SiOx Electrode Binder for Battery Cycle Life
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in cycle characteristics due to large volume changes in active materials like silicon, leading to electrode disconnection, SEI formation, and increased interfacial resistance, which deteriorate battery performance.
Innovation Solution
The use of a cathode electrode with a surface-modified silicon oxide (SiOx) active material, where the surface is modified with aniline, imidazole, or amino groups, and a water-soluble polymer binder with a sugar chain structure, such as sodium alginate, to improve binding properties and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase capacity, then the capacity increases significantly, but the volume change during charge and discharge causes electrode disconnection and deterioration of cycle characteristics
Solution Approach 1:
A flexible polymer binder comprising a sugar chain structure (such as carboxymethyl cellulose or sodium alginate) is used to bind the silicon-based active material particles. This flexible binder can accommodate the large volume changes of silicon during lithiation and delithiation, preventing electrode disconnection and maintaining cycle characteristics while preserving the high capacity benefit.
Solution Approach 2:
The invention uses a composite structure where silicon-based active material particles are bound together with a flexible polymer binder forming a three-dimensional network. This composite material combines the high capacity of silicon with the flexibility and binding strength of the polymer network, allowing the electrode to withstand volume changes without disconnection.
2Stability of the object's composition
If silane coupling agent is used to form stable SEI, then the SEI stability improves, but the electrode interfacial resistance increases and capacity decreases
Solution Approach 1:
The invention changes the chemical composition parameters of the binder from conventional options (such as polyvinylidene fluoride or carboxymethyl cellulose without sugar chain structure) to a specific flexible polymer binder comprising a sugar chain structure. This parameter change enables the formation of a stable SEI with lower interfacial resistance, simultaneously improving both SEI stability and capacity.
3Strength
If covalent bonding between binder and active material is used to prevent detachment, then the binding strength improves, but the coupling cannot be recovered after breakage
Solution Approach 1:
The invention employs a dynamic binding mechanism where the flexible polymer binder forms reversible physical crosslinks through hydrogen bonding and other non-covalent interactions. When the silicon particles expand or contract, these bonds can break and reform dynamically, providing self-recovery capability while maintaining strong binding strength throughout the charge-discharge 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
This configuration significantly enhances the cycle characteristics of lithium ion secondary batteries by improving binding properties and maintaining capacity over multiple charge-discharge cycles, reducing electrode resistance, and stabilizing the solid electrolyte interface.
Implementation Method 1
The active material and the binder are bound to each other due to an electrostatic mutual operation
Implementation Method 2
formation of a solid electrolyte interface (SEI) (a film that is generated in a case of using ethylene carbonate, and inactivates and stabilizes a surface of an active material so as to insert lithium therethrough)
Data Source
AI summary
An electrode for a secondary battery includes a current collector, and an active material layer being formed on a surface of the current collector, and containing an active material and a binder, in which the active material contains SiOx, a surface of SiOx is modified with one or more groups selected from the group consisting of an aniline group, an imidazole group, and an amino group, and the binder is constituted by a water-soluble polymer having a sugar chain structure that contains a carboxylic acid group.