Cathode Precursor Formation With Two-Step Oxidation and Precipitation
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Solution Overview
Problem
Existing processes for manufacturing lithium-containing mixed transition metal oxides for lithium ion batteries result in the formation of stoichiometric alkali metal sulfates and unreacted metal residues that are difficult to remove, particularly when manganese is present, leading to inefficiencies and unwanted by-products.
Innovation Solution
A process involving the combination of an aqueous slurry of metallic nickel and other metals with an oxidant in a two-step reaction, followed by solid-liquid separation and drying, to produce particulate (oxy)hydroxides with controlled pH and temperature conditions, reducing the formation of unwanted by-products and allowing for better incorporation of manganese.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional precipitation methods using metal sulfates are used to manufacture lithium-containing mixed transition metal oxides, then the cathode material can be produced, but stoichiometric amounts of alkali metal sulfates are formed as unwanted by-products that need to be disposed of
Solution Approach 1:
The invention changes the chemical parameters of the precipitation process by using metal nitrates instead of metal sulfates as starting materials, and using ammonia as the precipitating agent instead of alkali hydroxides. This parameter change transforms the reaction pathway to produce metal hydroxide precipitates without forming stoichiometric amounts of alkali metal sulfate by-products, thereby resolving the contradiction between ease of manufacture and harmful by-product generation
Solution Approach 2:
The invention converts the previously harmful ammonia by-products (NH4+ ions) into a beneficial component by incorporating them into the cathode material structure during subsequent calcination, where they facilitate lithium ion diffusion and improve battery performance. This transforms the harmful factor into a beneficial feature, resolving the contradiction between manufacturing ease and harmful by-products
2Ease of manufacture
If oxidation of metals and simultaneous precipitation is performed under alkaline conditions to manufacture precursors, then the precursor can be formed, but manganese may be precipitated as MnO2 that is not incorporated well into the precursor
Solution Approach 1:
The invention performs preliminary oxidation of manganese to Mn3+ state using nitrate oxidant before the precipitation step, and maintains controlled pH conditions during precipitation to prevent Mn4+ formation. This preliminary action ensures manganese remains in a soluble and incorporable oxidation state throughout the precursor formation process, resolving the contradiction between ease of manufacture and manufacturing precision regarding manganese incorporation
Solution Approach 2:
The invention changes the oxidation state parameters of manganese from the conventional Mn2+ to Mn3+ during the precipitation process, and controls the pH parameter to remain below 10.5 during precipitation. These parameter changes prevent the formation of MnO2 (Mn4+) and ensure manganese is properly incorporated into the precursor structure, resolving the contradiction between ease of manufacture and manganese incorporation quality
3Ease of operation
If magnetic separation is used to remove unreacted metals in the precursor manufacturing process, then metal removal can be achieved, but it does not work for many materials such as aluminum and manganese
Solution Approach 1:
The invention extracts and removes unreacted metals through filtration of the precipitated hydroxide, separating the solid precursor from the liquid phase containing dissolved metal ions. This extraction method is universally applicable to all metal types including aluminum and manganese, resolving the contradiction between ease of operation and adaptability to different metals by replacing magnetic separation with a universally effective filtration approach
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 process effectively minimizes the generation of stoichiometric alkali metal sulfates and unreacted metal residues, enabling the production of high-quality cathode active materials with improved morphology and reduced by-products, suitable for lithium ion batteries.
Implementation Method 1
combining an aqueous slurry of metallic nickel and at least one metal selected from aluminum and transition metals other than nickel with an oxidant selected from oxygen, peroxide and nitrate
Implementation Method 2
transferring aqueous reaction medium from step (a) to a second reaction vessel, wherein said second reaction vessel contains a slurry of a hydroxide of TM, wherein the pH value in step (b) is higher than in step (a) and the temperature is in the range of from 45° to 80° C., thereby forming and growing particles of hydroxide of TM
Data Source
AI summary
Disclosed herein is a process for making a particulate (oxy)hydroxide of TM, where TM represents a combination of metals and includes nickel and at least one metal selected from cobalt and aluminum and manganese. The process includes:(a) combining an aqueous slurry of metallic nickel and at least one metal selected from aluminum and transition metals other than nickel with an oxidant selected from oxygen and nitrate in a first reaction vessel or in a first group of reaction vessels at a temperature of from 5° to 40° C.,(b) transferring aqueous reaction medium from the first reaction vessel to a second reaction vessel, where the second reaction vessel contains a slurry of a hydroxide of TM,(c) removing the particles from step (b) from the liquid by a solid-liquid separation method, and drying the particles, and(d) returning liquid phase obtained in step (c) to the first reaction vessel.