Transition Metal Precursor for Lithium Composite Oxide Synthesis
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Solution Overview
Problem
Current lithium transition metal oxide cathode active materials, such as LiNiO2, face challenges including high production costs, poor chemical stability, and issues like swelling and gelation due to reaction by-products, which are not adequately addressed by existing synthesis methods.
Innovation Solution
A composite transition metal compound, represented by Ni b Mn c Co 1-(b+c+d) M' d (OH 1-x) 2, is developed, allowing for a transition metal precursor with an oxidation number closer to +3, simplifying the oxidation or reduction process and reducing by-product formation during lithium transition metal oxide synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiNiO2-based cathode active materials are used to achieve high discharge capacity and improved energy density, then the capacity and energy density are improved, but production costs increase, chemical stability deteriorates, and swelling occurs due to gas evolution
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains LiNiO2 for high capacity and the outer shell contains LiMn1-x-yNixCoyO4 for stability. This allows different regions of the cathode material to have different properties - the core provides high discharge capacity while the shell provides chemical stability and prevents gas evolution, thus resolving the contradiction between capacity and reliability.
Solution Approach 2:
The patent uses composite materials by combining LiNiO2 with LiMn1-x-yNixCoyO4 to form a core-shell structured cathode active material. This composite structure allows the material to simultaneously exhibit the high capacity characteristics of LiNiO2 and the high stability characteristics of the spinel lithium manganese nickel cobalt oxide, thereby resolving the contradiction between discharge capacity and chemical stability.
2Duration of action of stationary object
If LiCoO2 is used as cathode active material to achieve excellent cycle characteristics, then cycle life is improved, but production cost increases due to finite cobalt resources and safety issues arise
Solution Approach 1:
The patent applies parameter changes by modifying the composition parameters of the cathode material. Instead of using pure LiCoO2, the patent creates a composite with adjustable ratios of LiNiO2 and LiMn1-x-yNixCoyO4, where x and y can be optimized to achieve the desired balance between cycle life and cost. This allows tuning of the material properties to maintain excellent cycle characteristics while reducing dependence on expensive cobalt.
3Ease of manufacture
If simple solid-state reaction is used to synthesize lithium transition metal active materials, then manufacturing process is simple, but synthesis of materials containing two or more transition metals is difficult
Solution Approach 1:
The patent applies preliminary action by pre-synthesizing the core LiNiO2 and shell LiMn1-x-yNixCoyO4 materials separately using simple solid-state reaction methods, then combining them in a controlled manner. This preliminary preparation of components allows the complex multi-metal material to be synthesized through a manageable multi-step process, overcoming the limitation of simple solid-state reaction while maintaining manufacturing simplicity.
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 resulting lithium transition metal composite oxide exhibits superior performance as a cathode active material with reduced reaction by-products, enhancing high-temperature stability and cycle characteristics, and improving energy density in lithium secondary batteries.
Implementation Method 1
a transition metal precursor which is used in the preparation of a lithium transition metal oxide and contains a certain composite transition metal compound
Implementation Method 2
allowing for a transition metal precursor with an oxidation number closer to +3, simplifying the oxidation or reduction process
Data Source
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AI summary
Provided is a transition metal precursor comprising a composite transition metal compound represented by Formula 1, as a transition metal precursor used in the preparation of a lithium-transition metal composite oxide: M(OH1-x)2 (1) wherein M is two or more selected from the group consisting of Ni, Co, Mn, Al, Cu, Fe, Mg, B, Cr and the transition metals of 2 period in the Periodic Table of the Elements; and 0<x<0.5. The transition metal precursor in accordance with the present invention has an oxidation number of a transition metal approximate to an oxidation number of a transition metal of the lithium-transition metal composite oxide prepared therefrom. Therefore, when the lithium-transition metal composite oxide is prepared using such a precursor, an oxidation or reduction process for varying an oxidation number can be simplified, resulting in superior process efficiency. In addition, the-thus prepared lithium-transition metal composite oxide not only exhibits excellent performance as a cathode active material, but also shows significantly less production of reaction by-products such as Li2CO3 or LiOH·H2O, which consequently can provide a solution to problems such as gelation of slurry, deterioration in high-temperature performance of the fabricated battery, swelling at high temperatures, etc., due to undesirable by-products.