Bronze-Type Titanium Oxide Electrode for Lithium Ion Battery
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Solution Overview
Problem
Lithium ion secondary batteries using bronze-type titanium oxide compounds face issues with low initial charge/discharge efficiency due to their large specific surface area and reactivity with electrolytic solutions, and modifying the composition to improve efficiency often results in decreased capacity.
Innovation Solution
A titanium oxide compound with controlled particle shape, specifically bronze-type titanium oxide containing calcium and/or silicon in certain mass percentages, is used as an electrode active material, reducing specific surface area and improving coatability without altering sintering conditions, and is applied as a positive or negative electrode in lithium ion secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bronze-type titanium oxide compound is synthesized from K2Ti4O9, then the negative electrode potential is raised to reduce metal lithium crystal deposition, but the specific surface area increases causing low initial charge/discharge efficiency
Solution Approach 1:
The invention changes the chemical composition parameters by adding calcium (0.005-2.5 mass%) and/or silicon (0.15-0.55 mass%) to the bronze-type titanium oxide compound. This compositional modification alters the crystal growth behavior to produce plate-like particles instead of needle-like particles, thereby reducing specific surface area and improving initial charge/discharge efficiency while maintaining the high potential characteristics
Solution Approach 2:
The invention creates a composite material system by incorporating calcium and/or silicon into the bronze-type titanium oxide structure. This composite approach modifies the physical and chemical properties of the base material, achieving both low specific surface area and high initial charge/discharge efficiency while maintaining the desired electrode potential
2Productivity
If isotropic bronze-type titanium oxide compound is manufactured from sodium compound and titanium oxide, then initial charge/discharge efficiency is improved, but the initial charge capacity decreases to approximately 170 mAh/g
Solution Approach 1:
The invention optimizes the chemical composition parameters by precisely controlling the content of calcium (0.005-2.5 mass%) and silicon (0.15-0.55 mass%). This parameter optimization achieves the right balance between improving initial charge/discharge efficiency and maintaining high initial charge capacity (335 mAh/g or higher), avoiding the capacity loss experienced with sodium-based isotropic compounds
3Quantity of substance
If needle crystal structure is formed, then specific surface area increases improving reactivity, but the electrode is apt to react with electrolytic solution reducing efficiency
Solution Approach 1:
The invention transforms the crystal morphology from needle-like (high aspect ratio) to plate-like (low aspect ratio) by modifying the composition with calcium and/or silicon. This morphological asymmetry change reduces the specific surface area while maintaining adequate reactivity, thereby minimizing harmful reactions with the electrolytic solution and improving overall electrode efficiency
Data Source
AI summary
A titanium oxide compound according to the present invention comprises bronze-type titanium oxide or titanium oxide mainly composed of bronze-type titanium oxide, and contains calcium and/or silicon. The titanium oxide compound contains 0.005 to 2.5 mass % inclusive of calcium or 0.15 to 0.55 mass % inclusive of silicon, or contains 0.005 to 1.2 mass % inclusive of calcium and 0.15 to 0.2 mass % inclusive of silicon, or contains 0.005 to 0.1 mass % inclusive of calcium and 0.15 to 0.5 mass % inclusive of silicon.