Composite Anode Active Material for Lithium Battery
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Solution Overview
Problem
Lithium-ion batteries face limitations in initial efficiency, charge and discharge capacity, and lifespan due to the volume expansion of lithium-alloyable metal materials like Si, which leads to weak adhesion between the anode current collector and active material, resulting in decreased capacity and performance.
Innovation Solution
A composite anode active material is developed, comprising a crystalline carbonaceous material core with a shell portion of metallic core particles alloyable with lithium, coated with metal nitride in an island pattern to suppress volume expansion and side reactions, enhancing electrical conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-alloyable metal material (Si or Sn) is used alone to increase capacity, then theoretical discharge capacity is improved (Si: 4,200 mAh/g), but volume expansion of 300% or more occurs during charging and discharging, leading to weak adhesion and decreased capacity
Solution Approach 1:
The patent embeds lithium-alloyable metal particles (Si or Sn) inside carbonaceous material particles, creating a core-shell structure where the metal is nested within the carbon matrix. This nesting approach allows the high-capacity metal to be protected by the carbon shell, which constrains volume expansion and maintains structural integrity during charging-discharging cycles.
Solution Approach 2:
The patent creates a composite anode active material combining carbonaceous material (graphite, amorphous carbon, or carbon nanotubes) with lithium-alloyable metal particles (Si or Sn). The composite structure leverages the high capacity of the metal while the carbon matrix provides structural stability, electrical conductivity, and volume expansion buffer, resolving the contradiction between capacity and stability.
2Stability of the object's composition
If lithium-alloyable metal material is mixed with carbonaceous anode active material to compensate for capacity, then volume expansion is reduced, but improvements in capacity, lifespan characteristics, and initial efficiency characteristics are often negligible
Solution Approach 1:
The patent applies local quality by creating a heterogeneous structure where lithium-alloyable metal particles are distributed within the carbonaceous material matrix at specific concentrations (0.1-10 wt% of total anode active material). This localized distribution ensures that the metal provides high capacity where needed while the surrounding carbon matrix provides structural support and volume stability, achieving both high capacity and stable performance.
3Stability of the object's composition
If volume expansion is suppressed to maintain adhesion, then structural stability is improved, but electrical conductivity and initial efficiency may decrease
Solution Approach 1:
The patent optimizes the concentration of lithium-alloyable metal particles within a specific range (0.1-10 wt% of total anode active material) and controls the particle size distribution. By adjusting these parameters, the patent achieves a balance where the metal content is sufficient to provide high capacity and maintain electrical conductivity, while the carbon matrix provides structural stability and volume expansion control, ensuring both reliability and structural integrity.
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 composite anode active material improves initial efficiency, charge and discharge capacity, and lifespan characteristics by maintaining electrical conductivity and preventing excessive volume expansion, leading to more stable and efficient lithium battery performance.
Implementation Method 1
coating layer including metal nitride on the surface of the metallic core in an island pattern, suppressing volume expansion
Implementation Method 2
core portion including a crystalline carbonaceous material... improving initial efficiency, charge and discharge capacity... maintaining electrical conductivity
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A composite anode active material includes: a core portion including a crystalline carbonaceous material; a shell portion including a plurality of composite particles deposited on at least a portion of the core portion, wherein each of the composite particles includes a metallic core that is alloyable with lithium; and a coating layer including metal nitride on the surface of the metallic core in an island pattern. A lithium battery including the composite anode active material and a method of preparing the composite anode active material are also provided