Lithium Titanate Electrode Doping for High-Rate Discharge
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Solution Overview
Problem
Lithium secondary batteries face limitations in high-rate discharge characteristics, particularly due to the structural changes and ion intercalation/deintercalation processes that affect their energy storage and durability.
Innovation Solution
A negative electrode active material is developed by substituting a portion of lithium in lithium titanate with strontium (Sr) or barium (Ba), enhancing electrical conductivity and thermal stability, which is achieved through a method involving the mixing of lithium salts, titanium precursors, and alkaline earth metal salts followed by heat-treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If lithium titanate is used as negative electrode active material, then structural stability is improved, but electrical conductivity deteriorates
Solution Approach 1:
The patent substitutes lithium ions with alkaline earth metal ions (Sr²⁺, Ba²⁺) in the lithium titanate structure, changing the chemical composition parameters to simultaneously improve electrical conductivity while maintaining structural stability. The substitution ratio is controlled within specific ranges (0.01-0.20 mol fraction) to optimize both properties.
Solution Approach 2:
The patent creates a composite material system by incorporating alkaline earth metals (Sr, Ba) into the lithium titanate structure, forming a doped composite that combines the structural stability of Li4Ti5O12 with the electrical conductivity benefits of alkaline earth metal doping.
2Quantity of substance
If high-capacity silicon-based or tin-based materials are used, then energy density is improved, but structural changes during cycling worsen
Solution Approach 1:
The patent modifies the chemical composition of lithium titanate by substituting lithium with alkaline earth metals, changing the material parameters to achieve better electrical conductivity and high-rate discharge characteristics while maintaining the zero-strain structural advantage.
3Duration of action of stationary object
If lithium titanate is used for repeated charging and discharging, then structural stability is improved, but high-rate discharge characteristics deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of lithium titanate by doping with alkaline earth metals, which improves electrical conductivity and enables better high-rate discharge characteristics while preserving the structural stability needed for long cycle life.
Solution Approach 2:
The improved electrical conductivity from alkaline earth metal doping allows lithium ions to move more rapidly through the structure during high-rate discharge, enabling the material to 'rush through' the discharge process more efficiently without compromising structural integrity.
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 titanate active material improves high-rate discharge characteristics and stability, leading to enhanced power performance and capacity retention in lithium secondary batteries.
Implementation Method 1
a portion of lithium of the lithium titanate is substituted by at least one selected from the group consisting of strontium (Sr), barium (Ba), a mixture thereof and an alloy thereof
Implementation Method 2
heat-treating the mixture
Data Source
AI summary
A negative electrode active material, a method of preparing the negative electrode active material and a lithium secondary battery including the negative electrode active material are disclosed. A negative electrode active material includes a lithium titanate, wherein a portion of lithium of the lithium titanate is substituted by at least one selected from the group consisting of Sr, Ba, a mixture thereof and an alloy thereof, and thus a lithium secondary battery including the negative electrode active material may improve high-rate discharge characteristics.