Positive Electrode Coating for Oxidation-Resistant Solid-State Batteries
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Solution Overview
Problem
All-solid-state batteries with halide solid electrolytes face oxidative degradation issues, leading to increased internal resistance and reduced charge and discharge capacity, especially when using positive electrode active materials with potentials greater than 3.9V.
Innovation Solution
A positive electrode material comprising a positive electrode active material with a composition of LiNixMn2−xO4, coated with a first solid electrolyte material containing Li, Nb, and O, and a second electrolyte material containing Li and Cl or Br, which enhances oxidation resistance and ionic conductivity, thereby reducing internal resistance and increasing charge and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halide solid electrolyte is used in all-solid-state battery, then ionic conductivity is improved, but oxidative degradation occurs leading to increased internal resistance
Solution Approach 1:
A protective coating layer comprising lithium niobate (LiNbO3) and lithium fluoride (LiF) is applied to the surface of the positive electrode active material. This intermediary layer prevents direct contact between the halide solid electrolyte and the positive electrode active material, thereby preventing oxidative degradation while maintaining ionic conductivity. The coating acts as a barrier that mediates the interaction between the electrolyte and electrode materials.
2Productivity
If positive electrode active material with potential greater than 3.9V is used, then charge and discharge capacity is improved, but oxidative degradation of halide solid electrolyte is accelerated
Solution Approach 1:
The protective coating of lithium niobate and lithium fluoride serves as an intermediary barrier that enables the use of high-potential positive electrode active materials (greater than 3.9V) without suffering from oxidative degradation. This coating allows the system to achieve high charge and discharge capacity while protecting against the harmful oxidation effects.
Solution Approach 2:
The protective coating is composed of a composite material system comprising lithium niobate (LiNbO3) and lithium fluoride (LiF). This composite structure combines the benefits of both materials: lithium niobate provides high ionic conductivity and structural stability, while lithium fluoride provides excellent chemical stability and oxidation resistance, creating a synergistic protective layer.
3Use of energy by moving object
If halide solid electrolyte is used, then battery energy density is improved, but charge and discharge capacity decreases due to oxidative degradation
Solution Approach 1:
The protective coating acts as an intermediary that preserves the high energy density benefits of halide solid electrolytes while preventing the oxidative degradation that would otherwise reduce charge and discharge capacity. By blocking the oxidation pathway, the coating maintains both energy density and productivity.
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 configuration significantly improves the oxidation resistance and ionic conductivity, leading to increased charge and discharge capacity and reduced internal resistance in batteries, particularly when used with positive electrode active materials having potentials greater than 3.9V.
Implementation Method 1
the first solid electrolyte material coats at least a portion of a surface of the positive electrode active material... the halide solid electrolyte oxidizes and degrades during charging
Implementation Method 2
the first solid electrolyte material contains Li, Nb, and O... the second electrolyte material contains Li and at least one selected from the group consisting of Cl and Br
Data Source
AI summary
A positive electrode material according to the present disclosure includes a positive electrode active material, a first solid electrolyte material coating at least a portion of a surface of the positive electrode active material, and a second electrolyte material. The second electrolyte material contains Li and at least one selected from the group consisting of Cl and Br, the first solid electrolyte material contains Li, Nb, and O, and the positive electrode active material contains a material represented by the following composition formula (1):LiNixMn2−xO4 Formula (1)where x satisfies 0<x<2.