Titanium Oxide Anode Composition for Fast-Charging Li-Ion Batteries
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Solution Overview
Problem
Lithium ion secondary batteries face limitations in capacity and electron conductivity, particularly with titanium oxide-based negative electrodes, which hinder high input and output characteristics.
Innovation Solution
Incorporating titanium oxide particles represented by the formula H2Ti12O25 with 0.3-5.0 weight percent single wall carbon nanotubes into the negative electrode to enhance electron conductivity and improve input and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li4Ti5O12 is used as negative electrode material to avoid lithium deposition, then discharge and charge potential is improved (1.5V vs Li/Li+), but electron conductivity is low requiring conductive agents which decrease capacity
Solution Approach 1:
The patent uses a composite structure where Li4Ti5O12 particles are combined with conductive carbon materials (graphite, carbon black, or conductive polymer) to create a negative electrode that maintains both high discharge potential (avoiding lithium deposition) and sufficient electron conductivity. The conductive agent forms a network around the Li4Ti5O12 particles, ensuring electron transport while the low amount used (1-20 wt%) minimizes capacity loss.
2Productivity
If high input charging is implemented to achieve short charging time, then charging speed is improved, but high overvoltage causes lithium deposition on graphite negative electrodes
Solution Approach 1:
The patent changes the electrochemical potential parameter of the negative electrode by using Li4Ti5O12 with a discharge potential of 1.5V vs Li/Li+, which is significantly higher than graphite's potential. This parameter change allows the battery to accept high input charging currents without causing lithium deposition, as the higher potential prevents the thermodynamic conditions for lithium plating on the negative electrode.
3Power
If conductive agents are added to improve electron conductivity of Li4Ti5O12, then electron conductivity is improved, but capacity is extremely decreased
Solution Approach 1:
The patent applies local quality by concentrating the conductive agent specifically at the particle surfaces and inter-particle regions of Li4Ti5O12, rather than uniformly mixing throughout the electrode. The conductive carbon materials form localized conductive networks and coatings on the Li4Ti5O12 particle surfaces, providing electron conductivity pathways exactly where needed for electron transport to and from the active material, while minimizing the overall amount of conductive agent required.
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 combination of H2Ti12O25 with single wall carbon nanotubes improves electron conductivity, leading to enhanced input and output characteristics and increased capacity without compromising mechanical strength.
Implementation Method 1
The negative electrode contains titanium oxide particles that are particles of titanium oxide represented by general formula H2Ti12O25, a binder, and 0.3-5.0 weight percent of single wall carbon nanotubes with respect to the titanium oxide
Data Source
AI summary
Disclosed is a nonaqueous electrolyte secondary battery having improved electron conductivity of an electrode and improved input and output characteristics. The nonaqueous electrolyte secondary battery includes a positive electrode containing a lithium-containing transition metal composite oxide as an active material, a negative electrode, and a nonaqueous electrolyte. The negative electrode contains titanium oxide particles that are particles of titanium oxide represented by general formula H2Ti12O25, a binder, and 0.3-5.0 weight percent of single wall carbon nanotubes with respect to the titanium oxide. The titanium oxide particles have a secondary particle size D50 of 1 to 15 μm and a secondary particle size D90 of 50 μm or less.