Lithium-Containing Silicon Negative Electrode Active Material
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Solution Overview
Problem
Lithium ion secondary batteries using silicon as a negative electrode material face challenges in achieving high battery capacity and cycle characteristics due to particle expansion, cracking, and electrolyte decomposition, leading to poor first time charge/discharge efficiency and cycle retention.
Innovation Solution
A production method for a negative electrode active material involving lithium-containing silicon compounds, where particles are treated with a solution containing lithium and ether-based solvents, followed by heating to stabilize the lithium insertion and form a carbon coating, optimizing the crystallite size and lithium content for improved efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as the negative electrode active material to improve battery capacity, then the theoretical capacity increases significantly, but particles expand and contract during charge/discharge causing cracks to occur
Solution Approach 1:
The patent applies the nesting principle by forming a core-shell structure where silicon particles are embedded within a carbon-containing layer. The silicon core provides high capacity while the surrounding carbon shell maintains structural integrity during expansion and contraction, preventing particle cracking and improving cycle characteristics.
Solution Approach 2:
The patent uses composite materials by combining silicon with carbon-containing materials to create a negative electrode active material. This composite structure allows the silicon to provide high theoretical capacity while the carbon component provides mechanical strength and structural stability, resolving the contradiction between capacity and particle integrity.
2Quantity of substance
If the superficial layer of particles is cracked due to expansion/contraction, then a new surface is generated increasing reaction area, but electrolytic solution is consumed through decomposition reactions
Solution Approach 1:
The patent applies preliminary action by pre-forming a carbon-containing coating layer on the silicon particle surface before electrochemical cycling begins. This pre-formed protective layer prevents direct contact between the electrolytic solution and the silicon surface, eliminating decomposition reactions and electrolyte consumption while still allowing lithium ion transport.
Solution Approach 2:
The carbon-containing layer serves as an intermediary between the silicon particles and the electrolytic solution. It mediates the interaction by providing a stable interface that allows lithium ion diffusion while preventing harmful decomposition reactions, thus maintaining reaction area without electrolyte consumption.
3Reliability
If a carbon material coating is provided on silicon oxide particles to improve safety and capacity, then battery performance improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges the carbon coating formation with the electrode manufacturing process itself. By incorporating carbon-containing materials into the slurry mixture and forming the coating during the standard electrode fabrication process (coating, drying, and heating), the patent achieves improved battery performance without adding separate complex manufacturing steps.
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 method enhances battery capacity, first time charge/discharge efficiency, and cycle characteristics by stabilizing the lithium insertion and reducing particle expansion, resulting in improved battery performance and stability.
Implementation Method 1
particles of silicon compound are brought into contact with a solution A to obtain particles of lithium-containing silicon compound
Implementation Method 2
the particles of silicon compound into which the lithium was inserted are brought into contact with a solution B or are heated
Implementation Method 3
among Li inserted in the Li insertion by soaking, a component that reacts with water used when forming a negative electrode slurry is changed to a substance thermodynamically more stable by a thermal process
Implementation Method 4
a carbon coating film is formed on the particles of silicon compound
Data Source
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AI summary
The present invention provides a production method of a negative electrode active material for non-aqueous electrolyte secondary batteries containing particles of lithium-containing silicon compound including: preparing particles of silicon compound containing a silicon compound (SiOx: 0.5≤x≤1.6); obtaining particles of lithium-containing silicon compound by making the particle of silicon compound contact with a solution A that contains lithium and has an ether-based solvent as a solvent; and heating the particles of the lithium-containing silicon compound. Thus, a production method of a negative electrode active material for non-aqueous electrolyte secondary batteries capable of increasing battery capacity of the negative electrode active material and capable of improving the first time efficiency and cycle characteristics is provided.