Lithium Phosphate Solid Electrolyte Coatings for Stable Li-Metal Batteries
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Solution Overview
Problem
Current lithium-ion batteries face safety risks due to flammable organic solvents in their electrolytes and stability issues when in contact with lithium metal anodes, limiting their use in large-scale energy storage.
Innovation Solution
Development of novel lithium phosphate derivative compounds and their incorporation into solid-state lithium ion electrolytes and electrode coating layers, which exhibit high Li+ conductivity, low activation energy, and stability against electrochemical degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flammable organic liquid electrolyte is used in Li-ion batteries, then good Li+ conductivity is achieved, but safety risk increases due to flammability
Solution Approach 1:
The patent transitions the electrolyte from liquid phase to solid phase by using lithium phosphate derivative compounds. This phase transition eliminates the flammability issue inherent in liquid organic electrolytes while maintaining Li+ conductivity through the solid state material structure.
Solution Approach 2:
The patent employs composite material design by combining lithium phosphate derivatives with other materials to create solid electrolytes that achieve both high Li+ conductivity and enhanced safety. The composite structure allows optimization of both conductive pathways and structural stability.
2Reliability
If conventional solid Li-ion conductors are used, then safety is improved by replacing liquid electrolyte, but Li+ conductivity is insufficient compared to liquid phase electrolyte
Solution Approach 1:
The patent optimizes the chemical composition parameters of lithium phosphate derivatives by controlling ratios of Li, P, and O atoms, along with doping elements. This parameter optimization enables the solid electrolyte to achieve Li+ conductivity levels comparable to liquid electrolytes while maintaining the safety advantages of solid state.
3Power
If lithium metal anode is used to achieve high energy density, then battery performance is improved, but dendritic lithium metal structures form over repeated cycles causing safety issues
Solution Approach 1:
The solid lithium phosphate derivative electrolyte acts as an intermediary layer between the lithium metal anode and cathode. This intermediary solid electrolyte prevents direct contact and electron transport that would lead to dendrite formation, while still allowing Li+ ion transport for high energy density operation.
4Reliability
If solid Li-ion conductor is used to block electron transport between electrodes, then safety is improved, but activation energy for Li+ migration must be low for use over range of operation temperatures
Solution Approach 1:
The patent adjusts the structural and compositional parameters of the lithium phosphate derivative to optimize the energy landscape for Li+ migration. By controlling the crystal structure and ionic pathways, the material achieves low activation energy for Li+ transport while maintaining electrochemical stability across temperature ranges.
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 solution achieves lithium ion conductivity ranging from 10−2 to 10 mS/cm at 300K, with activation energies between 0.21 to 0.31 eV, addressing safety concerns and enhancing the performance and stability of lithium batteries.
Implementation Method 1
A primary function of the solid Li-conductive phase, usually called solid Li-ion conductor or solid state electrolyte, is to conduct Li+ ions from the anode side to the cathode side during discharge and from the cathode side to the anode side during charge
Data Source
AI summary
Electrodes for a solid-state lithium-ion battery are provided. The electrodes have an active material layer containing or coated with electrolytes of lithium phosphate derivative compounds which contain an anionic framework capable of conducting lithium ions. Materials of specific formulae are provided and methods to alter the composite materials with inclusion of aliovalent ions shown. Lithium batteries containing the electrodes are also provided.