Carbon-Shell Negative Electrode Material for Roll-Pressed Li Batteries
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in maintaining structural integrity of the negative electrode active material during roll pressing, which affects the production of high-density electrode plates and overall battery performance.
Innovation Solution
A negative electrode active material comprising a core of amorphous carbon surrounded by multiple shells of crystalline and amorphous carbon, with a specific D/G ratio, is developed to enhance rollability and electrical conductivity, preventing structural collapse during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional negative electrode active materials are used, then the electrode structure maintains simplicity, but structural collapse occurs during roll pressing
Solution Approach 1:
The negative electrode active material is divided into core and shell portions, where the core contains the active material and the shell contains conductive carbon material. This segmentation prevents structural collapse during roll pressing while maintaining electrical conductivity, resolving the contradiction between structural integrity and material simplicity.
Solution Approach 2:
The patent creates a composite structure combining the negative electrode active material core with a conductive carbon shell. This composite material approach enhances structural stability during processing while improving electrical conductivity, addressing both the structural integrity and complexity concerns.
2Quantity of substance
If the negative electrode active material undergoes roll pressing to create high-density electrode plates, then electrode density improves, but structural collapse occurs
Solution Approach 1:
The conductive carbon shell is formed beforehand to cushion and protect the negative electrode active material core during roll pressing. This pre-formed protective layer prevents structural collapse while enabling high-density electrode plate production, resolving the contradiction between density and strength.
3Reliability
If the negative electrode active material is designed with enhanced conductivity, then electrical performance improves, but manufacturing complexity increases
Solution Approach 1:
The conductive carbon shell is designed as a thin film structure that provides enhanced electrical conductivity while maintaining manufacturing feasibility. This thin shell approach improves electrical performance without excessively increasing manufacturing complexity, resolving the contradiction between reliability and ease of manufacture.
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 solution results in a high-density negative electrode with improved capacity, efficiency, and quick charging performance, maintaining the integrity of the electrode structure and facilitating efficient lithium ion movement.
Implementation Method 1
an active material that allows intercalation and deintercalation of lithium ions
Implementation Method 2
The batteries produce electrical energy from redox reactions that take place as lithium ions are intercalated into or deintercalated from the positive electrode and the negative electrode
Data Source
AI summary
A negative electrode active material includes a core containing a first amorphous carbon and a shell on the core. The shell includes a first shell on the core, with the first shell including a crystalline carbon. The shell also includes a second shell on the first shell, with the second shell including a second amorphous carbon. A ratio of a D/G value of the core to a DIG value of the shell including the first shell and the second shell is about 1.4 to about 15.