Carbon-Coated Silicon Anode Material for Conductive Path Stability
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Solution Overview
Problem
Silicon-based negative electrode active materials in lithium secondary batteries face issues such as volume expansion during charging, leading to disconnection of conductive paths and generation of gases, which deteriorate battery performance and stability.
Innovation Solution
A silicon-based active material coated with a carbon layer having a specific Raman peak intensity ratio (ID/IG of 0.1 to 1.2) is used, along with controlled chemical deposition and specific surface area adjustments, to form a protective layer that prevents solvent reactions and enhances electric conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon-based compound is used as a negative electrode active material to increase capacity, then the discharge capacity is improved, but the volume rapidly expands during charging causing disconnection of conductive paths and deterioration of battery characteristics
Solution Approach 1:
A carbon coating layer with a specific Raman ID/IG ratio of 0.1 to 1.2 is applied as a thin film on the silicon-based active material surface. This carbon layer acts as a flexible protective shell that accommodates volume expansion during charging while maintaining conductive path integrity, preventing disconnection and preserving battery characteristics.
Solution Approach 2:
The invention creates a composite structure combining silicon-based active material with a carbon coating layer. The silicon core provides high discharge capacity while the carbon outer layer provides structural stability and conductivity, creating a composite material that exhibits both high capacity and reliable battery characteristics.
2Reliability
If measures are taken to suppress volume expansion by coating the active material layer with a thin film, then the conductive path disconnection is prevented, but the battery performance deteriorates
Solution Approach 1:
The invention changes the critical parameter of the carbon coating layer's Raman ID/IG ratio to a specific range of 0.1 to 1.2. This parameter optimization ensures the carbon layer has appropriate structural properties that maintain conductivity while accommodating volume expansion, thus preventing conductive path disconnection without sacrificing battery performance.
3Duration of action of stationary object
If the electrode resistance is lowered to secure service life stability, then the service life is improved, but gases are generated due to reaction with solvent during slurry preparation causing non-uniform electrode coating
Solution Approach 1:
The carbon coating layer serves as an intermediary between the silicon-based active material and the slurry solvent. It prevents direct reaction between silicon and solvent during slurry preparation, eliminating gas generation and ensuring uniform electrode coating, while also providing long-term service life stability.
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 carbon coating layer reduces stress on the silicon-based material, prevents gas generation, and improves electrode stability and conductivity, thereby enhancing the service life and capacity performance of the battery.
Implementation Method 1
the carbon coating layer reduces stress on the silicon-based material
Implementation Method 2
prevents solvent reactions and enhances electric conductivity
Implementation Method 3
enhances electric conductivity
Data Source
AI summary
A negative electrode active material, a method for preparing the same, a negative electrode composition and a negative electrode including the same, and a lithium secondary battery including the negative electrode are provided. The negative electrode active material comprises a silicon-based active material; and a carbon coating layer covering at least a portion of an outer surface of the silicon-based active material, the carbon coating layer comprising carbon having a Raman peak intensity ratio ID/IG of 0.1 to 1.2, the silicon-based active material including Si and optionally SiOx (0<x<2), and Si being comprised in an amount of 70 parts by weight or more based on 100 parts by weight of the silicon-based active material.