Core-Shell Silicon Anode Material for Volume Expansion Buffering
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Solution Overview
Problem
Conventional lithium-ion batteries using silicon-based negative electrodes face issues such as rapid volume expansion, particle pulverization, and poor electronic conductivity, leading to degraded cycle life and high volume expansion rates, which limit energy density and rate performance.
Innovation Solution
A core-shell structured negative electrode material with a carbon layer and porous carbon core, incorporating silicon particles and inner pores, along with a metal element, to provide buffer space for volume expansion and enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as negative electrode to increase theoretical lithium storage capacity, then energy density is improved, but volume expansion exceeds 300% causing particle pulverization and electrode structure damage
Solution Approach 1:
The patent embeds silicon particles inside hollow porous carbon spheres, creating a nested structure where the inner pore provides buffer space for silicon expansion while the outer carbon shell maintains structural integrity. This nested configuration allows silicon to expand up to 300% volume without destroying the electrode structure.
Solution Approach 2:
The patent employs hollow porous carbon spheres with controlled porosity to accommodate silicon expansion. The porous structure provides internal void space that absorbs volume changes during lithium intercalation, preventing particle pulverization while maintaining electrode stability.
2Reliability
If carbon coating layer is constructed on silicon particle surface to buffer volume expansion, then cycling performance is improved, but carbon coating layer ruptures when silicon content exceeds 30%, causing rapid performance deterioration
Solution Approach 1:
The patent uses a hollow porous carbon shell that acts as a flexible container rather than a rigid coating. This shell can deform elastically to accommodate silicon expansion up to 300% without rupturing, maintaining integrity even at high silicon contents exceeding 30%.
Solution Approach 2:
The silicon particles are nested inside the hollow carbon sphere, allowing the carbon shell to contain and buffer the expansion forces. This nested arrangement distributes mechanical stress uniformly, preventing localized rupture of the carbon layer.
3Quantity of substance
If silicon content is increased to improve energy density, then lithium storage capacity is enhanced, but electronic conductivity decreases because silicon is a semiconductor
Solution Approach 1:
The patent creates a composite material system combining silicon particles with conductive carbon matrix. The carbon component provides excellent electronic conductivity while the silicon provides high capacity, achieving a synergistic effect where the composite outperforms individual components.
Solution Approach 2:
The conductive carbon shell acts as an intermediary between silicon particles and the electrolyte, providing electron transport pathways that compensate for silicon's poor conductivity. This intermediary layer enables efficient charge transfer while allowing lithium ion diffusion.
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 solution improves initial Coulombic efficiency, cycling stability, and rate performance while reducing volume expansion, resulting in a battery with high energy density and stability.
Implementation Method 1
after lithium intercalation, silicon undergoes volume expansion of over 300%
Implementation Method 2
silicon is a semiconductor, and electronic conductivity of the silicon also restricts rate performance of a lithium-ion battery
Data Source
AI summary
Disclosed are a negative electrode material, a negative electrode plate and a battery. The negative electrode material has a core-shell structure, a shell layer includes a carbon layer, a core includes porous carbon and silicon particles distributed in an outer pore of the porous carbon, the porous carbon further includes an inner pore, and the negative electrode material includes a metal element. The negative electrode material in the present disclosure can provide buffer space when lithium intercalation volume expansion occurs on silicon particles, and has high stability on an interface with an electrolyte solution interface. The negative electrode plate including the negative electrode material of the present disclosure has features of high specific capacity and high initial Coulombic efficiency. The battery including the negative electrode plate in the present disclosure has high energy density, high cycling stability, good rate performance, and a low volume expansion rate.