Boron-Doped Carbon-Silicon Anode for Battery Cycle Stability
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Solution Overview
Problem
Silicon and silicon oxide negative electrode active materials for batteries experience significant volume expansion and shrinkage during charging and discharging, leading to cracking and detachment, which degrades cycle characteristics and reduces discharge capacity density.
Innovation Solution
A negative electrode active material comprising a carbon material with boron, where the boron is specifically incorporated to form bonds within the carbon layer, reducing electron density and enhancing the interaction with silicon or silicon oxide, thereby forming a stable electron-conduction network and maintaining high discharge capacity density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon or silicon oxide is used as negative electrode active material, then discharge capacity density is improved, but cycle characteristics deteriorate due to volume expansion and shrinkage causing cracking and detachment
Solution Approach 1:
The patent uses a composite structure where silicon or silicon oxide particles are embedded in a carbon matrix. The carbon material serves as a stable framework that accommodates the volume changes of silicon/silicon oxide during charging and discharging, preventing particle detachment and maintaining electrical conductivity, thus improving cycle characteristics while preserving high discharge capacity density.
Solution Approach 2:
The carbon material forms a flexible matrix that can elastically deform to accommodate the significant volume expansion (up to 410%) of silicon during lithiation. This flexible carbon shell/constraint structure prevents mechanical failure of the silicon particles and maintains structural integrity over multiple cycles, resolving the contradiction between high capacity and cycle stability.
2Reliability
If carbon material with boron is used to form stable electron-conduction network, then cycle characteristics are improved, but manufacturing precision requirements increase due to specific boron incorporation needs
Solution Approach 1:
The patent specifies precise parameters for boron incorporation in carbon material (binding energy of 187.0-192.0 eV in B1s spectrum, ratio of 50% or more) to ensure optimal electron-conduction network formation. By controlling these chemical parameters, the patent achieves improved cycle characteristics while providing clear manufacturing specifications that make precision control achievable through standardized production processes.
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 achieves improved cycle characteristics and maintains high discharge capacity density by forming a strong electron-conduction network between the carbon material with boron and silicon or silicon oxide, reducing internal resistance and preventing material breakage.
Implementation Method 1
the boron is specifically incorporated to form bonds within the carbon layer, reducing electron density and enhancing the interaction with silicon or silicon oxide, thereby forming a stable electron-conduction network
Implementation Method 2
A peak of a B1 s spectrum of the carbon material which is measured by X-ray photoelectron spectroscopy occurs at a binding energy of 187.0 eV or more and 192.0 eV or less
Data Source
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AI summary
A negative electrode active material includes a carbon material including boron and a silicon material including at least one selected from silicon and silicon oxide. The silicon material does not include boron. A peak of a B1s spectrum of the carbon material occurs at a binding energy of 187.0 eV or more and 192.0 eV or less, the B1s spectrum being measured by X-ray photoelectron spectroscopy. The ratio of the area of the peak of the B1s spectrum of the carbon material which occurs at a binding energy of 187.0 eV or more and 192.0 eV or less, the B1s spectrum being measured by X-ray photoelectron spectroscopy, to the total area of peaks of the B1s spectrum which occur at a binding energy of 184.0 eV or more and 196.5 eV or less is 50% or more.