Solid Electrolyte Molten Lithium Cells for Low-Temperature Efficiency
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Solution Overview
Problem
Existing lithium-based molten liquid metal electrode (LME) batteries face challenges with high operating temperatures, leading to maintenance costs, corrosion, safety issues, and low Coulombic efficiencies due to lithium dissolution in molten lithium salts.
Innovation Solution
The use of a solid electrolyte, specifically a lithium ion conductive oxide, phosphate, or sulfide, positioned between a lithium metal or alloy anode and a reactive cathode material, such as Sn—Pb or Bi—Pb alloys, to reduce interfacial impedance and enhance electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If molten lithium salts are used as electrolyte, then battery can operate at high temperature, but Coulombic efficiency decreases due to lithium dissolution
Solution Approach 1:
A solid electrolyte layer is introduced as an intermediary between the molten lithium anode and the cathode. This solid electrolyte prevents lithium dissolution into the molten salt while maintaining ionic conductivity, thereby resolving the contradiction between high-temperature operation and high Coulombic efficiency.
Solution Approach 2:
The electrolyte is changed from liquid molten salt to solid material, fundamentally altering the physical state parameter. This parameter change eliminates lithium dissolution while preserving the battery's ability to operate at elevated temperatures for enhanced safety and reduced viscosity.
2Reliability
If molten lithium salts are used as electrolyte, then battery can conduct ions, but maintenance costs increase due to corrosion and safety issues
Solution Approach 1:
The solid electrolyte acts as a protective intermediary that prevents direct contact between molten lithium and the cathode components, eliminating corrosion issues. This resolves the contradiction by maintaining ionic conductivity while removing the harmful corrosive effects that lead to high maintenance costs.
Solution Approach 2:
The high reactivity and corrosiveness of molten lithium, which normally causes safety issues and maintenance problems, is converted into a benefit by using it only in a contained molten state with a solid electrolyte barrier. The harmful corrosion is eliminated while retaining the beneficial ionic conductivity and low-temperature operation advantages.
3Duration of action of moving object
If molten lithium salts are used as electrolyte, then battery can operate, but hermetic seal becomes difficult to maintain
Solution Approach 1:
The solid electrolyte serves as a stable intermediary layer that does not require complex sealing mechanisms. Its solid state and chemical stability allow for simpler cell construction and easier maintenance of hermetic seals throughout the battery's operational life, resolving the contradiction between operational continuity and sealing complexity.
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
This configuration achieves high Columbic efficiency (up to 99.98%), energy efficiency (up to 84%), and power capability, while reducing operating temperatures and maintaining a hermetic seal, thus addressing the limitations of traditional molten lithium batteries.
Implementation Method 1
a solid electrolyte positioned between the anode and the cathode, wherein the solid electrolyte comprises a lithium ion conductive oxide, a lithium ion conductive phosphate, a lithium ion conductive sulfide
Implementation Method 2
an anode, wherein the anode comprises lithium metal or a lithium alloy; a cathode in spaced relation to the anode, wherein the cathode comprises a cathode material reactive with the anode
Implementation Method 3
a cathode in spaced relation to the anode, wherein the cathode comprises a cathode material reactive with the anode
Data Source
AI summary
Molten lithium electrochemical cells are disclosed. A solid electrolyte separates a molten lithium metal or molten lithium metal alloy from a cathode. The molten lithium cells provide high Coulombic efficiency and energy efficiency at operating temperatures less than 600° C. The cells are useful for stationary energy storage in power grids.