Fluoride-Coated Positive Electrode Material for Stable Solid-State Batteries
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Solution Overview
Problem
Existing all-solid-state batteries face a decrease in charge and discharge capacity due to oxidative decomposition of halide solid electrolytes, particularly when elements like chlorine, bromine, and iodine are oxidized, leading to increased internal resistance.
Innovation Solution
A positive electrode material is developed with a surface coating of a solid electrolyte material comprising Li, Ti, and F, where Ti is selected from Ca, Mg, Al, Y, or Zr, enhancing oxidation resistance and ionic conductivity, thereby reducing interfacial resistance and maintaining charge and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If halide solid electrolytes are used in all-solid-state batteries, then ionic conductivity is improved, but oxidative decomposition occurs leading to increased internal resistance and decreased charge-discharge capacity
Solution Approach 1:
A coating layer comprising Li, Ti, M1, and F (where M1 is Ca, Mg, Al, Y, or Zr) is applied to the positive electrode active material surface. This coating acts as an intermediary barrier between the positive electrode and the halide solid electrolyte, preventing direct contact and thus preventing oxidative decomposition of the electrolyte while maintaining ionic conductivity for battery operation.
Solution Approach 2:
The positive electrode structure is designed as a composite system with the coating layer containing specific elements (Li, Ti, M1, F) that combines the benefits of high ionic conductivity with enhanced oxidation resistance. The composite structure integrates the coating material with the positive electrode active material to achieve both functions simultaneously.
2Object-affected harmful factors
If the positive electrode active material is coated with a solid electrolyte material, then oxidation resistance is improved, but interfacial resistance increases
Solution Approach 1:
The coating layer's composition parameters are specifically optimized by incorporating Li, Ti, M1, and F elements in controlled proportions. This parameter optimization ensures the coating provides sufficient oxidation resistance while maintaining appropriate thickness and composition to allow ionic transport, thereby balancing protection with conductivity.
Solution Approach 2:
The coating is applied to coat at least partially the surface of the positive electrode active material, providing localized protection where oxidation occurs most intensely at the interface. The coating's composition and thickness are tailored to the specific interface requirements, ensuring oxidation resistance at the surface while maintaining bulk ionic conductivity.
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 material effectively suppresses oxidative decomposition, enhancing the charge and discharge capacity of batteries by reducing internal resistance and maintaining energy density.
Implementation Method 1
enhancing oxidation resistance and ionic conductivity, thereby reducing interfacial resistance
Implementation Method 2
enhancing oxidation resistance and ionic conductivity, thereby reducing interfacial resistance
Data Source
AI summary
A positive electrode material of the present disclosure includes: a positive electrode active material; a first solid electrolyte material coating at least partially a surface of the positive electrode active material; and a second electrolyte material. The positive electrode active material includes an oxide consisting of Li, Ni, Mn, and O. The first solid electrolyte material includes Li, Ti, M1, and F. The M1 is at least one selected from the group consisting of Ca, Mg, Al, Y, and Zr.