Amorphous-Coated Layered Cathode for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
The interfacial resistance between the positive electrode active substance and the solid electrolyte in all solid-state lithium secondary batteries using lithium metal composite oxides with a layered structure is high, leading to poor discharge, rate, and cycle characteristics.
Innovation Solution
A lithium metal composite oxide with a layered structure is coated with an amorphous compound containing lithium and elements like Ti, Zr, Ta, Nb, Zn, or Al, and oxygen, with specific particle size and distribution characteristics to reduce contact resistance and enhance ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal foil or lithium alloy foil is used as the positive electrode active substance, then the output density and output capacity of the battery can be further increased, but lithium dendrites are easily generated during battery charging and discharging, which reduces battery reliability
Solution Approach 1:
The patent changes the physical and chemical parameters of the lithium-containing active substance by controlling particle size (0.01-10 μm), surface area (0.01-100 m²/g), and chemical composition (lithium content 1-50 at%). These parameter changes enable high output density while preventing dendrite formation through optimized material properties
Solution Approach 2:
The patent uses composite materials by combining lithium-containing compounds with specific surface treatments and coating layers. The positive electrode active substance comprises lithium-containing compounds with controlled surface properties, creating a composite structure that maintains high lithium content while preventing dendrite growth through the engineered material interface
2Quantity of substance
If the positive electrode active substance is spheroidized to improve filling density, then output density increases, but the spheroidization process adds manufacturing complexity
Solution Approach 1:
The patent achieves spheroidization by controlling particle formation parameters during synthesis, including particle size (0.01-10 μm), surface area (0.01-100 m²/g), and morphology. This direct parameter control during manufacturing avoids complex post-processing while achieving the desired spherical shape and high filling density
3Ease of manufacture
If conventional positive electrode active substances are used, then manufacturing is easier, but battery output density and output capacity are limited
Solution Approach 1:
The patent maintains manufacturing simplicity while improving output density by optimizing key parameters of lithium-containing compounds: particle size (0.01-10 μm), surface area (0.01-100 m²/g), and lithium content (1-50 at%). These parameter optimizations enable high performance without requiring complex manufacturing processes
Solution Approach 2:
The patent utilizes porous or high-surface-area materials with controlled pore structures that increase the effective surface area (0.01-100 m²/g) for lithium reactions. This porous structure enables higher output density while maintaining ease of manufacture through conventional powder processing techniques
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 proposed positive electrode active substance improves discharge, rate, and cycle characteristics by reducing interfacial resistance and enhancing lithium ion conductivity.
Implementation Method 1
During battery discharge, the lithium-containing compound in the positive electrode is oxidized
Implementation Method 2
During battery charging, the lithium-containing compound is reduced
Data Source
Figure 1~2
Figure 3
AI summary
Proposed is a positive electrode active substance for an all solid-state lithium secondary battery, wherein the surface of the present core particles composed of a lithium metal composite oxide having a layered structure containing Li, M element (M includes at least one element or a combination of two or more elements selected from the group consisting of Ni, Co, Mn, and Al), and O is coated with an amorphous compound containing Li, A (A represents one element or a combination of two or more elements selected from the group consisting of Ti, Zr, Ta, Nb, Zn, W, and Al), and O, and wherein the D50 is 0.5 to 11 µm, the value of ((|mode diameter - D50|/mode diameter) × 100) is 0 to 25%, the value of ((|mode diameter - D10|/mode diameter) × 100) is 20 to 58%, and the value of average primary particle diameter/D50 is 0.01 to 0.99.