Li-Containing Silicon Oxide Anode Particles for Capacity and Cycle Life
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Solution Overview
Problem
Lithium-ion secondary batteries using silicon materials face challenges in achieving cycle characteristics equivalent to those of carbon-based active materials, with silicon materials exhibiting inferior cycle characteristics and no proposed solution has yet met the requirements for equivalent performance.
Innovation Solution
A negative electrode active material comprising a silicon compound particle with a Li compound, where at least part of Si is present in oxide states of Si2+ to Si3+ containing no Li, and compounds containing Li and Si2+ to Si3+, along with a carbon material coating, to improve battery capacity and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a negative electrode active material to improve battery capacity, then the battery capacity increases significantly, but the cycle characteristics deteriorate due to material breakage and electrolyte decomposition
Solution Approach 1:
The patent uses a composite material structure consisting of silicon oxide particles coated with carbon material. The silicon oxide provides high capacity while the carbon coating prevents breakage and electrolyte decomposition, resolving the contradiction between capacity and cycle characteristics
Solution Approach 2:
The patent controls the oxygen-to-silicon mole ratio in the range of 0.1 to 1.2 and maintains a difference of 0.4 or less near the current collector interface. This parameter optimization allows the material to achieve both high capacity and good cycle characteristics by balancing the properties of silicon and silicon oxide
2Quantity of substance
If the surface layer of negative electrode active material breaks during charging and discharging, then the reaction area increases, but the cycle characteristics reduce due to electrolyte consumption
Solution Approach 1:
The patent applies a carbon material coating layer on the surface of silicon oxide particles. This thin film coating prevents direct contact between the active material and electrolyte, avoiding decomposition reactions while maintaining electrochemical performance and preventing material breakage
Solution Approach 2:
The carbon coating is applied in advance to prevent the harmful effect of electrolyte decomposition. By pre-coating the surface, the patent prevents the breakdown that would otherwise occur during charging and discharging cycles
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 enhances battery capacity and cycle characteristics by stabilizing the phase structure during charging and discharging, reducing irreversible capacity, and improving electric conductivity, resulting in high-capacity and long-lasting battery performance.
Implementation Method 1
stabilizing the phase structure during charging and discharging
Implementation Method 2
improving electric conductivity
Data Source
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AI summary
The present invention is a negative electrode active material containing a negative electrode active material particle which includes a silicon compound particle containing a silicon compound that contains oxygen. The silicon compound particle contains a Li compound, and at least part of Si constituting the silicon compound particle is present in at least one state selected from oxide of Si2+ to Si3+ containing no Li, and compound containing Li and Si2+ to Si3+. This provides a negative electrode active material capable of increasing battery capacity and improving cycle characteristics and initial charge-discharge characteristics when the negative electrode active material is used for a secondary battery; a mixed negative electrode active material containing the negative electrode active material; and a method for producing a negative electrode active material particle which enables production of the negative electrode active material particle to be contained in the negative electrode active material as described above.