Lithium Niobate Coating for Solid Electrode Interface Resistance
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Solution Overview
Problem
The challenge in all-solid-state lithium ion batteries is the increased interface resistance between the positive electrode active material and the solid electrolyte, which deteriorates battery performance, and existing methods face issues with ammonia and hydrogen peroxide excess leading to chemical damage, corrosion, and storage instability.
Innovation Solution
A solution containing lithium and a niobium or titanium complex is developed, with a peroxo complex and stability improvers like citric acid, where ammonia and hydrogen peroxide are managed to minimize residual amounts, reducing corrosiveness and improving storage stability, forming a coating layer that enhances battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte is used in all-solid-state lithium ion batteries, then safety is improved by eliminating flammability, but interface resistance increases due to lack of penetration mechanism between active material particles
Solution Approach 1:
The patent applies preliminary action by pre-coating the surface of positive electrode active material particles with lithium niobate before assembling the battery. This advance surface treatment creates a favorable interface condition that reduces resistance when the solid electrolyte is later introduced, solving the penetration issue without compromising safety.
Solution Approach 2:
Lithium niobate coating serves as an intermediary layer between the positive electrode active material and the solid electrolyte. This intermediate coating improves interfacial contact and reduces resistance, facilitating lithium ion transport while maintaining the safety benefits of the solid electrolyte system.
2Object-affected harmful factors
If metal alkoxide and alcohol solution are used to coat the active material surface, then interface resistance is reduced, but storage stability deteriorates due to precipitate formation
Solution Approach 1:
The patent changes the chemical parameters of the coating solution by replacing traditional alcohol-based metal alkoxide solutions with a water-based system using niobium complex, citric acid, and hydrogen peroxide. This parameter change eliminates precipitate formation while maintaining the ability to form effective lithium niobate coating, thus improving storage stability without sacrificing interface resistance reduction.
Solution Approach 2:
The patent uses a stable, shelf-life-friendly solution formulation that can be stored for extended periods without degradation. The water-based niobium complex solution with citric acid stabilizer replaces short-lived alcohol-based metal alkoxide solutions, enabling long-term storage while maintaining coating effectiveness.
3Stability of the object's composition
If excessive ammonia is present in the coating solution, then niobium complex stability is improved, but chemical damage and corrosion increase
Solution Approach 1:
The patent optimizes the ammonia concentration parameter to a specific range (0.1-10 mmol/L) that provides sufficient niobium complex stability while minimizing chemical damage and corrosion. This precise parameter control balances the competing requirements of solution stability and material safety.
Solution Approach 2:
The patent incorporates citric acid as a stability improver that provides feedback control for the niobium complex formation. The citric acid monitors and adjusts the complexation equilibrium, ensuring that ammonia remains within the optimal range for stability without exceeding levels that cause corrosion, thus providing self-regulating protection.
4Quantity of substance
If excessive hydrogen peroxide is present in the coating solution, then complex formation is enhanced, but corrosiveness and handling difficulty increase
Solution Approach 1:
The patent controls hydrogen peroxide concentration within an optimized range (1-50 mmol/L relative to niobium) that ensures sufficient complex formation while minimizing corrosiveness. This parameter optimization balances the need for effective coating formation with safe handling and storage characteristics.
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 solution achieves excellent battery characteristics with improved handling and storage stability, reducing interface resistance and maintaining lithium ion exchange efficiency, thus enhancing the performance of secondary batteries.
Implementation Method 1
a reaction of the positive electrode active material and the solid electrolyte to form a high resistance portion on the surface of the positive electrode active material
Implementation Method 2
resistance generated when lithium ions migrate at an interface between the positive electrode active material and the solid electrolyte
Data Source
Figure 1~2
Figure 3~3(c)
Figure 4
AI summary
There is provided a solution containing lithium and at least one of a niobium complex and a titanium complex, suppresses corrosiveness, excellent in storage stability, and suitable for forming a coating layer capable of improving battery characteristics of an active material, and a related technique, which is the solution containing lithium, at least one of a niobium complex and a titanium complex, and ammonia, wherein an amount of the ammonia in the solution is 1 mass% or less.