Amorphous-Coated Spinel 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 is high, which hinders the improvement of rate characteristics and cycle characteristics.
Innovation Solution
A positive electrode active substance is developed, where the surface of spinel-type composite oxide particles containing Li, Mn, O, and additional elements is coated with an amorphous compound containing Li, A elements (such as Ti, Zr, Ta, Nb, Zn, W, and Al), and O. This structure aims to reduce contact resistance and maintain high operating voltage during discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte is used in all solid-state lithium secondary batteries, then safety is improved and production cost is reduced, but interfacial resistance between the positive electrode active substance and solid electrolyte increases
Solution Approach 1:
A lithium ion-conducting oxide layer is introduced as an intermediary between the positive electrode active substance and the solid electrolyte. This intermediate layer facilitates lithium ion transport across the interface while maintaining the safety benefits of the solid electrolyte system, effectively resolving the interfacial resistance problem without sacrificing safety.
Solution Approach 2:
The positive electrode active substance is designed as a composite structure with a coating layer containing lithium ion-conducting oxide. This composite material approach combines the high capacity benefits of the base active substance with the improved interfacial properties of the lithium ion-conducting oxide coating, achieving both low interfacial resistance and high performance.
2Use of energy by moving object
If the operating potential of the positive electrode is increased to 4.5 V or more, then energy density is improved, but a high resistant layer is formed by reaction with solid electrolyte
Solution Approach 1:
The lithium ion-conducting oxide coating layer serves as a protective intermediary that prevents direct harmful reactions between the high-potential positive electrode active substance and the solid electrolyte. This intermediate layer allows the system to operate at high potentials (4.5 V or more) for improved energy density while preventing the formation of high resistant reaction layers.
Solution Approach 2:
The coating layer modifies the electrochemical parameters at the interface, creating a stable environment that prevents resistance increase even when operating at high potentials. This allows the battery to maintain high energy density through elevated operating potentials without suffering from degradation.
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 effectively enhances lithium ion conductivity, suppresses resistance, and improves rate and cycle characteristics by reducing contact resistance and maintaining a high operating voltage during discharge.
Implementation Method 1
The solid electrolyte is required to have high ionic conductivity as far as possible... lithium halide, lithium nitride, lithium acid salt, derivatives of these compounds, and the like are known as candidate materials for the solid electrolyte
Data Source
AI summary
A positive electrode active substance for an all solid-state lithium secondary battery having an operating potential of 4.5 V or more at a metal Li reference potential, wherein the surface of the present core particles composed of a spinel-type lithium manganese-containing composite oxide containing at least Li, Mn, O, and two or more elements other than these is coated with an amorphous compound containing Li, A, where 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. Primary particles of the present core particles are composed of a polycrystal. The D50 is 0.5-9 μm, the value of (|mode diameter−D50|/mode diameter)×100 is 0 to 25%, the value of (|mode diameter−D10|/mode diameter)×100 is 20-58%, and the value of the average primary particle diameter/D50 is 0.20-0.99.