Silicon Anode Paste with CNT Network for Cycle-Life Retention
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Solution Overview
Problem
Conventional silicon-containing negative electrodes in lithium-ion batteries suffer from a short operational life due to volume expansion during charge-discharge cycles, leading to structural integrity loss and reduced capacity, which limits their widespread application.
Innovation Solution
The method involves producing an anode slurry with a high concentration of silicon or silicon oxide phases and bundled single-walled or double-walled carbon nanotubes, where a substantial fraction of these nanotubes have lengths greater than 10 μm and less than 5 μm, ensuring mechanical and electrical integrity and conductivity through a network of carbon nanotubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-containing anode material is used to achieve high specific capacity, then the specific capacity increases, but the operational life decreases due to volume expansion and structural degradation
Solution Approach 1:
The patent creates a porous structure within the anode material in advance, allowing formed lithium silicide to fill these pores. This accommodates the 400% volume expansion of silicon particles during lithiation without causing structural failure, thereby preserving anode integrity over multiple charge-discharge cycles while maintaining high specific capacity
Solution Approach 2:
The patent uses a silicon-carbon composite as the active material of the negative electrode. The carbon component provides structural stability and conductivity, while the silicon component delivers high specific capacity. This composite structure reduces the relative volume change during lithiation compared to pure silicon, enabling both high capacity and long cycle life
2Stability of the object's composition
If silicon-carbon composite is used to reduce volume change during lithiation, then structural integrity is improved, but specific capacity decreases due to linear dependence on volume change
Solution Approach 1:
The patent introduces a porous structure that allows the silicon particles to expand into the pores during lithiation. This internal expansion space enables the silicon-carbon composite to achieve both structural integrity and high specific capacity by accommodating the volume change without compromising the overall anode structure
Solution Approach 2:
The patent changes the physical structure parameter by introducing porosity to the anode material. This allows the material to dynamically adjust its volume during charge-discharge cycles, enabling the silicon-carbon composite to maintain both structural stability and high specific capacity that would otherwise be mutually exclusive
3Duration of action of moving object
If porous structure is created in advance to accommodate volume expansion, then operational life is improved, but manufacturing complexity increases
Solution Approach 1:
The patent creates the porous structure in advance during the anode manufacturing process, before the battery is assembled and before any charge-discharge cycles occur. This preliminary creation of porosity simplifies the overall process by avoiding the need for complex post-processing or in-situ pore formation mechanisms
Solution Approach 2:
The patent employs a porous structure that can be integrated into the existing anode manufacturing workflow. The porous anode material is formed as a single integrated component during standard manufacturing processes, avoiding the need for separate porous substrate fabrication and material deposition steps that would increase complexity
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 anode maintains an initial specific capacity of over 500 mA·h/g and retains more than 80% of its capacity for at least 500 charge-discharge cycles, while simplifying the manufacturing process and maintaining conductivity and structural integrity.
Implementation Method 1
comprising more than 0.1 wt. % and less than 20 wt. % of carbon nanotubes, wherein the mode of length distribution of the number of bundles of carbon nanotubes is less than 5 μm
Data Source
AI summary
The invention relates to electrotechnical industry, more particularly to lithium-ion batteries, and even more particularly to lithium-ion batteries with silicon-containing negative electrode (anode). The invention provides a method for producing an anode slurry (paste), an anode slurry (paste), a method for producing an anode for a lithium-ion battery, an anode for a lithium-ion battery, and a lithium-ion battery with a high initial specific capacity and a long cycle life with a large number of charge-discharge cycles over which the battery retains at least 80% of its initial capacity. This result becomes possible due to the presence in the anode material of bundles of single-walled and/or double-walled carbon nanotubes having a length of less than 5 μm, together with bundles of single-walled and/or double-walled carbon nanotubes having a diameter of more than 500 nm and a length of more than 10 μm.