Positive Electrode Tab Coating for Lower Lithium Plating Risk
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Solution Overview
Problem
Existing electrochemical devices, such as lithium-ion batteries, face challenges in enhancing energy density and safety performance due to the limitations of conventional insulating layers, which do not effectively utilize their capacity and can lead to lithium plating and excessive polarization.
Innovation Solution
A protective coating is applied to the positive electrode current collector, comprising a first active material like ferrous lithium phosphate and a conductive agent, which provides a certain gram capacity and resistance, thereby increasing energy density and reducing the risk of lithium plating by allowing normal charge and discharge processes without excessive polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating layer is applied to the cutting position of the electrode plate to prevent burrs from piercing the separator, then safety performance is improved, but the gram capacity is not utilized and energy density increases are limited
Solution Approach 1:
The protective coating is designed to simultaneously perform multiple functions: it provides electrical insulation to prevent short circuits between the current collector and separator, prevents mechanical piercing by cutting burrs, and contributes electrochemical capacity through active materials. This multi-functional design resolves the contradiction by making the protective layer productive rather than parasitic.
Solution Approach 2:
The protective coating employs composite materials containing active material particles (such as aluminum oxide, aluminum hydroxide, or勃姆石), conductive agents (such as carbon black or carbon nanotubes), and binders. This composite structure provides both the protective functions (insulation and mechanical protection) and electrochemical functionality, enabling the coating to contribute to energy density while maintaining safety.
2Quantity of substance
If a protective coating with active material is used to increase energy density, then gram capacity is utilized, but excessive polarization may occur leading to lithium plating
Solution Approach 1:
The protective coating is applied specifically at the cutting positions and tab portions of the electrode plate where polarization and lithium plating risks are highest. By localizing the coating to these critical areas rather than applying it uniformly across the entire electrode, the design addresses polarization issues where they occur most severely while minimizing the impact on overall energy density.
Solution Approach 2:
The coating weight per unit area is precisely controlled within the range of 0.026-0.182 mg/mm², and the active material content is optimized at 85-99% by mass. These parameter optimizations ensure the coating provides sufficient protection and capacity contribution while maintaining appropriate electrical conductivity to prevent excessive polarization and lithium plating.
3Quantity of substance
If the coating weight per unit area of the protective coating is increased to provide more capacity, then energy density improves, but electrical conductivity decreases and lithium plating risk increases
Solution Approach 1:
The coating weight per unit area is optimized within a specific range (0.026-0.182 mg/mm²) and the active material content is controlled at 85-99% by mass. These parameter optimizations ensure the coating provides sufficient protective function and capacity contribution while maintaining appropriate electrical conductivity to prevent excessive polarization and lithium plating.
Solution Approach 2:
The protective coating employs composite materials containing active material particles (such as aluminum oxide, aluminum hydroxide, or勃姆石), conductive agents (such as carbon black or carbon nanotubes), and binders. This composite structure provides both the protective functions (insulation and mechanical protection) and electrochemical functionality, enabling the coating to contribute to energy density while maintaining safety.
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
The protective coating enhances the energy density and safety performance of electrochemical devices by providing a lithium ion path and reducing the risk of lithium plating, while maintaining appropriate electrical conductivity and bonding properties.
Implementation Method 1
the cutting position is coated with an insulating layer, so as to achieve the effects of insulating
Implementation Method 2
the protective coating includes a first active material... providing a lithium ion path
Data Source
AI summary
An electrochemical device includes a positive electrode, the positive electrode including a positive electrode current collector, a protective coating disposed on a surface of one side of the positive electrode current collector close to a tab portion, and a positive electrode active material layer disposed on a surface of at least one side of the positive electrode current collector. The protective coating includes a first active material, and the positive electrode active material layer includes a second active material. According to embodiments of this application, by disposing the protective coating on the positive electrode current collector, lithium plating at the negative electrode of the electrochemical device is alleviated while ensuring the safety performance of the electrochemical device.