Negative Electrode Composition for High-Rate Silicon Batteries
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with high-rate charge and discharge characteristics due to the contraction and expansion of silicon-based negative active materials, leading to increased charge transfer resistance and lithium ion trapping, which affects the battery's energy density and cycle life.
Innovation Solution
A negative electrode composition including lithium titanium oxide with a specific aspect ratio, needle-type carbon-based materials, and a silicon-based or carbon-based active material, forming a conductive network to enhance ion and electrical conductivity, thereby reducing charge transfer resistance and improving high-rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase energy density, then battery capacity is improved, but charge transfer resistance increases due to contraction and expansion during charging and discharging
Solution Approach 1:
The patent changes the physical and chemical parameters of the negative electrode by incorporating lithium titanium oxide with specific aspect ratios (10:1 to 2:1) and controlling silicon content (5-50 wt%). This modifies the electrode's structural stability and electrical properties, allowing high capacity while reducing charge transfer resistance through optimized material composition and morphology.
Solution Approach 2:
The patent creates a composite negative electrode material combining lithium titanium oxide, silicon-based active material, and needle-type carbon-based material. This composite structure leverages the high capacity of silicon, the stability of lithium titanium oxide, and the conductivity of carbon materials to simultaneously achieve high energy density and low charge transfer resistance.
2Quantity of substance
If silicon-based active material is used to increase energy density, then battery capacity is improved, but lithium ion trapping occurs due to volume expansion
Solution Approach 1:
The patent employs needle-type carbon-based material (carbon nanotubes or carbon nano fibers) as a flexible conductive network that can accommodate the volume expansion of silicon during charging and discharging. This flexible carbon matrix prevents lithium ion trapping by maintaining continuous contact and providing stable ion transport pathways despite silicon's volume changes.
Solution Approach 2:
The composite structure of silicon-based active material embedded in a matrix of lithium titanium oxide and needle-type carbon-based material prevents lithium ion trapping. The lithium titanium oxide provides structural stability while the carbon network ensures continuous electrical contact, allowing lithium ions to be released efficiently even when silicon expands.
3Ease of manufacture
If conventional negative electrode materials are used, then manufacturing simplicity is maintained, but high-rate charge and discharge characteristics are poor
Solution Approach 1:
The patent optimizes the aspect ratio of lithium titanium oxide to a specific range (10:1 to 2:1) and controls the mixing ratios of components (silicon: 5-50 wt%, lithium titanium oxide: 1-50 wt%, needle-type carbon-based material: 1-50 wt%). These parameter changes enhance ion and electrical conductivity, enabling excellent high-rate charge and discharge characteristics while maintaining compatibility with conventional manufacturing processes.
Solution Approach 2:
The patent develops a composite negative electrode material combining lithium titanium oxide, silicon-based active material, and needle-type carbon-based material. This composite structure provides excellent ion conductivity and electrical conductivity, enabling high-rate charge and discharge performance while using standard battery manufacturing techniques.
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 proposed negative electrode exhibits excellent ion conductivity and high-rate charge and discharge characteristics, minimizing charge transfer resistance and maintaining specific capacity and cycle-life characteristics.
Implementation Method 1
forming a conductive network to enhance ion and electrical conductivity
Implementation Method 2
an active material being capable of intercalating and deintercalating lithium ions
Data Source
AI summary
Disclosed are a negative electrode for a rechargeable lithium battery and a rechargeable lithium battery. The negative electrode includes lithium titanium oxide having an aspect ratio of about 10:1 to about 2:1, a needle-type carbon-based material and a negative active material.