Si Clathrate Anode Composition for Stable Restraint Pressure
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Solution Overview
Problem
Silicon (Si) active materials in lithium-ion batteries experience significant volume expansion and contraction during charging and discharging, leading to variations in restraint pressure, which can cause damage and reduce energy efficiency.
Innovation Solution
A negative electrode body for lithium-ion batteries is developed, incorporating Si particles with a clathrate type structure and containing 0.040-0.250 mass% Al, which reduces expansion and contraction by introducing Al-containing particles like AlF3 or Al2O3, and a production method involving mixing NaSi alloy with AlF3, followed by heating and washing with HNO3 solution to create a stable active material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Si particles are used as active material to increase energy density, then battery energy density is improved, but volume expansion and contraction during charging and discharging increases causing restraint pressure variation
Solution Approach 1:
The patent uses composite materials by combining Si particles with a clathrate structure (which provides volume expansion space) and Al-containing particles (which suppress excessive expansion). This composite approach allows the battery to achieve high energy density from Si while the Al-containing particles act as a constraint to reduce restraint pressure variation during charging-discharging cycles.
Solution Approach 2:
The patent applies local quality by creating Al-containing particles with specific composition (Al, F, O) that are distributed within the negative electrode active material layer. These localized Al-containing regions provide targeted suppression of Si particle expansion at critical points, while the overall Si clathrate structure maintains high energy density capabilities.
2Duration of action of moving object
If Si particles undergo volume expansion and contraction during charging and discharging, then lithium ion insertion and extraction is enabled, but pulverization and damage occur reducing battery reliability
Solution Approach 1:
The patent employs beforehand cushioning by incorporating Al-containing particles before the charging-discharging process begins. These Al-containing particles are positioned in advance to suppress and cushion the volume expansion of Si particles during lithium insertion, preventing structural damage before it occurs. The Al-containing particles act as a pre-positioned protective mechanism against pulverization.
3Stability of the object's composition
If Al-containing particles are introduced to suppress Si particle expansion, then restraint pressure variation is reduced, but manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by performing all necessary processing of Al-containing particles and Si clathrate particles during the manufacturing stage. The Al-containing particles are prepared with specific composition (Al, F, O) and distributed within the negative electrode active material layer before battery assembly. This preliminary preparation eliminates the need for complex post-manufacturing adjustments or specialized handling during battery operation.
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 approach effectively reduces the variation in restraint pressure during charging and discharging, enhancing the energy efficiency and stability of the battery by restricting Si particle expansion and minimizing pulverization.
Implementation Method 1
Al is introduced into Si particles having a clathrate type structure, thereby obtaining Si particles which have a small change in volume due to charging and discharging
Implementation Method 2
mixing and heating a NaSi alloy and AlF3 to obtain a mixture containing Si particles having a clathrate type structure, NaF, and Al-containing particles
Implementation Method 3
washing the mixture with an aqueous HNO3 solution, and then performing filtering and drying
Data Source
AI summary
A negative electrode body of the present disclosure is a negative electrode body for a lithium ion battery having a negative electrode current collector layer and a negative electrode active material layer, wherein the negative electrode active material layer contains Si particles having a clathrate type structure as a negative electrode active material, wherein the negative electrode active material layer contains 0.850 mass % to 5.000 mass % of Al with respect to a mass of the negative electrode active material layer, and wherein the Si particles contain 0.040 mass % to 0.250 mass % of Al with respect to a mass of the Si particles.