Layered Graphite Electrode Structure for Fast-Charging Li-Ion Batteries
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving improved adhesive force, high temperature performance, normal temperature performance, and rapid charging performance due to issues with binder and conductive material distribution in multi-layered electrodes, leading to increased internal resistance and reduced capacity.
Innovation Solution
The electrode for lithium secondary batteries is designed with a multi-layered structure where the upper layer contains artificial graphite with a specific surface area of 0.6 to 1.4 m²/g and the lower layer contains expansion-suppressing natural graphite with a specific surface area of 1.4 to 3.6 m²/g, along with a binder concentration ratio of 1/3 to 1.5, ensuring optimal adhesive force and performance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content of the binder is increased to improve adhesive force, then adhesive force is improved, but internal resistance increases and capacity decreases
Solution Approach 1:
The patent applies local quality by creating a multi-layered electrode structure where different layers have different binder contents optimized for their specific functions. The lower layer (closer to current collector) has higher binder content for strong adhesion, while the upper layer has lower binder content for better conductivity and capacity, thus resolving the contradiction between adhesive force and internal resistance.
Solution Approach 2:
The electrode is segmented into multiple layers with distinct compositions. By dividing the electrode material into separate layers with different binder concentrations, the patent allows each layer to optimize its properties independently, achieving both high adhesive force (in binder-rich lower layers) and low internal resistance (in binder-poor upper layers).
2Power
If the content of the conductive agent is increased to improve output characteristics, then output characteristics are improved, but adhesive force is lowered and capacity is reduced
Solution Approach 1:
The patent uses local quality by assigning different conductive agent contents to different layers. The upper layer has higher conductive agent content for improved output characteristics and electron transport, while the lower layer has lower conductive agent content but higher binder content to maintain strong adhesive force, thus resolving the contradiction between output characteristics and adhesive force.
3Reliability
If a multi-layered structure is used to improve adhesive force and performance, then adhesive force and performance are improved, but device complexity increases
Solution Approach 1:
The patent segments the electrode into multiple layers with specific compositions to achieve improved performance. While this increases structural complexity, the segmentation allows each layer to be optimized for specific functions (adhesion, conductivity, capacity), ultimately resolving the contradiction by achieving superior performance that justifies the increased complexity.
Data Source
AI summary
The present disclosure relates to an electrode for a lithium secondary battery and a lithium secondary battery including the same, the electrode including: a current collector; and an electrode material layer containing an active material and a binder that is formed on at least one surface of the current collector, wherein, when the electrode material layer is divided in half based on the thickness, the upper layer located away from the current collector and corresponding to the thickness of 1/2 is referred to as an electrode material layer A, and the lower layer located close to the current collector and corresponding to the thickness of 1/2 is referred to as an electrode material layer B, each of the electrode material layer A and the electrode material layer B contains one or more active material layers, and satisfies all of the conditions (1) to (3) described in claims