Li-B-O Coated Cathode Material for Stable Solid-State Battery Interfaces
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Solution Overview
Problem
Existing positive electrode active materials for all-solid-state batteries react with sulfide-based solid electrolytes, forming resistive interfacial layers that degrade battery performance, particularly in high-nickel layered lithium transition metal oxides.
Innovation Solution
A positive electrode active material is developed with a lithium transition metal oxide core coated by a lithium boron oxide layer, maintaining a specific molar ratio of lithium to boron (Li:B) from 3:7 to 3:9, to prevent interfacial resistance and enhance charge and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If layered oxide-based positive electrode active materials (such as NCM-based or NCA-based materials) are used in combination with sulfide-based solid electrolytes, then high energy density and common lithium-ion battery performance are achieved, but interfacial reactions occur that form resistive interfacial layers degrading battery performance
Solution Approach 1:
A coating layer comprising lithium boron oxide (Li-B-O) is introduced as an intermediary between the layered oxide-based positive electrode active material and the sulfide-based solid electrolyte. This coating layer acts as a protective barrier that prevents direct contact and chemical reactions between the active material and electrolyte, thereby eliminating the formation of resistive interfacial layers while maintaining the high energy density characteristics of the underlying active material.
Solution Approach 2:
The positive electrode active material is structured as a composite system consisting of a core layered oxide-based active material (such as NCM or NCA) combined with a coating layer of lithium boron oxide. This composite structure integrates the high energy density properties of the layered oxide core with the protective interfacial stability provided by the Li-B-O coating, creating a material that simultaneously achieves both high performance and interfacial compatibility with sulfide-based solid electrolytes.
2Reliability
If surface-coating the active materials with lithium zirconium oxide or lithium niobium oxide is performed to prevent interfacial reactions, then interfacial stability is improved, but the charge and discharge capacity is reduced
Solution Approach 1:
The invention changes the chemical composition parameters of the coating layer from conventional lithium zirconium oxide or lithium niobium oxide to lithium boron oxide with a specific Li:B molar ratio ranging from 3:7 to 3:9. This parameter change in the coating material's stoichiometry results in a coating layer that provides interfacial stability while simultaneously maintaining higher charge and discharge capacity compared to the conventional coating materials.
3Productivity
If high-nickel layered lithium transition metal oxides are used to enhance capacity, then charge and discharge capacity is improved, but reactivity with sulfide-based solid electrolytes increases forming more resistive interfacial layers
Solution Approach 1:
The lithium boron oxide coating layer serves as a protective intermediary that specifically addresses the high reactivity of high-nickel layered lithium transition metal oxides with sulfide-based solid electrolytes. By preventing direct contact between the reactive high-nickel active material and the electrolyte, the coating layer eliminates the formation of resistive interfacial layers that would otherwise occur with high-nickel materials, thereby preserving their high charge and discharge capacity.
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 lithium boron oxide coating effectively suppresses the formation of high-resistance interfacial layers, improving charge and discharge capacities of the battery.
Implementation Method 1
the lithium boron oxide coating effectively suppresses the formation of high-resistance interfacial layers
Data Source
Figure 1
AI summary
The present invention relates to a positive electrode active material for an all-solid-state battery, comprising: a core comprising a lithium transition metal oxide; and a coating layer disposed on the core and comprising a lithium boron oxide, wherein a molar ratio of lithium to boron (Li:B) in the lithium boron oxide is from 3:7 to 3:9.