Titanic Acid Solid Electrolyte With Cation-Substituted Titanate Layers
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Solution Overview
Problem
Oxide-based solid electrolyte materials for lithium-ion secondary batteries pose safety concerns due to potential hydrogen sulfide production and high production costs associated with rare earth elements, while sulfide-based materials have high reactivity with moisture.
Innovation Solution
Development of a titanic acid-based solid electrolyte material with a lepidocrocite titanate structure, where lithium ions are intercalated between host layers, and titanium sites are partially substituted by cations with +1 to +3 valences, eliminating the risk of hydrogen sulfide production and rare earth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide-based solid electrolyte materials are used, then safety is improved compared to liquid electrolytes, but production cost increases due to rare earth usage
Solution Approach 1:
The patent replaces expensive rare earth-based oxide materials with a cheaper alternative based on common elements (titanium, lithium, oxygen). The use of abundant materials like titanium instead of rare earth elements directly addresses the cost issue while maintaining the solid electrolyte safety advantages.
Solution Approach 2:
The patent changes the chemical composition parameters by substituting rare earth elements with titanium-based compounds. Specifically, it uses lithium titanate (Li4Ti5O12) and related compounds where titanium replaces the rare earth metal sites, fundamentally altering the material composition to achieve both cost reduction and maintained safety.
2Reliability
If sulfide-based solid electrolyte materials are used, then lithium-ion conductivity is improved, but safety deteriorates due to high reactivity with moisture producing hydrogen sulfide
Solution Approach 1:
The patent avoids using sulfide-based materials that produce harmful hydrogen sulfide. Instead, it employs oxide-based lithium titanate materials that are chemically stable and do not generate toxic gases upon contact with moisture, eliminating the safety hazard while providing a cost-effective alternative.
Solution Approach 2:
The patent creates an inherently stable and inert chemical environment by using oxide-based materials with strong Ti-O bonds. This chemical inertness prevents reactions with moisture and eliminates hydrogen sulfide production, providing a safe operating environment without requiring additional protective measures.
3Reliability
If sulfur is doped into oxide-based solid electrolyte material to improve lithium-ion conductivity, then conductivity is improved, but safety deteriorates due to potential hydrogen sulfide production
Solution Approach 1:
The patent achieves improved lithium-ion conductivity through structural design and cation substitution in lithium titanate rather than sulfur doping. It uses magnesium, calcium, or other alkaline earth metal substitutions at titanium sites, which maintain chemical stability and avoid hydrogen sulfide generation while providing the desired conductivity enhancement.
Solution Approach 2:
Instead of using sulfur doping that creates potential harm through hydrogen sulfide production, the patent converts the conductivity improvement goal into a beneficial outcome through alternative mechanisms - specifically, controlled cation substitution and defect engineering in the lithium titanate structure that enhances ion transport without introducing toxic elements.
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 titanic acid-based solid electrolyte material achieves good lithium-ion conductivity and enhanced safety, enabling the production of high-power batteries without the risks of hydrogen sulfide formation or rare earth costs.
Implementation Method 1
lithium ions are intercalated in interlayers between the host layers
Implementation Method 2
titanium sites in the host layers being partially substituted by cations with valences of +1 to +3
Data Source
AI summary
Provided is a titanic acid-based solid electrolyte material free from risk of production of hydrogen sulfide, free of rare earth, and having good lithium-ion conductivity. The titanic acid-based solid electrolyte material is made of a lepidocrocite titanate having a structure in which a plurality of host layers are laid one on top of another, the host layer being formed so that octahedra each formed of a titanium atom coordinated with six oxygen atoms are two-dimensionally chained while sharing ridges, and lithium ions are intercalated in interlayers between the host layers, and titanium sites in the host layers are partially substituted by cations with valences of +1 to +3.