Lithium Titanium Oxide Anode Material Residual Lithium Control
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Solution Overview
Problem
Lithium titanium oxide-based negative electrode materials for lithium secondary batteries face challenges in high residual lithium levels, leading to potential safety issues like battery expansion and reduced capacity, especially when stored at high temperatures, due to the generation of gas and low initial charge and discharge efficiency.
Innovation Solution
A method of preparing lithium titanium-based active materials by controlling the sintering temperature and time, and the molar ratio of lithium to titanium, to limit the residual lithium to 2,000 ppm or less, thereby reducing gas generation and maintaining high rate capability, involves mixing lithium and titanium precursors and sintering them in a specific temperature range to form lithium titanium oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium titanium oxide is used as negative electrode material, then safety is improved and initial charge-discharge efficiency is improved, but residual lithium remains high causing gas generation and battery expansion
Solution Approach 1:
The patent applies parameter changes by precisely controlling the sintering temperature (900-1100°C) and time (2-12 hours) to optimize the lithium titanium oxide synthesis process. This controlled parameter adjustment reduces residual lithium content while maintaining the material's safety advantages and initial charge-discharge efficiency above 95%.
Solution Approach 2:
The patent converts the harmful effect of residual lithium into a beneficial outcome by using controlled sintering conditions that transform excess lithium into a manageable parameter. The sintering process converts potential harmful residual lithium into a controlled amount that can be precisely managed through process parameters, turning a safety risk into a controllable variable.
2Object-generated harmful factors
If sintering temperature and time are increased to reduce residual lithium, then gas generation is reduced, but discharge capacity and rate capability may be reduced
Solution Approach 1:
The patent employs parameter changes by establishing optimal sintering conditions in the range of 900-1100°C for 2-12 hours. This specific parameter window achieves the dual benefit of reducing residual lithium content while preserving discharge capacity and rate capability, avoiding the trade-off between lithium reduction and performance maintenance.
Solution Approach 2:
The patent applies partial action by using moderate sintering conditions rather than extreme temperatures or prolonged times. The sintering process is optimized to achieve sufficient lithium reduction without excessive treatment that would damage the material structure and reduce discharge capacity, finding the optimal middle ground.
3Quantity of substance
If carbon-based material is used as negative electrode, then capacity per volume is improved, but irreversible capacity is high reducing initial charge-discharge efficiency
Solution Approach 1:
The patent uses composite materials approach by creating lithium titanium oxide with optimized crystalline structure and morphology. This composite structure combines the high capacity per volume advantage with low irreversible capacity, achieving both high density and high initial charge-discharge efficiency above 95% through material structure optimization.
4Use of energy by moving object
If lithium metal is used as negative electrode, then energy density is improved, but dendrites are generated causing safety risks
Solution Approach 1:
The patent converts the safety risk of dendrite formation into a beneficial outcome by using lithium titanium oxide that prevents dendrite generation while maintaining high energy density. The material's unique structure transforms the potential harm of lithium reactivity into a safety advantage, eliminating dendrites while preserving energy storage capability.
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
This approach significantly reduces the thickness expansion rate and gas generation, while maintaining excellent rate capability and discharge capacity, ensuring battery safety and performance even at high temperatures.
Implementation Method 1
sintering the precursor mixture to prepare a lithium titanium-based active material including a lithium titanium oxide
Data Source
AI summary
A method of preparing a negative electrode active material of the present invention includes mixing a lithium precursor and a titanium precursor, and sintering the precursor mixture to prepare a lithium titanium-based active material including a lithium titanium oxide, wherein a residual amount of lithium in the lithium titanium-based active material is 2,000 ppm or less based on a total amount of the lithium titanium-based active material. The preparation method allows the residual amount of lithium to be 2,000 ppm or less in a range, in which rate capability is not significantly reduced, by appropriately controlling sintering temperature, wherein the method may provide a lithium secondary battery, in which an amount of gas generated is extremely small even if stored at high temperature, a thickness expansion rate is consequently considerably low, and, simultaneously, the rate capability is also excellent.