Amorphous Silicon Oxide Negative Electrode for Lithium Battery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges due to volume expansion of the negative active material during charge and discharge, leading to surface cracks and deterioration of cycle-life characteristics.
Innovation Solution
A lithium secondary battery design featuring a negative electrode with an amorphous silicon oxide active material layer coated with a thin carbon layer and an SEI layer with specific surface protrusions, which prevents volume expansion and improves cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional negative active materials are used, then the battery can be manufactured with standard materials, but volume expansion occurs during charge and discharge leading to cracks and poor cycle-life
Solution Approach 1:
The patent changes the chemical composition parameters of the negative active material by incorporating silicon oxide (SiOx) with specific oxygen content (x=0.9-1.2) and controlling the amorphous phase ratio to 70-90%. This compositional parameter change enables the material to achieve both high capacity and volume stability during charge-discharge cycles, resolving the contradiction between reliability and compositional stability.
Solution Approach 2:
The patent creates a composite negative active material consisting of silicon oxide particles coated with a carbon layer, forming a SiOx@C composite structure. The carbon coating layer prevents direct contact between silicon oxide and electrolyte, suppresses volume expansion, and maintains structural integrity during cycling, thereby improving cycle-life while maintaining volume stability.
2Quantity of substance
If the negative active material undergoes volume expansion, then lithium intercalation capacity is improved, but cracks form on the surface leading to deterioration of cycle-life
Solution Approach 1:
The patent optimizes the oxygen content parameter in silicon oxide (controlling x in SiOx to be 0.9-1.2) and the amorphous phase ratio (70-90%), which allows the material to achieve optimal lithium intercalation capacity while suppressing excessive volume expansion that would cause cracking and cycle-life deterioration.
Solution Approach 2:
The carbon coating layer acts as an intermediary between the silicon oxide active material and the electrolyte. It allows lithium ion transport while preventing direct electrolyte contact with silicon oxide, suppressing harmful side reactions and volume expansion-induced cracking, thereby maintaining both capacity and cycle-life.
3Reliability
If a carbon layer is coated on amorphous silicon oxide, then volume expansion is prevented and cycle-life is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies a thin carbon film coating on the silicon oxide particles. This thin film structure provides protective functions (preventing volume expansion and electrolyte contact) while adding minimal structural complexity and maintaining ease of manufacturing through established coating techniques.
4Reliability
If an SEI layer is formed on the negative electrode, then it protects the active material, but surface protrusions may form affecting performance
Solution Approach 1:
The carbon coating layer serves as an intermediary that controls SEI layer formation. It mediates between the silicon oxide active material and the electrolyte, enabling formation of a uniform SEI layer with controlled surface protrusions (5-300 nm) that provide protection while maintaining surface uniformity and preventing excessive roughness that would harm performance.
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 battery design significantly reduces crack occurrence and enhances cycle-life characteristics by maintaining a stable SEI layer and preventing volume expansion, resulting in improved charge and discharge efficiency and capacity retention.
Implementation Method 1
a positive electrode, a negative electrode, and an electrolyte. The negative electrode includes a current collector, an active material layer on the current collector
Implementation Method 2
Batteries transform chemical energy (generated from an electrochemical redox reaction of a chemical material in the battery) into electrical energy
Implementation Method 3
The active material is preferably formed of the amorphous silicon oxide, and a carbon layer is coated on at least a part of the amorphous silicon oxide. The lithium secondary battery substantially prevents expansion of the negative active material during charge and discharge
Implementation Method 4
an SEI layer on the active material layer. The SEI layer preferably comprises about 70 area% to about 99.9 area% of protrusion parts with a size ranging from about 5 nm to 300 nm on the surface
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
A lithium secondary battery includes a positive electrode, a negative electrode, and an electrolyte. The negative electrode (312) includes a current collector (210), an active material (221) layer (220) on the current collector generally including an amorphous silicon oxide represented by SiOx (0.95<x<1.7), preferably partially coated with a carbon layer, and an SEI layer (230) on the active material layer which has at most 70 area% of protrusion parts having a size of about 5 nm to about 300 nm during the charging of the battery.