Oxyhydroxide Precursor for Nickel-Rich Cathode Materials
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Solution Overview
Problem
Nickel-rich cathode active materials for lithium metal oxides suffer from cation mixing due to the similarity in radii of Ni2+ and Li+ ions, leading to blocked lithium diffusion pathways and reduced performance, and additional processing steps to incorporate nickel in the +3 oxidation state are costly and inefficient.
Innovation Solution
A cathode active material precursor comprising a metal-containing oxyhydroxide with at least 50 mol% nickel in the +3 oxidation state, formed by combining nickel and additional metal compounds with an oxidizing agent and solvent, then heat-treated to minimize cation mixing and enhance lithium diffusion pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional hydroxide precursors (Ni yM1-y(OH)2) are used, then the material can be easily manufactured, but cation mixing occurs between Ni2+ and Li+ ions leading to blocked lithium diffusion pathways
Solution Approach 1:
The patent changes the oxidation state parameter of nickel from +2 in conventional hydroxide precursors to +3 in the oxyhydroxide precursor (NiyM1-y(OOH)2). This parameter change creates electrostatic repulsion between Ni3+ and Li+ ions, preventing cation mixing and blocking of lithium diffusion pathways while maintaining ease of manufacture through a modified precipitation process.
Solution Approach 2:
The patent introduces an oxidizing agent as an intermediary substance during the precursor formation process. This oxidizing agent converts Ni2+ to Ni3+ in situ, creating the beneficial electrostatic repulsion effect without requiring separate calcination steps. The oxidizing agent acts as a mediator that transforms the precursor chemistry to achieve both ease of manufacture and improved lithium diffusion.
2Reliability
If additional calcination in oxygen-rich environment is performed to incorporate Ni3+, then nickel oxidation state improves, but operating cost increases and capital investment is required
Solution Approach 1:
The patent performs the oxidation of nickel to the +3 state during the initial precursor formation process rather than requiring a separate subsequent calcination step. By incorporating the oxidizing agent in the precipitation step, the nickel is pre-oxidized before lithiation, eliminating the need for additional capital-intensive calcination facilities and reducing operating costs while achieving the desired Ni3+ oxidation state.
Solution Approach 2:
The patent merges the precursor formation process with the nickel oxidation process by adding the oxidizing agent to the precipitation reaction. This combines two separate operations (precursor synthesis and nickel oxidation) into a single step, eliminating the need for separate calcination equipment and reducing both capital investment and operating costs while achieving Ni3+ incorporation.
3Device complexity
If conventional hydroxide precursors are used, then the process is simple, but considerable Ni2+ ions remain blocking lithium diffusion pathways
Solution Approach 1:
The patent changes the chemical composition parameter of the precursor from hydroxide (—OH) to oxyhydroxide (—OOH) form with Ni3+. This parameter change fundamentally alters the interaction between nickel and lithium ions, creating electrostatic repulsion that prevents Ni2+ from blocking lithium diffusion pathways. The process complexity increases only minimally by adding an oxidizing agent to the existing precipitation process.
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 oxyhydroxide form of the precursor reduces cation mixing, maintaining nickel ions in the +3 state during calcination, thereby improving the performance of the resulting lithium metal oxide by maintaining open lithium diffusion pathways and enhancing capacity utilization.
Implementation Method 1
At least 50 mol. % of the nickel of the metal-containing oxyhydroxide has an oxidation state of +3
Implementation Method 2
further calcination of the nickel-containing hydroxide precursors in an oxygen rich environment
Implementation Method 3
the oxyhydroxide form (—OOH) of the cathode active material precursor incorporates nickel ions in a +3 oxidation state thereby minimizing cation mixing with lithium
Data Source
AI summary
A cathode active material precursor for a lithium metal oxide is provided. The cathode active material precursor comprises a metal-containing oxyhydroxide. The metal-containing oxyhydroxide comprises nickel and an additional metal. At least 50 mol. % of the nickel of the metal-containing oxyhydroxide has an oxidation state of +3. A method of forming a cathode active material precursor is also provided. The method comprises combining a nickel-containing compound, an additional metal-containing compound, an oxidizing agent, and a solvent to form a solution. The method further comprises exposing the solution to heat at a temperature of from about 30° C. to about 90° C. to form a precipitate comprising the metal-containing oxyhydroxide.