Silicon Negative Electrode Coating for Lithium Battery Capacity Retention
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Solution Overview
Problem
Lithium secondary batteries face limitations in capacity retention and lifespan due to volumetric swelling or shrinkage of non-carbonaceous negative active materials during charging and discharging, which affects their performance and efficiency.
Innovation Solution
A negative active material comprising nano-size silicon-based primary particles with a crystalline structure and an amorphous carbonaceous coating layer, produced through a milling process with an emulsifier, which enhances electric conductivity and reduces surface oxidation, thereby improving capacity and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-carbonaceous materials are used as negative active material, then capacity density is improved (10 times greater than graphite), but volumetric swelling or shrinkage during charging and discharging leads to decreased capacity retention ratios, charging/discharging efficiency, and lifespan characteristics
Solution Approach 1:
The negative active material is divided into nano-sized particles (1-100 nm diameter) to segment the bulk material into smaller units. This segmentation reduces the volumetric swelling or shrinkage effect during lithium ion intercalation and deintercalation, thereby improving capacity retention ratios and lifespan characteristics while maintaining high capacity density
Solution Approach 2:
The patent uses non-carbonaceous materials (such as metal oxides, metal sulfides, or alloy materials) that are not traditionally used as negative active materials. These composite materials provide higher capacity density compared to conventional graphite, while the nano-sizing mitigates their volumetric expansion issues
2Quantity of substance
If non-carbonaceous materials are used as negative active material, then capacity density is improved, but charging/discharging efficiency decreases due to volumetric swelling or shrinkage
Solution Approach 1:
By dividing the non-carbonaceous material into nano-sized particles, the patent reduces the volumetric swelling or shrinkage during charging and discharging cycles. This segmentation enables faster and more efficient lithium ion intercalation and deintercalation, thereby improving charging/discharging efficiency while maintaining high capacity density
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 silicon-based negative active material achieves a high capacity of 3000 mAh/g or more and improved cycle characteristics, with reduced surface damage and oxidation, leading to enhanced performance and efficiency in lithium batteries.
Implementation Method 1
the amorphous carbonaceous coating layer may include a carbonized material, where the carbonized material may be made from an organic material selected from sucrose, glucose, galactose, fructose, lactose, starch, mannose, ribose, aldohexose, ketohexose, and a combination thereof
Implementation Method 2
Lithium secondary batteries produce electrical energy by oxidation and reduction reactions that occur when lithium ions are intercalated to or deintercalated from a positive electrode and a negative electrode
Data Source
AI summary
In an aspect, a negative active material, a method of preparing the negative active material, and a lithium battery including the negative active material are provided. The method of preparing the negative active material may increase pulverizing efficiency in pulverizing a silicon-based bulky particle into a nano-size silicon-based primary particle and decrease a capacity loss of the obtained negative active material. The nano-size negative active material has excellent crystalline characteristics, high capacity, and high initial efficiency, due to a decrease in surface oxidation and surface damage.