous domain structures with controlled porosity (30-80%). The porous structure provides internal space to accommodate volume expansion during lithium alloying, significantly reducing internal stress and preventing pulverization. This allows the electrode to maintain high capacity (>372 mAh/g) while achieving excellent cycle life.
Solution Approach 2:
The metal material is segmented into multiple small porous domain structures (1-100 μm diameter) rather than using a single large structure. This segmentation reduces the overall stress burden on each individual domain and prevents crack propagation, thereby maintaining electrode integrity over many charge/discharge cycles while preserving high capacity.
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 charge/discharge cycle characteristics and secondary battery capacity by reducing internal stress and cracking, maintaining high discharge capacity even after multiple cycles.
Implementation Method 1
lithium ions are reduced into lithium and stored into the negative electrode
Implementation Method 2
lithium existing in a negative electrode is oxidized into lithium ions and released
Implementation Method 3
lithium ions move between the positive electrode and the negative electrode
Data Source
AI summary
An electrode having excellent charge/discharge cycle characteristics and which is capable of improving a secondary battery capacity. An electrode is formed on the surface of a collector as an assembly of multiple porous domain structures that are apart from each other, the porous domain structures each having a polygonal shape without an acute angle in a planar view, the polygonal shape having a maximum diameter of 120 μm or less.