Zr-Doped Lithium Titanate Anode Coating for Stable High-Rate Output
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Solution Overview
Problem
Existing lithium titanium oxide materials do not meet the high output requirements for 12V or 48V system applications in lithium secondary batteries, particularly in micro Hybrid Electric Vehicles, due to structural characteristics that cause varying resistance and kinetic effects during charging and discharging.
Innovation Solution
A negative electrode active material comprising lithium titanium-based composite particles with Zr doping and an aluminum and sulfur containing compound coating on the surface of lithium titanium oxide, specifically Al2(SO4)3 or Al2S3, to form an inter-diffusion layer that prevents lithium ions from occupying the 8a site, thereby minimizing resistance changes during high-rate intercalation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium titanium oxide is used as negative electrode material, then high output characteristics are expected, but resistance increases during charging and discharging due to kinetic effects
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core is lithium titanium oxide particles and the outer shell is a carbon coating layer. This allows different regions of the material to have different functions: the core provides high output characteristics while the shell reduces resistance increase during charging/discharging. The carbon coating layer specifically addresses the resistance stability issue without compromising the power output of the lithium titanium oxide core.
Solution Approach 2:
The patent uses composite materials by combining lithium titanium oxide with a carbon coating layer to create a core-shell structured composite. This composite structure integrates the high power density of lithium titanium oxide with the electrical conductivity and structural stability of carbon, thereby achieving both high output characteristics and reduced resistance increase during operation.
2Speed
If lithium titanium oxide is used to achieve fast charge and discharge, then 20C or above charge rate is possible, but existing lithium titanium oxide cannot satisfy the output requirement
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical parameters of lithium titanium oxide through carbon coating. The carbon coating changes the electrical conductivity parameter and the surface properties of the lithium titanium oxide particles, enabling faster charge rates (20C or above) while maintaining the required power output for high-performance battery applications.
3Productivity
If high rate intercalation is performed, then fast charging is achieved, but kinetic effects cause varying resistance and non-uniform charge distribution
Solution Approach 1:
The patent applies beforehand cushioning by pre-coating the lithium titanium oxide particles with carbon before they undergo high-rate intercalation during charging. This carbon coating acts as a protective layer that cushions against the kinetic effects that would otherwise cause resistance variations and non-uniform charge distribution. The coating is applied in advance to prevent the harmful effects during the fast charging process.
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 composite material achieves uniform low resistance irrespective of charge direction and rate, enabling its use in 12V or 48V secondary battery systems with minimal resistance increase, suitable for high-output applications like micro hybrid batteries.
Implementation Method 1
Zr doped into the lithium titanium oxide
Implementation Method 2
an aluminum and sulfur containing compound coated on a surface of the lithium titanium oxide
Implementation Method 3
to form an inter-diffusion layer that prevents lithium ions from occupying the 8a site
Data Source
AI summary
A negative electrode active material for a secondary battery and a lithium secondary battery including the same. The negative electrode active material for a secondary battery, includes lithium titanium-based composite particles comprising: a lithium titanium oxide represented by LixTiyOz, wherein x, y and z satisfy 0.1≤x≤4, 1≤y≤5 and 2≤z≤12, Zr doped into the lithium titanium oxide; and an aluminum and sulfur containing compound coated on a surface of the lithium titanium oxide. The aluminum and sulfur containing compound is present in an amount of 0.4 mM to 0.9 mM based on 1M lithium titanium oxide.