Battery Current Collector Recesses to Prevent Active Material Fall-Off
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Solution Overview
Problem
Lithium-ion batteries experience a significant reduction in service life and power performance due to the gradual fall-off of positive and negative electrode active materials from current collectors during long-term charge-discharge cycling, which also compromises the protective oxide layer on the collectors, leading to safety issues.
Innovation Solution
Incorporating a recess structure into the current collectors of the electrodes, where the recess depth and conductivity of the electrolyte satisfy a specific relationship, allowing active material particles to embed within the recesses and maintain effective contact, thereby preventing fall-off and enhancing lithium ion transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrode active material is applied on flat current collector surface, then manufacturing is simple, but active material falls off during long-term cycling
Solution Approach 1:
The current collector is designed with recess structures creating a porous-like surface topology. These recesses provide anchoring sites for electrode active material particles, preventing fall-off during cycling while maintaining manufacturing feasibility through techniques like electrochemical etching or mechanical embossing.
Solution Approach 2:
The invention transitions from a two-dimensional flat current collector surface to a three-dimensional structured surface with recesses. This dimensional change provides depth for particle embedding, enhancing mechanical interlocking between the current collector and electrode active material without significantly increasing overall device complexity.
2Reliability
If recess structure is added to current collector, then active material fall-off is prevented, but manufacturing complexity increases
Solution Approach 1:
The recess structures are defined by specific parameter ranges (depth, width, spacing) that can be controlled during manufacturing. By optimizing these parameters, the invention achieves reliable particle anchoring while using standard manufacturing techniques like electrochemical etching, embossing, or additive manufacturing, balancing performance with manufacturability.
3Ease of manufacture
If electrode active material particles are large, then manufacturing is easier, but contact effectiveness with current collector decreases
Solution Approach 1:
The current collector surface is designed with localized recess structures that provide enhanced contact areas. These recesses create local zones of improved mechanical interlocking and electrical contact, allowing the use of larger electrode active material particles while maintaining effective contact through the three-dimensional anchoring geometry.
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 solution significantly improves the cycle life and power performance of lithium-ion batteries by preventing active material fall-off, reducing internal polarization, and maintaining the integrity of the protective oxide layer, leading to enhanced service life and safety.
Implementation Method 1
Incorporating a recess structure into the current collectors of the electrodes, where the recess depth and conductivity of the electrolyte satisfy a specific relationship, allowing active material particles to embed within the recesses and maintain effective contact, thereby preventing fall-off
Implementation Method 2
the electrolyte has a conductivity σ in Siemens/meter, and numerically, σ and h1 satisfy the following relationship
Implementation Method 3
Lithium-ion batteries with high power performance have competitive advantages in vehicle acceleration and energy recovery. However, during long-term charge-discharge cycling of lithium-ion batteries, positive and negative electrode active materials gradually fall off current collectors, seriously affecting the service life and power performance of cells
Data Source
AI summary
A secondary battery, including a positive electrode, a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, and an electrolyte are provided. In some embodiments, the positive electrode includes a positive electrode current collector having two main surfaces, the negative electrode includes a negative electrode current collector having two main surfaces, and at least one of the positive electrode current collector and the negative electrode current collector includes at least one recess structure extending from at least one main surface into interior of the current collector, where the recess structure has a recess depth h1 in microns, the electrolyte has a conductivity σ in Siemens/meter, and numerically, σ and h1 satisfy the following relationship: 8tanhh1+0.2h1≤σ≤10tanh(h1)2+2+0.1h1. This application further provides a battery module including the foregoing secondary battery, a battery pack, and an electric apparatus.