Carbon-Coated SiOx Anode Material Balancing Capacity and Cycling
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Solution Overview
Problem
Lithium-ion batteries face challenges with the large volume change of silicon-based materials during charge-discharge cycles, leading to poor conductivity and reduced cycling performance.
Innovation Solution
The development of a negative electrode material comprising silicon-based particles with a silicon oxide core coated with a carbon layer, optimized through specific Raman spectrum ratios and composition with graphite particles, to enhance the electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used as negative electrode material to increase capacity, then the energy density is improved, but the volume change during charge-discharge cycles causes poor conductivity and reduced cycling performance
Solution Approach 1:
The patent applies nested structure by placing silicon-based particles inside a carbon coating layer, forming a core-shell structure. The silicon-based particles (core) provide high capacity while the carbon coating (shell) constrains volume expansion and maintains conductivity. This nested configuration resolves the contradiction by allowing the silicon core to expand/contract within the protective carbon shell during charge-discharge cycles.
Solution Approach 2:
The patent uses composite materials by combining silicon-based materials with carbon coating and graphite particles. The composite structure integrates the high capacity advantage of silicon with the structural stability and conductivity of carbon and graphite, creating a material that maintains both high capacity and good cycling performance through synergistic properties of different materials.
2Quantity of substance
If silicon-based particles are used to increase capacity, then the energy density is improved, but the conductivity deteriorates due to volume change
Solution Approach 1:
The patent applies flexible shell concept by using a carbon coating layer that can accommodate the volume change of silicon-based particles during lithiation and delithiation. The carbon shell acts as a flexible protective layer that maintains electrical conductivity while allowing the silicon core to expand and contract, preventing conductivity deterioration despite capacity enhancement.
3Reliability
If carbon coating thickness is increased to improve conductivity and cycling performance, then the structural stability is improved, but the first efficiency is reduced
Solution Approach 1:
The patent applies parameter optimization by precisely controlling the carbon coating thickness within a specific range (5-50 nm). This parameter optimization balances two competing requirements: thick enough to provide structural stability and conductivity during cycling, but thin enough to allow sufficient lithium ion insertion/extraction for high first efficiency. The optimal thickness parameter resolves the contradiction between cycling performance and first efficiency.
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 optimized negative electrode material improves the first efficiency, cycling performance, and rate performance of lithium-ion batteries by controlling the carbon coating thickness, silicon-based particle distribution, and graphite particle proximity.
Implementation Method 1
a carbon layer, where the carbon layer covers at least a portion of a surface of the silicon oxide SiOx
Implementation Method 2
in a Raman spectrum, a ratio of a height I1350 of the silicon-based particles at a peak of approximately 1350 cm−1 to a height I1580 at a peak of approximately 1580 cm−1
Implementation Method 3
the large volume change of silicon-based materials during charge-discharge cycles
Data Source
AI summary
A negative electrode material of this application includes silicon-based particles, where the silicon-based particles include: a silicon oxide SiOx, where x is 0.5 to 1.6; and a carbon layer, where the carbon layer covers at least a portion of a surface of the silicon oxide SiOx. In a Raman spectrum, a ratio of a height I1350 of the silicon-based particles at a peak of 1350 cm−1 to a height I1580 at a peak of 1580 cm−1 satisfies 0<I1350/I1580<5, and a ratio of a height I510 at a peak of 510 cm−1 to the height I1350 at the peak of 1350 cm−1 satisfies 0<I510/I1350<12. A lithium ion battery prepared from the negative electrode active material has improved first efficiency, cycling performance, and rate performance.