Silicon Negative Electrodes with SiO and LiPON Coatings
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Solution Overview
Problem
Silicon-based negative electrodes in lithium-ion batteries face significant irreversible capacity loss and structural degradation due to the formation of an unstable solid electrolyte interface (SEI), leading to poor cycle stability and increased internal resistance.
Innovation Solution
A silicon-based active material with silicon particles coated twice, once with silicon oxide and then with LiPON, is used to create a stable and conductive artificial SEI, enhancing adhesion and distribution on the electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase energy density, then capacity increases, but irreversible capacity loss increases due to unstable SEI formation
Solution Approach 1:
A silicon oxide layer is deposited on the silicon particles before battery assembly. This preliminary coating prevents direct contact between silicon and electrolyte during initial cyclings, controlling SEI formation and reducing irreversible capacity loss while preserving the high capacity benefits of silicon
Solution Approach 2:
The silicon oxide layer acts as an intermediary between the silicon active material and the electrolyte. It mediates the interaction by providing a stable interface that allows controlled ion transport while preventing harmful direct reactions, thus reducing capacity loss
2Quantity of substance
If silicon-based negative electrode is used, then energy density increases, but service life decreases due to structural degradation
Solution Approach 1:
The silicon oxide coating is applied in advance to protect the silicon particles from structural degradation during battery cycling. This preliminary protective measure prevents particle pulverization and maintains electrode integrity over extended service life
Solution Approach 2:
The silicon oxide layer provides beforehand cushioning against the mechanical stresses and chemical attacks that occur during battery operation. It absorbs and distributes stresses that would otherwise cause particle fracture and electrode degradation
3Reliability
If thick SEI layer forms on silicon electrode, then electrical insulation improves, but ionic conductivity decreases
Solution Approach 1:
The silicon oxide coating provides local quality control by creating a uniform, thin protective layer with optimized properties. This localized coating ensures adequate electrical insulation while maintaining sufficient ionic conductivity through its controlled thickness and composition
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 double-coated silicon particles improve the service life of silicon-containing electrodes by maintaining high electrical insulation and ionic conductivity, reducing capacity loss and internal resistance, and extending cycle stability.
Implementation Method 1
maintaining high electrical insulation
Implementation Method 2
maintaining high ... ionic conductivity
Implementation Method 3
reducing capacity loss and internal resistance, and extending cycle stability
Data Source
AI summary
The present invention relates to silicon-based active material for negative electrodes, in particular electrodes with increased service life, in particular for use in batteries, a method for their manufacture, and negative electrodes, batteries, and devices that contain this silicon-based active material.