MXene-Coated Silicon Anode Material for Conductive Battery Electrodes
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Solution Overview
Problem
Silicon particles used as negative electrode active material in lithium secondary batteries have low electrical conductivity, requiring a large amount of conductive material, which reduces energy density, and existing coating methods like graphene application cause defects and lower conductivity.
Innovation Solution
A silicon-based negative electrode active material is formed by coating silicon particles with cetyltrimethylammonium and MXene, where MXene has a hydroxyl group on its surface, improving bonding and conductivity through electrostatic attraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used as negative electrode active material, then battery energy density is improved, but electrical conductivity is insufficient requiring large amount of conductive material
Solution Approach 1:
The patent applies composite materials by combining silicon particles with MXene (a two-dimensional transition metal carbide) to create a core-shell structure. The MXene coating layer provides excellent electrical conductivity while maintaining the high capacity benefits of silicon, eliminating the need for excessive conductive additives.
Solution Approach 2:
The patent changes the surface properties of silicon particles by coating them with MXene, which has superior electrical conductivity parameters. This parameter change in the coating material directly addresses the conductivity issue while preserving silicon's high energy density characteristics.
2Reliability
If graphene is used as coating material on silicon particles, then electrical conductivity is improved, but defects are easily caused reducing conductivity
Solution Approach 1:
The patent replaces graphene with MXene, which can be more easily and uniformly deposited without the defect-prone processes associated with graphene transfer methods. MXene's unique properties allow for direct coating that maintains high conductivity without the manufacturing complexities.
Solution Approach 2:
The patent changes the coating material from graphene to MXene, utilizing MXene's superior processability and defect-free deposition characteristics. This material substitution resolves the manufacturing precision issues while maintaining or improving electrical conductivity.
3Strength
If polymer binder is included in coating material to increase bonding force, then bonding strength is improved, but conductivity is reduced
Solution Approach 1:
The patent extracts the polymer binder from the coating material system, relying instead on the intrinsic adhesive properties of MXene and its strong interaction with silicon particles. This elimination of polymer binder maintains bonding strength while preserving electrical conductivity.
Solution Approach 2:
The patent uses the composite nature of MXene-silicon structure where MXene provides both bonding strength through surface interactions and electrical conductivity through its conductive network, eliminating the need for polymer binders that would compromise conductivity.
4Reliability
If carbon coating layer is formed on silicon particles, then conductivity is improved, but amount of negative electrode active material is reduced
Solution Approach 1:
The patent applies local quality by using a thin MXene coating layer that provides conductivity enhancement only at the surface of silicon particles, while the bulk silicon material retains its high capacity properties. This localized approach maximizes active material content while improving conductivity.
Solution Approach 2:
The patent employs a core-shell composite structure where the silicon core provides high capacity and the thin MXene shell provides conductivity, optimizing the ratio of active material to conductive material more effectively than bulk carbon coatings.
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 material enhances electrical conductivity and structural stability, improving rate and lifespan characteristics of batteries by maintaining strong bonding despite volume changes during operation.
Implementation Method 1
MXene disposed on the core and including a hydroxyl group on a surface thereof, wherein the MXene comprising a hydroxyl group on the surface thereof comprises the hydroxyl group in an amount of 1 wt% to 10 wt%
Data Source
AI summary
The present invention relates to a silicon-based negative electrode active material that includes a core containing silicon particles and cetyltrimethylammonium disposed on a surface of the silicon particles, and MXene disposed on the core and including a hydroxyl group on a surface thereof, a method of preparing the silicon-based negative electrode active material, a negative electrode including the silicon-based negative electrode active material, and a secondary battery including the negative electrode.