All-Solid Battery Grain Boundary Coating for Ionic Conduction
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Solution Overview
Problem
All-solid lithium ion batteries face challenges in achieving high current charge and discharge efficiency due to chemical compounds that inhibit ionic conduction at the interface between the electrode and solid electrolyte layers, and low electrical conductivity of electrode active materials, leading to insufficient reaction during calcination.
Innovation Solution
A coating layer with a thickness of 1 to 200 nm is applied to at least 30% of the grain boundary surrounding electrode active material particles, using materials like C, Au, Ag, Cu, Pd, Ru, Ni, Fe, Co, Mn, Ti, Sn, Al, and Si, to reduce reaction inhibition and enhance electrical conductivity, allowing for high current charge and discharge capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrode precursor and solid electrolyte precursor are calcined at the same time, then manufacturing cost is reduced and interface joining is improved, but chemical compounds that inhibit ionic conduction are generated at the interface
Solution Approach 1:
A coating layer is formed on the electrode precursor before calcination to prevent harmful reactions during the subsequent high-temperature treatment. This preliminary protective action allows the electrode and solid electrolyte to be calcined together without generating ionic conduction inhibitors at the interface.
Solution Approach 2:
A coating layer acts as an intermediary substance between the electrode and solid electrolyte during calcination. This intermediate layer prevents direct harmful chemical reactions while allowing ionic conduction to proceed, thus enabling simultaneous calcination without compromising ionic conduction capability.
2Strength
If high calcination temperature is used, then sintering of electrode and solid electrolyte is improved, but chemical compounds that inhibit ionic conduction are generated
Solution Approach 1:
The coating layer is applied to the electrode precursor before calcination to protect against harmful reactions at high temperatures. This preliminary protection enables the use of high calcination temperatures for improved sintering without generating ionic conduction inhibitors.
Solution Approach 2:
The coating layer serves as a protective intermediary that allows high-temperature calcination to proceed without generating harmful chemical compounds. It mediates between the high temperature environment and the electrode-solid electrolyte interface to prevent ionic conduction inhibition.
3Reliability
If low calcination temperature is used, then harmful chemical reactions are reduced, but sintering of electrode and solid electrolyte is insufficient
Solution Approach 1:
The coating layer is applied before calcination to enable low-temperature processing. This preliminary protection allows sufficient sintering to occur at lower temperatures without generating harmful chemical compounds that would inhibit ionic conduction.
4Power
If electrode active material with high reducing power is used, then electromotive force is increased, but reaction with solid electrolyte during calcination generates ionic conduction inhibitors
Solution Approach 1:
A coating layer is applied to the electrode active material with high reducing power before calcination to protect it from reacting with the solid electrolyte. This preliminary protection allows high electromotive force materials to be used without generating ionic conduction inhibitors at the interface.
Solution Approach 2:
The coating layer acts as an intermediary that prevents direct contact and harmful reactions between the high reducing power electrode active material and the solid electrolyte during calcination, while still allowing the high electromotive force characteristics to be maintained.
5Reliability
If coating layer is applied to grain boundary, then ionic conduction is improved, but manufacturing complexity increases
Solution Approach 1:
The coating layer is applied to the electrode precursor before calcination in a single integrated process step. This preliminary action forms the coating on grain boundaries during the normal calcination process, improving ionic conduction without adding significant manufacturing complexity.
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 high charge and discharge efficiency at large operation currents while reducing manufacturing costs by minimizing materials that inhibit ionic conduction and improving electron supply and emission in the electrode active material.
Implementation Method 1
a portion of at least 30% by area of a grain boundary surrounding the electrode active material particles has a coating layer with a thickness of 1 to 200 nm... there are extremely few materials that inhibit ionic conduction in an interface between an electrode layer and a solid electrolyte layer
Implementation Method 2
even in a case in which electrical conductivity of an electrode active material itself is low, supply and emission of electrons are performed well in the electrode active material
Implementation Method 3
in the interface between a solid electrolyte layer and an electrode layer, a reaction between the two layers would generate chemical compounds that inhibit ionic conduction
Data Source
AI summary
The all-solid battery has two electrode layers of a positive electrode and a negative electrode interposing a solid electrolyte layer therebetween, in which at least one of the electrode layers is composed of a sintered body of a mixed material including at least one or more types of electrode active material particles comprising electrode active material and solid electrolyte particles comprising solid electrolyte, and a portion of at least 30% by area of a grain boundary surrounding the electrode active material particles has a coating layer with a thickness of 1 to 200 nm.