Coated Cathode Particles for Stable High-Voltage Solid-State Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High energy density all-solid-state batteries face compatibility issues due to cathode active materials with redox potentials of 4 V or more, which can oxidize typical lithium ion-conducting solid electrolytes, leading to instability and capacity loss during cycling.
Innovation Solution
A coated particulate material is developed, featuring core particles with specific compositions like Li1+t[CoxMnyNizMu]1−tO2 and a coating comprising carbonate anions, lithium cations, niobium, and zinc in oxidized form, particularly with cubic Li3NbO4, to protect the solid electrolyte while allowing lithium ion transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If cathode active material with redox potential of 4 V or more is used, then high cell voltage and high energy density are achieved, but the cathode material oxidizes the solid electrolyte causing instability and capacity loss
Solution Approach 1:
A coating layer comprising Li3NbO4 and Li6ZnNb4O14 is applied to the cathode active material surface. This coating acts as an intermediary between the high-potential cathode material (4 V class) and the solid electrolyte, preventing direct oxidative reactions while maintaining lithium ion conductivity. The coating enables the use of high-voltage cathode materials without compromising cycling stability.
2Reliability
If a coating is applied to protect the solid electrolyte, then cycling stability is improved, but lithium ion transfer between cathode material and solid electrolyte may be inhibited
Solution Approach 1:
The coating layer is designed with a porous structure containing nanoscale voids and channels that allow lithium ion diffusion. This porous architecture provides protection against oxidation while maintaining adequate lithium ion conductivity, resolving the contradiction between protection and ion transfer.
Solution Approach 2:
The coating is composed of a composite system with Li3NbO4 as the primary protective phase and Li6ZnNb4O14 as a secondary phase. This composite structure combines the oxidation resistance of Li3NbO4 with the enhanced lithium ion conductivity provided by Li6ZnNb4O14, achieving both protection and efficient ion transfer.
3Productivity
If typical lithium ion-conducting solid electrolyte materials are used, then good lithium ion conductivity is achieved, but they are incompatible with high-voltage cathode materials due to oxidation
Solution Approach 1:
The Li3NbO4-based coating serves as an intermediary layer that decouples the requirements of the solid electrolyte and cathode material. It allows typical lithium ion-conducting solid electrolytes to be used with high-voltage cathode materials by preventing direct chemical reactions while maintaining ionic conductivity pathways.
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 coated particulate material enhances initial discharge capacity and cycling stability, reducing capacity loss and maintaining high performance over 200 cycles with improved lithium ion conductivity and reduced interfacial resistance.
Implementation Method 1
the cathode active material may act as an oxidizing agent towards the solid electrolyte present in the cathode and/or in the separator layer
Implementation Method 2
at least a part of the niobium is present as cubic Li3NbO4 having a crystallographic unit cell of space group Fm-3m
Data Source
AI summary
Described are a coated particulate material for use in an electrode of an electrochemical cell and a process for preparing said coated particulate material, an electrode comprising said coated particulate material for use in an electrochemical cell, an electrochemical cell comprising said coated particulate material, and a use of said coated particulate material for preparing an electrode for use in an electrochemical cell.