Silicon Oxide Negative Electrode Carbon Coating
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Solution Overview
Problem
Lithium-ion secondary batteries using silicon materials face challenges in achieving high battery capacity and cycle performance due to the expansion and contraction of silicon-based active material particles, leading to electrolyte decomposition and reduced cycle stability.
Innovation Solution
A negative electrode active material comprising silicon compound particles (SiOx where 0.5≤x≤1.6) coated with a carbon layer having a specific surface area of 5 m2/g to 1000 m2/g and compression resistivity of 1.0×10−3 Ω·cm to 1.0 Ω·cm, which enhances conductivity, impregnation, and binding properties, thereby improving battery capacity and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a negative electrode active material to increase battery capacity, then the battery capacity is improved, but the silicon-based active material particles expand and contract during charging and discharging, leading to particle breakage and reduced cycle performance
Solution Approach 1:
The patent applies composite materials by combining silicon-based active material particles with a carbon coating layer. The carbon coating forms a composite structure that maintains the high capacity benefits of silicon while providing mechanical strength to prevent particle breakage during expansion and contraction cycles, thereby improving cycle performance.
Solution Approach 2:
The patent uses a carbon coating layer as a flexible shell that conforms to the silicon-based active material particles. This thin film structure allows the coating to accommodate the expansion and contraction of the silicon particles during charging and discharging while maintaining structural integrity and preventing particle breakage.
2Quantity of substance
If the surface layer of silicon-based active material particles breaks during charging and discharging, then a new surface is created increasing reaction area, but this causes decomposition reaction of electrolyte and consumes electrolyte, reducing cycle performance
Solution Approach 1:
The patent applies preliminary anti-action by pre-coating the silicon-based active material particles with a carbon layer before they are used in the battery. This pre-established coating prevents the harmful decomposition reaction of the electrolyte that would otherwise occur when new surfaces are created during particle breakage, while still allowing necessary electrochemical reactions to proceed.
Solution Approach 2:
The carbon coating layer acts as an intermediary between the silicon-based active material particles and the electrolyte. It mediates the interaction by providing a stable interface that allows lithium ion transport while preventing direct contact between the electrolyte and the reactive silicon surface, thereby preventing unwanted decomposition reactions.
3Reliability
If a carbon coating is applied to silicon compound particles to improve conductivity and prevent particle breakage, then cycle performance is improved, but the specific surface area and compression resistivity of the carbon coating must be precisely controlled
Solution Approach 1:
The patent applies parameter changes by specifying precise ranges for the specific surface area (5-1000 m²/g) and compression resistivity (1.0×10⁻³ to 1.0 Ω·cm) of the carbon coating. By controlling these physical parameters within defined ranges, the patent optimizes both the conductivity and mechanical strength of the carbon coating to achieve improved cycle performance.
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 significantly increases battery capacity and retains initial efficiency, with the carbon coating providing excellent conductivity and preventing surface lithium precipitation, resulting in improved cycle performance and capacity retention.
Implementation Method 1
the carbon coating exhibiting a compression resistivity ranging from 1.0×10−3 Ω·cm to 1.0 Ω·cm
Implementation Method 2
a carbon material, an electronic conduction material, is disposed on the surface of silicon oxide particles
Data Source
AI summary
A negative electrode active material for a non-aqueous electrolyte secondary battery, including negative electrode active material particles containing a silicon compound expressed by SiOx where 0.5≤x≤1.6, the negative electrode active material particles at least partially coated with a carbon coating, the carbon coating exhibiting a specific surface area ranging from 5 m2/g to 1000 m2/g, the specific surface area being measured by a multipoint BET method after the carbon coating is separated from the negative electrode active material particles, the carbon coating exhibiting a compression resistivity ranging from 1.0×10−3 Ω·cm to 1.0 Ω·cm when the carbon coating is compressed so as to have a density of 1.0 g/cm3, the compression resistivity being measured after the carbon coating is separated from the negative electrode active material particles. This negative electrode active material can increase the battery capacity and improve the cycle performance and battery initial efficiency.