Secondary Lithium Battery Anode Binder Sizing for Cycle Life
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Solution Overview
Problem
Secondary lithium batteries face challenges in achieving good cycle-life characteristics due to inadequate adherence between the anode active material and the current collector, which affects battery performance and energy density.
Innovation Solution
An anode for secondary lithium batteries is designed with an anode active material having a sphericity of 0.83 to 0.91 and a binder with an average particle diameter (D50) of 180 nm to 450 nm, preventing binder penetration and enhancing adherence between the active material layer and the current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a binder with small particle diameter is used to improve adherence, then the binder can penetrate into surface gaps of active material, but the effective bonding area is reduced and cycle-life deteriorates
Solution Approach 1:
The patent changes the particle diameter parameter of the binder from conventional small sizes (e.g., 100 nm or less) to a larger range of 150 nm to 500 nm, with preference for 200 nm to 400 nm. This parameter change prevents binder penetration into surface gaps while maintaining effective bonding area, thereby improving both adherence and cycle-life characteristics
Solution Approach 2:
The patent optimizes the local quality of the binder by controlling its particle size distribution to match the surface characteristics of the active material. The binder particles are sized to sit on surface irregularities rather than penetrate them, creating optimal local bonding conditions at the interface between current collector and active material
2Reliability
If the binder particle diameter is increased to prevent penetration, then the effective bonding area increases, but the adherence mechanism may be compromised
Solution Approach 1:
The patent identifies and optimizes the critical parameter of binder particle diameter, establishing the optimal range of 150 nm to 500 nm. Within this range, the binder maintains sufficient surface area for bonding while preventing penetration, achieving a balance between effective bonding area and adherence strength
Solution Approach 2:
The patent uses spheroidized active material with controlled surface characteristics as a template to determine the optimal binder particle size. The binder particles are sized to complement the surface topology of the active material, creating optimal interfacial bonding without penetration
Data Source
AI summary
Disclosed are a secondary lithium battery anode and a secondary lithium battery including same, the secondary lithium battery anode comprising a current collector and an anode active material layer located on at least one surface of the current collector, wherein the anode active material layer includes an anode active material, which has sphericity of 0.83 to 0.91, and a binder, which has an average particle diameter (D50) of 180 nm to 450 nm.