Silicate-Skeleton Silicon Anode for Volume Expansion Control
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Solution Overview
Problem
Silicon-based negative electrodes face challenges with severe volume expansion and poor cycling performance due to structural instability, despite efforts in nanocrystallization, porous structure design, and doping, which hinder the achievement of high energy density required for new energy vehicles.
Innovation Solution
A Silicon-based negative electrode material with a silicate skeleton is developed by dispersing a silicate material within the SiOx material, forming a stable skeleton structure that alleviates deformation stress and improves cycling performance by preventing physical and chemical reactions during lithium intercalation and deintercalation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metallic silicon is used as negative electrode material to achieve high capacity density (4200 mAh/g), then the energy density is improved, but the volume expansion reaches about 300% during lithium intercalation, leading to structure collapse and poor cycling performance
Solution Approach 1:
The patent divides the negative electrode material into two functional components: SiOx particles (providing capacity) and silicate material (providing structural stability). This segmentation allows each component to perform its specific function - SiOx delivers high capacity while silicate maintains structural integrity during cycling, resolving the contradiction between capacity density and cycling performance
Solution Approach 2:
The patent creates a composite material system consisting of SiOx particles dispersed in a silicate matrix. The silicate material forms a stable skeleton that constrains the volume expansion of SiOx during lithium intercalation, while still allowing the SiOx to provide high capacity. This composite structure simultaneously achieves both high capacity density and excellent cycling performance
2Stability of the object's composition
If SiOx is used to reduce volume expansion, then the cycling performance is improved, but the capacity is reduced compared to metallic silicon
Solution Approach 1:
The patent applies local quality by having different regions perform different functions: the SiOx particles (occupying about 30% of the composite) provide high capacity in their local regions, while the silicate material (occupying about 70%) provides structural stability and volume constraint in its regions. This local differentiation allows the material to achieve both high capacity and excellent cycling performance simultaneously
3Stability of the object's composition
If nanocrystallization and porous structure design are applied to reduce volume expansion, then the cycling performance is improved, but the structural stability and dispersion of nanoparticles remain challenging for large-scale preparation
Solution Approach 1:
The patent changes the structural parameter from complex nanocrystalline or porous designs to a simpler composite structure where SiOx particles are dispersed in a silicate matrix. The silicate material naturally forms a stable skeleton structure that provides volume constraint without requiring complex nanoscale engineering, making the material easier to manufacture at large scale while maintaining excellent cycling performance
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 silicate skeleton effectively enhances the cycling performance of the Silicon-based negative electrode, leading to improved capacity retention rates and structural stability even after multiple cycles, addressing the limitations of existing Si-based negative electrodes.
Implementation Method 1
The silicate skeleton can generate a pinning effect on the volume expansion of the Si-based negative electrode, so as to alleviate deformation stress
Implementation Method 2
When lithium is intercalated in the first cycle, lithium reacts with SiO2 to generate a variety of irreversible lithium oxides
Data Source
AI summary
A silicon-based negative electrode material containing a silicate skeleton, a negative electrode plate and a lithium battery. The silicon-based negative electrode material comprises a modified silicon monoxide material having a dispersedly distributed silicate material inside same. The general formula of the modified silicon monoxide material is MxSiOy, with 1<x<6, 3<y<6, element M comprising one or more of Mg, Ni, Cu, Zn, Al, Na, Ca, K, Li, Fe and Co, and the grain size being 0.5-100 nm. In the modified silicon monoxide material, the content of the silicate material is 5-60% of the total mass of the modified silicon monoxide material. The dispersedly distributed silicate material forms a skeleton structure of the silicon-based negative electrode material, does not undergo a physicochemical reaction along with the lithium removal and lithium intercalation of the silicon-based negative electrode material in the cycle process, and maintains the original structure thereof after multiple cycles.