Monoclinic Beta Titanium Complex Oxide Negative Electrode for Battery Voltage Variation
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Solution Overview
Problem
Nonaqueous electrolyte batteries using lithium iron phosphate as the positive electrode active material and lithium titanate as the negative electrode material face challenges in detecting the state of discharge due to minimal variation in battery voltage during discharging, making it difficult to determine the depth of discharge.
Innovation Solution
Incorporating monoclinic β-type titanium complex oxide as the negative electrode active material, along with lithium titanate, and using a chain ether-based organic solvent in the electrolyte, which allows for a varying discharge curve and improved cycle and output performances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium iron phosphate and lithium titanate are used as positive and negative electrode active materials, then cycle performance and safety are improved, but battery voltage variation during discharging becomes small making discharge state detection difficult
Solution Approach 1:
The patent changes the chemical composition parameter of the negative electrode active material by introducing a monoclinic β-type titanium complex oxide with specific crystal structure parameters. This material has a different electrochemical potential characteristics compared to conventional lithium titanate, resulting in increased battery voltage variation during discharge while maintaining the stable cycle performance and safety benefits of the lithium iron phosphate-lithium titanate system.
2Object-affected harmful factors
If lithium iron phosphate and lithium titanate are used as positive and negative electrode active materials, then safety is improved, but battery voltage variation during discharging becomes small making discharge state detection difficult
Solution Approach 1:
The patent creates a composite negative electrode active material system comprising lithium titanate and monoclinic β-type titanium complex oxide. This composite material combines the safety advantages of lithium titanate (zero strain during charge-discharge) with the voltage variation characteristics of monoclinic β-type titanium complex oxide, enabling both safe operation and accurate discharge state detection through increased voltage variation.
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
Enables easy detection of the discharge state and enhances the battery's cycle and output performances by varying the battery voltage with the depth of discharge, while maintaining stable cycle and output performances.
Implementation Method 1
lithium iron phosphate having an olivine structure has a stable crystal structure and has a lithium ion-insertion/extraction potential as relatively low as about 3.4 V (vs. Li/Li+)
Implementation Method 2
The nonaqueous electrolyte comprises an organic solvent
Data Source
AI summary
According to one embodiment, a nonaqueous electrolyte battery is provided. The battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode includes lithium iron phosphate having an olivine structure as positive electrode active material. The negative electrode includes lithium titanate having a spinel structure and a monoclinic β-type titanium complex oxide as a negative electrode active material.