Silicon Oxide Multilayer Electrode With Conductive Infiltration
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Solution Overview
Problem
Silicon-based electrodes for lithium-ion secondary batteries face challenges due to significant volume changes during charging and discharging, which destroy the electrode structure and hinder high-capacity charging and discharging, despite silicon oxide showing promise as a negative electrode-active material with high theoretical capacity.
Innovation Solution
A multilayer body with a conductive substrate and a composite layer of silicon oxide particles less than 1.0 μm in diameter, where a conductive substance is infiltrated between the particles to form a conductive layer, enhancing conductivity and mitigating volume changes through the formation and decomposition of lithium silicide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon oxide is used as negative electrode-active material to achieve high theoretical capacity, then charging capacity is improved, but volume expansion and contraction during charging and discharging destroys electrode structure
Solution Approach 1:
The electrode structure is segmented into multiple layers: a conductive substrate, a silicon oxide layer formed by vapor deposition or sputtering, and a conductive coating layer. This segmentation allows each layer to perform its specific function - the substrate provides mechanical support, the silicon oxide layer provides high capacity, and the coating layer maintains conductivity during volume changes.
Solution Approach 2:
The patent uses composite material structure combining silicon oxide with conductive additives (such as carbon materials) and binders. The conductive coating layer contains conductive substance and binder that form a composite matrix, allowing the electrode to maintain structural integrity and conductivity despite the volume expansion and contraction of silicon oxide during lithiation and delithiation.
2Use of energy by moving object
If silicon oxide is used to achieve high charging capacity, then energy storage is improved, but insulating properties prevent effective electron transport
Solution Approach 1:
A conductive coating layer is introduced as an intermediary between the silicon oxide layer and the current collector. This coating layer contains conductive substances (such as carbon black, acetylene black, or other conductive additives) that form conductive pathways, mediating the electron transport from the silicon oxide particles to the current collector while allowing lithium ion insertion and extraction.
Solution Approach 2:
The electrode structure is designed with different local qualities: the silicon oxide layer provides high capacity regions, while the conductive coating layer provides conductivity pathways. The conductive coating is applied locally on the silicon oxide layer surface, creating a heterogeneous structure where each region performs its optimized function - energy storage where needed and electron transport where required.
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 enables lithium-ion secondary batteries with high capacity, improved safety, economic efficiency, and cycle characteristics by stabilizing the electrode structure and maintaining conductivity during charge and discharge cycles.
Implementation Method 1
forming a silicon oxide layer containing a plurality of particles of silicon oxide on a conductive substrate by vapor deposition or sputtering
Implementation Method 2
forming a silicon oxide layer containing a plurality of particles of silicon oxide on a conductive substrate by vapor deposition or sputtering
Implementation Method 3
applying a mixture containing a conductive substance and a binding agent onto the silicon oxide layer, infiltrating the conductive substance into the silicon oxide layer
Implementation Method 4
silicon expands and contracts during the lithiation and delithiation in charging and discharging
Implementation Method 5
silicon expands and contracts during the lithiation and delithiation in charging and discharging
Data Source
AI summary
A multilayer body is provided that is used as the negative electrode of a lithium-ion secondary battery that has a high capacity and is excellent in terms of safety, economic efficiency, and cycle characteristics. The multilayer body has a conductive substrate and a composite layer provided on the conductive substrate. The composite layer includes a plurality of particles of silicon oxide and a conductive substance present in gaps between the plurality of particles of silicon oxide. The average particle diameter of the particles of silicon oxide is 1.0 μm or less. The multilayer body further has a conductive layer that is provided on the composite layer and contains a conductive substance. The conductive layer has a thickness of 20 μm or less.