Positive Electrode Layer Binder for Solid-State Battery Adhesion
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Solution Overview
Problem
The adhesiveness between the positive electrode active material layer and the current collector in solid-state batteries is insufficient due to the poor compatibility of traditional binders with solid electrolytes, leading to reduced charge/discharge efficiency.
Innovation Solution
Incorporating a specific vinylidene fluoride copolymer as a binder in the positive electrode active material layer, which contains a structural unit derived from vinylidene fluoride and another monomer, such as an unsaturated dibasic acid monoester, to enhance adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a traditional positive electrode binder used in liquid electrolyte batteries is used in a solid electrolyte battery, then the binder can maintain electrode structural integrity, but the adhesiveness between the positive electrode active material layer and the current collector becomes insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by selecting a vinylidene fluoride copolymer with specific monomer ratios (90-99 mol% vinylidene fluoride and 1-10 mol% of specific comonomers). This parameter change enables the binder to achieve both structural stability and strong adhesion to solid electrolytes, resolving the contradiction between maintaining electrode integrity and improving interfacial adhesiveness.
Solution Approach 2:
The invention uses a composite binder system comprising a vinylidene fluoride copolymer with specifically selected comonomers (unsaturated dibasic acid, unsaturated dibasic acid monoester, or compounds with carboxyl, hydroxyl, or amine groups). The composite nature of this binder combines the electrochemical stability of vinylidene fluoride with the enhanced bonding capability of the functional comonomers, simultaneously achieving structural integrity and strong adhesion to the current collector.
2Ease of manufacture
If a binder with poor adhesiveness to solid electrolyte is used, then the electrode can be manufactured with simple processes, but the charge/discharge efficiency cannot be stably realized
Solution Approach 1:
The invention optimizes the binder composition parameters by specifying the vinylidene fluoride content (90-99 mol%) and the type and amount of comonomers (1-10 mol%). These parameter changes ensure sufficient adhesion to solid electrolytes for stable charge/discharge efficiency while maintaining compatibility with conventional electrode manufacturing processes, thus achieving both ease of manufacture and operational reliability.
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 use of the vinylidene fluoride copolymer binder significantly improves the adhesiveness between the positive electrode active material layer and the current collector, stabilizing charge/discharge efficiency in solid-state batteries.
Implementation Method 1
adhesiveness between the positive electrode active material layer and a current collector
Data Source
AI summary
To provide: a positive electrode active material layer, with which a positive electrode having excellent adhesiveness between the positive electrode active material layer and a current collector can be formed; an electrode including the positive electrode active material layer; and a semi-solid-state battery or all-solid-state battery including the electrode. A positive electrode active material layer is used, which contains: a positive electrode active material (A); a solid electrolyte (B); and a binder (C), wherein the binder (C) is a vinylidene fluoride copolymer containing a structural unit (C-a) derived from vinylidene fluoride and a structural unit (C-b) derived from a monomer other than vinylidene fluoride, and the structural unit (C-b) derived from a monomer other than vinylidene fluoride contains a structural unit derived from at least one selected from an unsaturated dibasic acid, an unsaturated dibasic acid monoester, and a compound represented by the following formula (C-1), and an amount of the structural unit (C-a) derived from vinylidene fluoride is 90.0 mass% or more when a total amount of the structural units contained in the vinylidene fluoride copolymer is 100.0 mass%: where R1, R2 and R3 are each independently a hydrogen atom, a chlorine atom or an alkyl group having from 1 to 5 carbon atoms; and X1 is an atomic group having a main chain constituted of from 1 to 19 atoms and having a molecular weight of 472 or less, and containing at least one heteroatom selected from an oxygen atom and a nitrogen atom.