Silicon Oxide Negative Electrode Composition for Lithium Secondary Batteries
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in maximizing energy density and service life due to the use of silicon-based negative electrode materials, which experience significant volume expansion during charging and discharging, leading to degradation and reduced performance.
Innovation Solution
A negative electrode composition comprising silicon oxide with Si nanograins of specific particle size, combined with a linear conductive material and a PAM-based aqueous binder, is used to stabilize the electrode structure and enhance conductivity, thereby improving energy density and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-carbon-based negative electrode materials (silicon, tin, oxides) are used to increase capacity, then energy density is improved, but irreversible capacity loss increases due to low initial efficiency
Solution Approach 1:
The patent uses silicon oxide as a composite negative electrode material that combines the high capacity benefits of silicon-based materials with the stability of oxide structures. This composite approach achieves high energy density while reducing irreversible capacity loss compared to pure silicon or tin materials.
Solution Approach 2:
The patent changes the chemical composition parameter from pure silicon or tin to silicon oxide, which has different electrochemical properties. This parameter change reduces the irreversible capacity loss while maintaining high capacity, as silicon oxide exhibits better initial efficiency than non-carbon-based materials like pure silicon.
2Quantity of substance
If electrode loading is increased to improve energy density, then energy density is improved, but electrode resistance and cell resistance increase, reducing output and charging performance
Solution Approach 1:
The patent changes the material composition parameter to silicon oxide, which has different electrical and structural properties compared to traditional graphite or pure silicon. This parameter change allows for optimized electrode loading that maintains both high energy density and acceptable resistance levels, improving output performance.
3Quantity of substance
If silicon-based negative electrode materials are used to increase capacity, then energy density is improved, but volume expansion occurs during charging and discharging, leading to degradation
Solution Approach 1:
The patent employs silicon oxide as a composite material that combines the high capacity characteristics of silicon-based materials with the structural stability of oxide compounds. This composite structure mitigates the severe volume expansion problem of pure silicon while maintaining high capacity, thereby improving electrode structure stability during charging and discharging cycles.
Solution Approach 2:
The patent changes the chemical composition from pure silicon to silicon oxide, which has a more stable crystal structure and lower volume expansion ratio. This parameter change fundamentally addresses the stability issue while preserving the high capacity benefits of silicon-based materials.
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 composition effectively stabilizes the electrode structure, reducing degradation and enhancing the energy density and service life of lithium secondary batteries by uniformly diffusing Li ions and maintaining the electrode's integrity during charging and discharging.
Implementation Method 1
uniformly diffusing Li ions and maintaining the electrode's integrity during charging and discharging
Data Source
Figure 1~2
AI summary
The present invention relates to a negative electrode composition, a negative electrode for a lithium secondary battery comprising the negative electrode composition, and a lithium secondary battery comprising same, whereby, by using a negative electrode active material including silicon oxide in which Si nanocrystals having an average particle diameter (D50) of 0.1 nm or more and 5 nm or less are included, in an appropriate composition combination with a negative electrode conductive material and a negative electrode aqueous binder, the energy density of a lithium secondary battery is enhanced, and by lowering the degree of degradation when driving the lithium secondary battery, the life characteristics can be further improved.