Gradient Silicon-Graphite Anode for Fast-Charging Li-Ion Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high electrochemical properties and mechanical stability, particularly in maintaining capacity and preventing excessive volume expansion during charging and discharging, which affects their lifespan and rapid charging performance.
Innovation Solution
An anode for lithium secondary batteries is designed with an active material layer comprising artificial graphite and silicon-based materials, where the silicon-based active material has a specific particle size distribution and doping elements, and is structured with varying content in different regions to control expansion and enhance porosity, thereby improving stability and diffusion rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase capacity, then battery capacity is improved, but volume expansion occurs during charging and discharging
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of silicon-based active material within the anode active material layer. The content of silicon-based active material varies from the bottom surface (adjacent to current collector) to the top surface, with higher concentration at the bottom and lower concentration at the top. This gradient structure allows the anode to accommodate volume expansion locally where silicon is present while maintaining overall structural integrity, thus resolving the contradiction between increasing capacity and controlling volume expansion.
Solution Approach 2:
The patent uses composite materials by combining silicon-based active material with artificial graphite-based active material in a gradient structure. The artificial graphite provides structural stability and accommodates volume changes, while the silicon-based material provides high capacity. The gradient composition optimizes the balance between capacity enhancement and volume stability, resolving the technical contradiction.
2Productivity
If silicon-based active material content is increased, then rapid charging performance is improved, but structural stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of silicon-based active material within the anode active material layer. The content of silicon-based active material varies from the bottom surface (adjacent to current collector) to the top surface, with higher concentration at the bottom and lower concentration at the top. This gradient structure allows the anode to accommodate volume expansion locally where silicon is present while maintaining overall structural integrity, thus resolving the contradiction between increasing capacity and controlling volume expansion.
Solution Approach 2:
The patent uses composite materials by combining silicon-based active material with artificial graphite-based active material in a gradient structure. The artificial graphite provides structural stability and accommodates volume changes, while the silicon-based material provides high capacity. The gradient composition optimizes the balance between capacity enhancement and volume stability, resolving the technical contradiction.
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 anode design enhances the battery's electrochemical properties, including improved rapid charging performance and extended lifespan by controlling volume expansion and maintaining structural integrity during repeated charge-discharge cycles.
Implementation Method 1
a silicon-based active material and a carbon-based active material may be used together as an anode active material
Implementation Method 2
A content of the silicon-based active material based on a total weight of the anode active material included in the second region is greater than a content of the silicon-based active material based on a total weight of the anode active material included in the first region
Implementation Method 3
The anode active material layer includes an anode active material including an artificial graphite-based active material and a silicon-based active material
Data Source
AI summary
An anode for a lithium secondary battery includes an anode current collector, and an anode active material layer formed on at least one surface of the anode current collector. The anode active material layer includes a first region adjacent to the anode current collector and a second region spaced apart from the anode current collector in a thickness direction with the first region interposed therebetween. The anode active material layer includes an anode active material including an artificial graphite-based active material and a silicon-based active material having a minimum particle diameter (Dmin) in a range from 1 μm to 5 μm. A content of the silicon-based active material based on a total weight of the anode active material included in the second region is greater than a content of the silicon-based active material based on a total weight of the anode active material included in the first region.