Silicon Oxide Negative Electrode Active Material for Li-Ion Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium ion secondary batteries face challenges in achieving higher initial discharge capacity and improved high-temperature storage characteristics, as existing negative electrode active materials struggle to efficiently store and desorb lithium ions and maintain stability during volume changes.
Innovation Solution
A negative electrode active material is developed, comprising silicon oxide particles with carbon coating, where the X-ray diffraction peak intensity ratio (PSi/PSiO2) is between 1.0 and 2.6, and a specific surface area calculated from moisture adsorption is 6.5 m2/g or less, along with a carbon content of 0.1% to 10% by mass, to enhance conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon oxide particles with higher theoretical capacity are used to improve battery capacity, then the initial discharge capacity is improved, but the volume expansion during lithium absorption and desorption causes poor cycle stability
Solution Approach 1:
A carbon film coating is applied to the surface of silicon oxide particles. This carbon shell accommodates the volume expansion and contraction of silicon oxide during lithium absorption and desorption, preventing particle fracture and maintaining structural integrity over multiple cycles, thus improving cycle stability while preserving high capacity
Solution Approach 2:
The invention uses composite silicon oxide particles consisting of silicon oxide core material combined with a carbon outer layer. This composite structure combines the high capacity advantage of silicon oxide with the structural stability and conductivity benefits of carbon, resolving the contradiction between capacity and cycle life
2Reliability
If the surface of silicon oxide particles is coated with carbon to improve conductivity and stability, then cycle characteristics are improved, but the specific surface area increases leading to excessive moisture adsorption
Solution Approach 1:
The invention optimizes the carbon coating thickness and composition to achieve a balance: sufficient carbon coverage to provide conductivity and structural stability for good cycle characteristics, but controlled thickness to limit specific surface area and moisture adsorption to 8.5 cm³/g or less
Solution Approach 2:
The carbon coating is applied selectively to specific regions of the silicon oxide particle surface where it provides the most benefit for conductivity and structural support, rather than uniform thick coating, thereby reducing overall surface area and moisture adsorption while maintaining cycle stability
3Reliability
If the specific surface area is reduced to decrease moisture adsorption, then high-temperature storage characteristics are improved, but the contact area with electrolyte decreases reducing charge-discharge efficiency
Solution Approach 1:
The invention optimizes particle size and carbon coating thickness to achieve an optimal specific surface area range that limits moisture adsorption to improve high-temperature storage, while maintaining sufficient electrolyte contact area through appropriate particle morphology and controlled coating thickness to preserve charge-discharge efficiency
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
This configuration significantly improves the initial discharge capacity and high-temperature storage characteristics of lithium ion secondary batteries by optimizing the silicon oxide particle structure and carbon content, leading to enhanced charge-discharge efficiency and cycle stability.
Implementation Method 1
fusing carbon to at least a part of the surface thereof for imparting conductivity
Implementation Method 2
absorption and desorption of lithium
Implementation Method 3
a ratio (PSi/PSiO2) of an intensity of an X-ray diffraction peak at 2θ of from 27° to 29°, which is derived from Si, to an intensity of an X-ray diffraction peak at 2θ of from 20° to 25°, which is derived from SiO2
Implementation Method 4
a specific surface area calculated from moisture adsorption at 298 K is 6.5 m2/g or less
Data Source
AI summary
A negative electrode active material for a lithium ion secondary battery, the negative electrode active material includes silicon oxide particles, each of which has carbon on at least a portion of its surface, in which: a ratio (PSi/PSiO2) of an intensity of an X-ray diffraction peak at 2θ of from 27° to 29°, which is derived from Si, to an intensity of an X-ray diffraction peak at 2θ of from 20° to 25°, which is derived from SiO2, is within a range of from 1.0 to 2.6, when CuKα radiation having a wavelength of 0.15406 nm is used as a radiation source; and a specific surface area calculated from moisture adsorption at 298 K is 6.5 m2/g or less.