Li1+xTM1-xO2 Electrode Material Process for Cycling Stability
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Solution Overview
Problem
Lithium-ion battery electrode active materials face challenges with reduced cycle life and capacity loss due to high Li2CO3 content, which affects the stability and performance of lithium-ion batteries.
Innovation Solution
A process for producing an electrode active material with the formula Li1-xTM1-xO2, where TM is a combination of Mn, Co, and Ni, with at least 60 mole-% Ni, by mixing a mixed oxide or oxyhydroxide of Mn, Co, and Ni with a lithium compound and an oxide or hydroxide of Al, Ti, or W, followed by heat treatment at 700-1000°C to minimize Li2CO3 content and enhance cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithium carbonate is used as starting material or if basic electrode active material is employed, then the manufacturing process is simplified and cost-effective, but Li2CO3 accumulates during thermal treatment which impairs cycling stability and area specific resistance
Solution Approach 1:
The patent extracts and removes Li2CO3 from the reaction mixture during thermal treatment by maintaining a controlled oxygen partial pressure (0.1-10 bar) that shifts the equilibrium Li2CO3 ⇌ Li2O + CO2 to the right, causing CO2 to escape and Li2O to remain as a useful product that enhances cycling stability
Solution Approach 2:
The patent changes the oxygen partial pressure parameter during thermal treatment to control the decomposition of Li2CO3. By operating at elevated oxygen pressures (0.1-10 bar), the process prevents harmful side reactions while allowing controlled decomposition of Li2CO3 to Li2O, which improves cycling stability without compromising manufacturing simplicity
2Ease of manufacture
If lithium carbonate is used as starting material, then the process is cost-effective and easy to implement, but Li2CO3 uptake of CO2 occurs during thermal treatment which adversely affects area specific resistance
Solution Approach 1:
The patent changes the oxygen partial pressure parameter to control the chemical equilibrium of Li2CO3 decomposition. By maintaining oxygen pressures of 0.1-10 bar during thermal treatment, the process prevents CO2 uptake by basic materials while allowing controlled decomposition of Li2CO3 to Li2O, thereby maintaining cost-effectiveness while reducing area specific resistance
3Quantity of substance
If high nickel content (at least 60 mole-%) is used in TM, then charge density and specific energy are improved, but cycling stability and capacity loss are adversely affected
Solution Approach 1:
The patent creates a composite material system combining high-nickel TM (at least 60 mole-%) with Li2O generated in situ from Li2CO3 decomposition and dopant oxides (Al2O3, TiO2, or WO3). This composite structure leverages the high charge density of nickel while the Li2O and dopant oxides provide structural stability, improving cycling stability without sacrificing charge density
Solution Approach 2:
The patent converts the harmful effect of Li2CO3 (which normally impairs cycling stability) into a beneficial source of Li2O by controlling thermal treatment conditions. The Li2O generated from Li2CO3 decomposition, combined with dopant oxides, forms a stable composite structure that enhances cycling stability while maintaining the high charge density provided by nickel
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 process results in electrode active materials with improved cycling stability and reduced Li2CO3 content, leading to enhanced performance and longevity of lithium-ion batteries.
Implementation Method 1
During the thermal treatment a solid state reaction takes place, and the electrode active material is formed
Implementation Method 2
In cases hydroxides or carbonates are used as precursors the solid state reaction follows a removal of water or carbon dioxide
Data Source
AI summary
Process for making an electrode active material according to general formulaLi1+χΤΜ1-χO2, wherein TM is a combination of Mn, Co and Ni in combination with at least one more metal selected from Al, Ti, and W, wherein at least 60 mole-% of TM is Ni, the percentage referring to the sum of Ni, Co and Mn, and x is in the range of from zero to 0.2, said process comprising the following steps: (a) mixing (A) a mixed oxide or oxyhydroxide of Mn, Co and Ni, (B) at least one lithium compound selected from lithium hydroxide, lithium oxide and lithium carbonate, and (C) an oxide, hydroxide or oxyhydroxide of Al, Ti or W, (b) Subjecting said mixture to heat treatment at a temperature in the range of from 700 to 1000°C.