Monoclinic Titanium Dioxide Pore Structure for Battery Efficiency
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Solution Overview
Problem
Nonaqueous electrolyte batteries using spinel type lithium titanate as the negative electrode face challenges with low energy density and reduced first cycle Coulomb efficiency due to the need for high reversible capacity and lithium-diffusibility, which is not adequately addressed by existing titanium oxide compounds like TiO2 with monoclinic structure.
Innovation Solution
The use of monoclinic system titanium dioxide with an average pore diameter ranging from 8 nm to 25 nm and a volume of pores with a diameter of 10 nm or less within 10% to 30% of the total pore volume, along with specific surface area control, enhances lithium-diffusibility and charge-discharge reactions, thereby improving reversible capacity and first cycle Coulomb efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If titanium dioxide is micronized to obtain high reversible capacity, then reversible capacity is improved, but specific surface area increases leading to reduced first cycle Coulomb efficiency
Solution Approach 1:
The patent applies porous materials by controlling the pore structure of titanium dioxide with specific pore diameter (8-25 nm) and pore volume (10-30%). This porous structure allows sufficient lithium ion insertion/extraction sites for high reversible capacity while the controlled pore size limits excessive specific surface area, thereby maintaining high first cycle Coulomb efficiency. The porous structure provides optimal balance between capacity and efficiency.
Solution Approach 2:
The patent applies parameter changes by precisely controlling critical parameters including pore diameter (8-25 nm), pore volume (10-30%), and specific surface area. By optimizing these parameters, the invention achieves both high reversible capacity and high first cycle Coulomb efficiency, resolving the contradiction between quantity of substance and reliability.
2Reliability
If spinel type lithium titanate is used as negative electrode, then safety is improved due to high Li inserting/releasing potential, but energy density decreases
Solution Approach 1:
The patent applies composite materials by combining titanium dioxide with specific pore structure characteristics to create a composite negative electrode material. This composite structure maintains the safety advantages of titanium-based materials (high Li inserting/releasing potential, no dendrite formation) while achieving higher energy density through optimized pore architecture that enables greater reversible capacity.
3Productivity
If pores with diameter of 10 nm or less are increased to improve large-current characteristics, then charge-discharge cycle characteristics are improved, but first cycle Coulomb efficiency is reduced
Solution Approach 1:
The patent applies parameter changes by establishing an optimal range for pore diameter (8-25 nm) and pore volume (10-30%). This parameter optimization allows the material to achieve improved large-current characteristics and charge-discharge cycle characteristics while maintaining high first cycle Coulomb efficiency, avoiding the harmful effect of excessive small pores.
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 approach results in a high discharge capacity and improved first cycle Coulomb efficiency for nonaqueous electrolyte batteries, balancing lithium-diffusibility and powder strength while minimizing electrolyte decomposition, leading to enhanced battery performance.
Implementation Method 1
enhances lithium-diffusibility and charge-discharge reactions
Implementation Method 2
enhances lithium-diffusibility and charge-discharge reactions
Data Source
AI summary
According to one embodiment, a negative electrode active material includes monoclinic system titanium dioxide having an average pore diameter falling within a range of 8 nm to 25 nm. A volume of pores having a diameter of 10 nm or less falls within a range of 10% to 30% of a total pore volume.