Silicon-Carbon Negative Electrode Orientation for Fast-Charging Batteries
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Solution Overview
Problem
Conventional lithium secondary batteries face limitations in energy density and rapid charging performance due to the use of graphite as a negative electrode active material, which results in slow lithium insertion reactions and high charging times, especially in applications like electric vehicles.
Innovation Solution
A negative electrode comprising a carbon-based and silicon-based active material blend, with a controlled orientation index and particle size distribution, applied using a magnetic field to enhance adhesion and ion migration, is used in conjunction with a specific positive electrode material and electrolyte composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode active material is used to increase capacity, then energy density is improved, but volume expansion and lifespan are worsened
Solution Approach 1:
The patent uses a composite negative electrode active material consisting of silicon particles (0.1-10 wt%), carbon particles (5-20 wt%), and conductive polymer particles (1-5 wt%). This composite structure combines the high capacity of silicon with the stability of carbon and conductive polymer, achieving both high energy density and improved lifespan by preventing silicon volume expansion and maintaining electrical conductivity.
2Stability of the object's composition
If graphite is used as negative electrode active material, then structural stability is improved, but lithium insertion reaction speed and charging time are worsened
Solution Approach 1:
The patent creates local quality variations by distributing different materials throughout the negative electrode active material. Silicon particles provide high-capacity regions for rapid lithium insertion, while carbon and conductive polymer particles provide stable structural regions and conductive pathways. This local differentiation enables both fast charging and structural stability.
Solution Approach 2:
The patent changes the compositional parameters of the negative electrode active material by incorporating silicon (0.1-10 wt%), carbon (5-20 wt%), and conductive polymer (1-5 wt%). This parameter change transforms the material properties, enabling faster lithium insertion reactions while maintaining structural stability through the synergistic effects of the composite components.
3Quantity of substance
If silicon content is increased to improve capacity, then charge and discharge capacity is improved, but adhesion and electrical conductivity are worsened
Solution Approach 1:
The patent introduces carbon particles and conductive polymer particles as intermediary materials between silicon particles and the current collector. These intermediaries improve adhesion by providing bonding interfaces and enhance electrical conductivity by creating conductive networks. This allows higher silicon content (0.1-10 wt%) to be used while maintaining adequate adhesion and conductivity.
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 electrode achieves high charge and discharge capacity, improved lifespan, and rapid charging capabilities, enabling lithium secondary batteries to be charged in a short time even at standard rates, enhancing their suitability for electric vehicles.
Implementation Method 1
applying magnetic field to the applied negative electrode slurry
Data Source
Figure 1(a)~1(b)
AI summary
A negative electrode includes a carbon-based negative electrode active material and a silicon-based negative electrode active material in a predetermined content ratio, and by controlling the orientation index (0.1) of the carbon-based negative electrode active material of the negative electrode active layer including them to a certain range, it has the characteristics of high charge and discharge capacity as well as excellent lifespan characteristics. Moreover, the lithium secondary battery comprising the negative electrode has the advantage of having excellent output characteristics and can be charged in a short time even at a 1C-rate.