Silicate-Silicon Anode Material for Stable Battery Cycling
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Solution Overview
Problem
Silicon-based negative electrode active materials in secondary batteries suffer from deterioration in charge/discharge cyclic characteristics due to large volume changes during reactions, leading to particle structure breakage.
Innovation Solution
A negative electrode active material comprising a silicate phase with specific compositions of Na, Si, and other elements, along with dispersed silicon particles, which reduces volume change and maintains ion conductivity, thereby preventing particle structure breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used as negative electrode active material to increase ion intercalation capacity, then the battery capacity is improved, but the charge/discharge cyclic characteristics deteriorate due to large volume changes causing particle structure breakage
Solution Approach 1:
The invention uses a composite material consisting of silicon particles dispersed in a glassy carbon matrix. The glassy carbon acts as a binding phase that holds the silicon particles together, preventing particle structure breakage during volume changes while still allowing ion intercalation. This composite structure resolves the contradiction by combining the high capacity of silicon with the structural stability of glassy carbon.
Solution Approach 2:
The glassy carbon matrix functions as a flexible binding phase that can accommodate the volume expansion and contraction of silicon particles during charge/discharge cycles. This flexible matrix prevents the silicon particles from breaking while maintaining structural integrity, thus improving cyclic characteristics without sacrificing capacity.
2Reliability
If glassy carbon is used as binding phase to improve particle structure stability, then the charge/discharge cyclic characteristics are improved, but the ion conductivity decreases
Solution Approach 1:
The invention applies local quality by having glassy carbon as the binding phase in specific regions where structural stability is needed, while maintaining silicon particles in regions where ion intercalation occurs. This localized arrangement ensures that glassy carbon provides structural support without completely blocking ion transport pathways, thus balancing stability and conductivity.
Solution Approach 2:
The invention optimizes the composition parameters of the glassy carbon matrix, specifically controlling the Na content (9-52 mol%) and Mx content (3-50 mol%), to achieve a balance between structural stability and ion conductivity. By adjusting these compositional parameters, the glassy carbon matrix provides sufficient mechanical support while maintaining adequate ion transport properties.
3Reliability
If the glassy carbon matrix composition is optimized for structural stability, then the particle structure is protected, but the manufacturing complexity increases
Solution Approach 1:
The invention defines specific compositional parameters for the glassy carbon matrix (Na content: 9-52 mol%, Mx content: 3-50 mol%, Si content: 25 mol% or more) that can be controlled during manufacturing. By establishing these clear parameter ranges, the invention makes it easier to reproduce the desired structural stability in production, reducing manufacturing complexity despite the sophisticated composition requirements.
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 effectively prevents the deterioration in charge/discharge cyclic characteristics by stabilizing the silicon particles within the silicate phase, enhancing battery performance and capacity retention.
Implementation Method 1
the volume change of the silicon particles due to the charge/discharge reaction is reduced by dispersion of the silicon particles in this silicate phase
Implementation Method 2
This silicate phase exhibits a good ion conductivity for ions such as lithium ions
Data Source
AI summary
A negative electrode active substance particle according to one embodiment of the present invention, comprises a mother particle that has: a silicate phase that includes Na, Si, and at least one element selected from M, M1, M2, M3 and M4 (M is an alkali earth metal, and M1, M2, M3 and M4 are elements other than alkali metals, alkali earth metals or Si); and silicon particles dispersed in the silicate phase. The contents of the elements in the silicate phase are: 9-52 mol % of Na; 3-50 mol % of M, M1, M2, M3 and M4; and at least 25 mol % of Si.