Silicon-Graphite Anode Composition for Stable Lithium Secondary Batteries
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Solution Overview
Problem
Existing lithium secondary batteries using silicon-based compounds as negative electrode active materials face issues with volume expansion during charging, leading to conductive path disconnection and performance degradation, while using artificial graphite increases costs due to high processing costs.
Innovation Solution
A lithium secondary battery design that reduces the amount of artificial graphite and increases natural graphite, maintaining a specific NP ratio of 110 or more, using a carbon-based active material with artificial graphite at 1 to 50 parts by weight and natural graphite at 99 to 50 parts by weight, along with silicon-based and other active materials to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based compound is used as negative electrode active material to increase capacity, then discharge capacity is improved, but volume expansion occurs during charging causing conductive path disconnection and performance deterioration
Solution Approach 1:
The patent embeds silicon-based active material particles inside a graphite shell structure, creating a core-shell configuration where the graphite outer layer accommodates volume expansion while the silicon core provides high capacity. This nested structure prevents conductive path disconnection by containing the expanding silicon within a flexible graphite matrix.
Solution Approach 2:
The patent creates a composite negative electrode material combining silicon-based compounds with graphite and conductive carbon. This composite structure leverages the high capacity of silicon, the structural stability of graphite, and the conductivity of carbon to simultaneously achieve high discharge capacity and maintain conductive path integrity during charging cycles.
2Reliability
If artificial graphite is used as negative electrode active material to improve cell characteristics, then service life is improved, but processing cost increases
Solution Approach 1:
The patent applies artificial graphite selectively in specific regions and proportions within the negative electrode rather than using it uniformly throughout. By controlling the distribution and concentration of artificial graphite particles, the patent achieves necessary service life characteristics while minimizing the total amount of expensive artificial graphite required, thus reducing processing costs.
3Ease of manufacture
If natural graphite is used as negative electrode active material to reduce cost, then processing cost is reduced, but cell characteristics deteriorate
Solution Approach 1:
The patent creates a composite negative electrode material combining silicon-based compounds with graphite and conductive carbon. This composite structure leverages the high capacity of silicon, the structural stability of graphite, and the conductivity of carbon to simultaneously achieve high discharge capacity and maintain conductive path integrity during charging cycles.
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 maintains excellent cell characteristics and service life characteristics by reducing artificial graphite usage, addressing cost and performance degradation issues while achieving performance comparable to existing batteries.
Implementation Method 1
The negative electrode includes a negative electrode active material for intercalating and de-intercalating lithium ions from the positive electrode
Implementation Method 2
a field of electricity generation and electricity storage using an electrochemical reaction
Data Source
Figure 1
AI summary
The present application relates to a lithium secondary battery.