Lithium Titanium Complex Oxide Conductivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium titanium complex oxide materials, such as Li4Ti5O12, used in lithium ion secondary batteries have low electronic conductivity, leading to inadequate output characteristics and discharge capacity, especially at high loads.
Innovation Solution
Substituting a portion of the Ti element in Li4Ti5O12 with Mn, V, or B to form lithium titanium complex oxides like Li4Ti5-x-yMnxBzO12 or Li4Ti5-x-yMnVzO12, which improves electronic conductivity and increases primary particle size, enhancing output characteristics and capacity density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li4Ti5O12 is used as negative electrode active material, then the battery can be used practically with stable structure, but the electronic conductivity is low leading to poor output characteristics
Solution Approach 1:
The patent applies parameter changes by substituting Ti elements with transition metal elements (V, Nb, Mo, P) to alter the electronic conductivity parameter of Li4Ti5O12. This substitution changes the chemical composition parameters while maintaining the spinel crystalline structure, thereby improving output characteristics without sacrificing storage stability.
Solution Approach 2:
The patent creates composite materials by combining Li4Ti5O12 with transition metal elements to form substituted lithium titanium complex oxides. These composite materials exhibit both the structural stability of Li4Ti5O12 and the enhanced electronic conductivity provided by the transition metal substitutions, resolving the contradiction between reliability and power.
2Power
If Ti element is substituted with transition metal elements to improve electronic conductivity, then output characteristics improve, but discharge capacity at high loads becomes insufficient (83% or less than at low loads)
Solution Approach 1:
The patent optimizes the substitution ratio parameters of transition metal elements to achieve a balance between electronic conductivity and discharge capacity. By carefully controlling the amount of substitution (not excessive substitution), the patent maintains sufficient discharge capacity at high loads while still improving output characteristics.
Solution Approach 2:
The patent applies local quality by selectively substituting only a portion of Ti elements with transition metal elements, rather than complete substitution. This partial substitution creates local regions with enhanced conductivity while preserving the overall structure and capacity characteristics of the original Li4Ti5O12.
3Quantity of substance
If primary particle size is increased to improve capacity density, then electrode capacity density increases, but electronic conductivity may deteriorate due to larger particle size
Solution Approach 1:
The patent changes the particle size parameter to increase primary particle size while simultaneously using transition metal substitution to maintain electronic conductivity. The transition metal elements compensate for the conductivity loss that would normally occur with larger particle size, allowing both capacity density and conductivity to be optimized.
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 modified lithium titanium complex oxides exhibit improved electronic conductivity and increased primary particle size, resulting in lithium ion secondary batteries with high output characteristics and capacity density, effectively addressing the limitations of conventional materials.
Implementation Method 1
substituting a portion of Ti element of Li 4 Ti 5 O 12 with Mn element, V element, or B element... substituting a portion of Ti element with a different element selected from V element, Nb element, Mo element and P element
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A negative electrode active material for a lithium ion secondary battery contains a lithium titanium complex oxide having a composition expressed as Li4Ti5-xMnxO12 (where 0<x≤0.3), Li4Ti5-x-yMnxVyO12 (where 0<x≤0.3, 0<y≤0.05), or Li4Ti5-x-zMnxBzO12 (where 0<x≤0.3, 0<z≤0.3).