All-Solid-State Battery Electrode Composition for Uniform Thick Coating
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Solution Overview
Problem
All-solid state secondary batteries face issues with interface resistance and electron/ion conductivity due to restricted interfacial contact between solid particles, leading to dripping and coating unevenness during film formation, which hinders the achievement of high ion conductivity and uniform layer thickness.
Innovation Solution
An electrode composition comprising an inorganic solid electrolyte, an active material, and a polymer binder with a specific relationship between the median diameter and rotation radius of the polymer binder, which suppresses dripping and coating unevenness while maintaining high ion conductivity, is developed. This composition includes a linear polymer with a specific SP value and adsorption rate, dissolved in a dispersion medium, and contains a silicon element and a sulfide-based inorganic solid electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrode material is applied to form a film, then coating coverage is achieved, but dripping and coating unevenness occur
Solution Approach 1:
The invention optimizes specific parameters of the electrode composition including the molecular weight, functional group content, and concentration of the polymer binder. By adjusting these parameters, the slurry achieves optimal viscosity and flow characteristics that prevent dripping during application while ensuring uniform coating. The functional groups on the polymer binder also enhance adhesion to the substrate, improving coating quality without sacrificing productivity.
2Reliability
If inorganic solid electrolyte and active material are combined, then high ion conductivity is achieved, but interfacial contact restriction increases
Solution Approach 1:
The polymer binder serves as a mediator between inorganic solid electrolyte particles and active material particles. It wets the particle surfaces and fills interstitial spaces, creating continuous conductive networks for both ions and electrons. This intermediary phase ensures intimate interfacial contact between the inorganic components while preserving their high ion conductivity properties.
Solution Approach 2:
The polymer binder is strategically positioned at the interfaces between solid particles where contact is needed. Rather than uniformly distributing throughout the entire structure, the binder concentrates at critical interfacial regions, providing localized improvement in contact quality exactly where it is most needed between inorganic solid electrolyte and active material particles.
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 electrode composition effectively forms a uniform and thick active material layer with high ion conductivity, preventing dripping and coating unevenness, even in high-productivity roll-to-roll methods, thereby enhancing the energy density and manufacturing efficiency of all-solid state secondary batteries.
Implementation Method 1
a polymer binder, and a dispersion medium, in which a linear polymer is contained to constitute the polymer binder
Implementation Method 2
an inorganic solid electrolyte having an ion conductivity of a metal belonging to Group 1 or Group 2 in the periodic table
Data Source
AI summary
There is provided an electrode composition that contains a polymer binder a polymer binder constituted by containing an inorganic solid electrolyte, an active material, and a linear polymer, and contains a dispersion medium, where in the electrode composition, a rotation radius α of the polymer binder and converted median diameters D50 of the inorganic solid electrolyte and the active material are present within a region (including a boundary line) of a polygonal shape having a point A to a point E as apices, in an orthogonal coordinate system in which the rotation radius α is on an x-axis and the median diameter D50 is on a y-axis. There are also provided an electrode sheet for an all-solid state secondary battery and an all-solid state secondary battery, and manufacturing methods for an electrode sheet for an all-solid state secondary battery and an all-solid state secondary battery, in which the electrode composition is used.