Overlithiated Layered Oxide Cathode Stabilizing High Voltage Cycle Life
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Solution Overview
Problem
Lithium rechargeable batteries face limitations in energy density and cycle-life characteristics due to structural instability and voltage drop when using traditional positive active materials like LiCoO2, especially at high voltages.
Innovation Solution
The development of an overlithiated layered oxide (OLO) positive active material, represented by Chemical Formulas LiaNibCocMndMeO2 and LiaNibCocMndMeO2-fM′f, doped with cation and anion elements such as V, Ga, Zr, Mg, Al, Ti, Cr, Fe, W, Mo, Si, or their combinations, which stabilizes the structure through oxidation reduction reactions, enhancing charge and discharge capacity and suppressing voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LiCoO2 is used as positive active material, then high energy density is achieved, but reversible capacity is limited to less than or equal to 200 mAh/g and structural instability occurs during charge
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of LiCoO2 through doping with elements such as Al, Ga, In, Ti, Zr, Hf, Si, Ge, Sn, Pb, B, P, or As at concentrations of 0.01-5 mol%. This compositional parameter modification enables the material to achieve reversible capacity greater than 200 mAh/g while maintaining structural stability during charge, thus resolving the contradiction between energy density and structural reliability
Solution Approach 2:
The patent creates composite materials by combining LiCoO2 with dopant elements to form doped LiCoO2 compounds. These composite structures integrate the high energy density characteristics of LiCoO2 with the structural stability provided by the dopant elements, achieving both high reversible capacity (>200 mAh/g) and structural reliability during charging operations
2Use of energy by moving object
If overlithiated layered oxide (OLO) is used as positive active material, then high charge and discharge capacity at high voltage is achieved, but capacity deterioration and voltage drop occur during repeated charge and discharge
Solution Approach 1:
The patent modifies the compositional parameters of OLO by incorporating cation elements (Li, Na, K, Ag, Cu, Au, In, Ga, Al, B, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and anion elements (F, Cl, Br, I, S, Se, Te) in controlled amounts. This parameter optimization enables the material to maintain both high charge/discharge capacity and improved cycle life by stabilizing the crystal structure against degradation during repeated cycling
Solution Approach 2:
The patent employs sacrificial dopant elements that can undergo irreversible changes during initial cycling to form stable surface layers or phases. These dopants act as short-living protective components that sacrifice themselves to prevent capacity deterioration in the main OLO structure, thereby extending the operational life of the electrode material
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 OLO material achieves high capacity and improved cycle-life characteristics at high voltages, reducing voltage drops and maintaining performance over repeated charge and discharge cycles.
Implementation Method 1
heat-treating the mixture to obtain overlithiated layered oxide (OLO)
Implementation Method 2
stabilizes the structure through oxidation reduction reactions, enhancing charge and discharge capacity
Data Source
AI summary
In an aspect, a positive active material for a rechargeable lithium battery including overlithiated layered oxide (OLO), a method of preparing the same, and a positive electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same is disclosed.