Mixed Phase Battery Active Material for High Current Stability
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Solution Overview
Problem
Non-aqueous electrolyte batteries using lithium titanium composite oxides as negative electrodes face challenges in achieving high current characteristics due to low electronic and lithium ion conductivity, and the addition of conductive materials like carbonaceous materials can lead to gas generation and performance deterioration.
Innovation Solution
A mixed phase active material comprising lithium titanium composite oxide and nonstoichiometric titanium oxide is sintered together to enhance electronic conductivity and stability, eliminating the need for additional conductive agents and binders, thereby improving large current characteristics and preventing gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbonaceous material is added as conductive agent to lithium titanium composite oxide, then electronic conductivity is improved, but gas generation occurs and battery performance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating nonstoichiometric titanium oxide (TiOx where x<2) into the lithium titanium composite oxide structure. This compositional parameter change inherently provides electronic conductivity without requiring external carbonaceous conductive agents, thereby avoiding gas generation while maintaining improved electronic conductivity.
Solution Approach 2:
The patent creates a composite material system where nonstoichiometric titanium oxide is integrated within the lithium titanium composite oxide matrix. This composite structure combines the high capacity characteristics of lithium titanium composite oxide with the electronic conductivity of nonstoichiometric titanium oxide, eliminating the need for separate conductive agents like carbon black that cause gas generation problems.
2Duration of action of stationary object
If lithium titanium composite oxide is used as negative electrode active material, then cycle characteristics are improved, but large current characteristics deteriorate due to low electronic and lithium ion conductivity
Solution Approach 1:
The patent applies local quality by creating regions of nonstoichiometric titanium oxide within the lithium titanium composite oxide structure. These local nonstoichiometric regions provide enhanced electronic conductivity pathways exactly where needed, while the overall lithium titanium composite oxide structure maintains its excellent cycle characteristics and low volume expansion properties.
Solution Approach 2:
The patent employs a composite material approach where nonstoichiometric titanium oxide phases are embedded within the lithium titanium composite oxide matrix. This composite structure simultaneously achieves excellent cycle characteristics from the lithium titanium composite oxide and improved large current characteristics from the nonstoichiometric titanium oxide's higher electronic conductivity.
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 mixed phase active material enables non-aqueous electrolyte batteries to exhibit enhanced large current characteristics and stability, with reduced gas generation and improved cycle life, maintaining performance even at high temperatures.
Implementation Method 1
A mixed phase active material comprising lithium titanium composite oxide and nonstoichiometric titanium oxide is sintered together to enhance electronic conductivity
Implementation Method 2
A mixed phase active material comprising lithium titanium composite oxide and nonstoichiometric titanium oxide is sintered together
Data Source
AI summary
An active material for a battery includes a mixed phase includes a lithium titanium composite oxide phase and a nonstoichiometric titanium oxide phase. This active material is excellent in lithium absorption/desorption performance, exhibiting high electric potentials in lithium absorption/desorption and high conductivity.