Silicon Anode Composite With Solid Electrolyte Coating for Cycle Stability
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in maintaining discharge capacity due to the expansion and contraction of alloyed materials like silicon during charge and discharge cycles, leading to reduced contact areas and potential deformation or separation from the current collector.
Innovation Solution
A negative electrode active material comprising silicon particles coated with a solid electrolyte containing lithium, titanium, phosphorus, and oxygen, along with a graphene compound, which helps maintain the structural integrity and conductivity of the electrode during cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as negative electrode material to increase theoretical capacity, then discharge capacity is improved, but structural stability deteriorates due to expansion and contraction during charge and discharge cycles
Solution Approach 1:
The patent applies nested structure by placing silicon particles inside a hollow core and coating them with solid electrolyte and graphene compound layers. This nested configuration allows the silicon to expand and contract within the protective hollow structure without damaging the electrode, while the solid electrolyte coating prevents direct contact between silicon and electrolyte solution. This resolves the contradiction by maintaining structural stability while preserving the high capacity of silicon.
Solution Approach 2:
The patent creates a composite material structure consisting of silicon particles, solid electrolyte coating, and graphene compound outer layer. This composite structure combines the high capacity of silicon with the structural stability and conductivity of graphene, and the protective properties of solid electrolyte. The composite material approach allows simultaneous achievement of high discharge capacity and structural stability during cycling.
2Quantity of substance
If amount of carrier ions received by silicon increases to increase capacity, then discharge capacity is improved, but contact area between active material and conductive additive is reduced
Solution Approach 1:
The patent uses a hollow shell structure with solid electrolyte coating and graphene compound film. This flexible shell configuration allows the silicon particles to expand and contract while maintaining continuous contact with conductive additives through the graphene network. The thin film structure ensures that even as silicon volume changes, the contact area with conductive additives is preserved through the flexible graphene matrix.
3Quantity of substance
If silicon particles are used to achieve high capacity, then energy density is improved, but reliability deteriorates due to deformation and separation from current collector
Solution Approach 1:
The patent applies beforehand cushioning by providing a hollow core structure that anticipates and accommodates the expansion of silicon particles during lithiation. The hollow space acts as a cushion that absorbs expansion stress, preventing deformation and separation from the current collector. This prior cushioning structure ensures reliability is maintained while achieving high energy density through silicon utilization.
4Stability of the object's composition
If solid electrolyte coating is applied to silicon particles to prevent expansion damage, then structural stability is improved, but electrical conductivity may be reduced
Solution Approach 1:
The patent applies local quality by using different materials with different properties in different locations: solid electrolyte coating where contact with electrolyte solution occurs (providing stability and protection), and graphene compound on the outer surface (providing electrical conductivity). This spatial differentiation of material properties allows simultaneous achievement of structural stability and electrical conductivity, resolving the contradiction between protection and energy loss.
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 active material effectively inhibits the reduction in capacity during charge and discharge cycles, maintains high capacity, and ensures excellent charge and discharge characteristics, safety, and reliability of the lithium-ion secondary battery.
Implementation Method 1
a particle, a solid electrolyte, and a graphene compound; in the negative electrode active material, the particle contains silicon, and the solid electrolyte contains lithium, titanium, phosphorus, and oxygen
Implementation Method 2
a particle, a solid electrolyte, and a graphene compound; in the negative electrode active material, the particle contains silicon, and the solid electrolyte contains lithium, titanium, phosphorus, and oxygen
Data Source
AI summary
A negative electrode active material with high capacity and excellent cycle performance and rate performance is provided. In addition, a secondary battery including the negative electrode active material, and an electronic device including the secondary battery are provided. Nanosilicon is mixed with a solid electrolyte containing lithium, titanium, phosphorus, and oxygen, and graphene oxide is further added thereto. Then, graphene oxide contained in the mixture is reduced with ethanol in which ascorbic acid and lithium hydroxide hydrate are dissolved, so that the negative electrode active material is manufactured.