LTO Negative Electrode Heat Treatment to Eliminate Memory Effect
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Solution Overview
Problem
Lithium-titanium-oxide (Li4Ti5O12, LTO) based negative electrode materials for lithium secondary batteries face challenges with low electric conductivity and lithium ion conductivity, leading to a memory effect due to aluminum doping and oxygen vacancies.
Innovation Solution
A method involving primary and secondary heat treatments in air and oxygen atmospheres, respectively, to improve conductivity and reduce oxygen vacancies, eliminating the need for aluminum doping while enhancing electric and lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-titanium-oxide is doped with aluminum to improve electric conductivity and lithium ion conductivity, then conductivity is improved, but memory effect occurs due to aluminum ion interference with lithium ion movement
Solution Approach 1:
The patent removes aluminum doping from the lithium-titanium-oxide composition entirely. Instead of using aluminum to improve conductivity, the invention uses a two-stage heat treatment process to eliminate oxygen vacancies, which are the actual root cause of both the conductivity issues and the memory effect. This extraction of the problematic aluminum component resolves the contradiction by eliminating the source of memory effect while maintaining conductivity through a different mechanism.
Solution Approach 2:
The patent changes the physical and chemical parameters of lithium-titanium-oxide through controlled heat treatment. The first heat treatment at 400-800°C reduces oxygen vacancies to improve conductivity, while the second heat treatment at 600-1000°C in oxygen atmosphere further eliminates remaining oxygen vacancies. This parameter change approach improves conductivity without introducing aluminum, thereby avoiding the memory effect.
2Stability of the object's composition
If lithium-titanium-oxide is used as negative electrode material to achieve great stability, then stability is improved, but electric conductivity and lithium ion conductivity remain low
Solution Approach 1:
The patent applies parameter changes through two-stage heat treatment to modify the physical and chemical properties of lithium-titanium-oxide. The first heat treatment at 400-800°C for 1-10 hours reduces oxygen vacancies, improving conductivity. The second heat treatment at 600-1000°C for 1-10 hours in oxygen atmosphere further eliminates oxygen vacancies. These parameter changes enhance conductivity while preserving the structural stability of LTO.
Solution Approach 2:
The patent creates a composite structure by combining lithium-titanium-oxide with carbon materials (such as acetylene black, graphite, or carbon nanotubes) in the negative electrode. This composite approach improves electric conductivity and lithium ion conductivity through the carbon component while maintaining the stability benefits of LTO, without requiring aluminum doping.
3Reliability
If aluminum doping is applied to improve conductivity, then conductivity is improved, but oxygen vacancies are formed causing memory effect
Solution Approach 1:
The patent extracts and eliminates oxygen vacancies from the lithium-titanium-oxide structure through controlled heat treatment processes. The first heat treatment at 400-800°C begins the reduction of oxygen vacancies, and the second heat treatment at 600-1000°C in oxygen atmosphere completes the elimination. This extraction approach improves conductivity by removing the harmful oxygen vacancies without forming them through aluminum doping.
Solution Approach 2:
The patent substitutes the chemical doping mechanism (aluminum doping) with a thermal processing mechanism (two-stage heat treatment). Instead of using chemical substitution to improve conductivity, the invention uses thermal energy to eliminate oxygen vacancies and improve conductivity through a purely physical/thermal process, thereby avoiding the formation of memory effect.
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 method effectively improves electric and lithium ion conductivity and reduces the memory effect in lithium secondary batteries without using aluminum doping, resulting in a more stable and efficient negative electrode material.
Implementation Method 1
improving electric conductivity and lithium ion conductivity of the base structure by primarily heat-treating the base structure
Implementation Method 2
eliminating an oxygen vacancy present in the primarily heat-treated base structure by secondarily heat-treating the primarily heat-treated base structure
Data Source
AI summary
Provided is a method for producing a negative electrode material for a lithium secondary battery. The method for producing a negative electrode material for a lithium secondary battery may comprise the steps of: preparing a base structure including lithium-titanium-oxide (Li4Ti5O12, LTO); improving the electrical conductivity and lithium ion conductivity of the base structure by primarily heat treating the base structure; and eliminating oxygen vacancies present in the primarily heat-treated base structure by secondarily heat treating the primarily heat-treated base structure.