High-Nickel Hydroxide Precipitation for pH-Stable Cathode Precursors
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Solution Overview
Problem
Existing lithium ion batteries have limitations in energy density and cycling stability due to sensitive pH-dependent processes in precursor production, making it challenging to achieve high volumetric energy density and efficient lithiation of cathode active materials.
Innovation Solution
A process for producing particulate (oxy)hydroxides of metals with at least 60 mol-% nickel, involving the combination of aqueous solutions containing water-soluble salts and alkali metal hydroxide in a stirred tank reactor at controlled pH values, which creates stable solid particles with specific particle size and surface area characteristics, enhancing the properties of cathode active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional precipitation processes are used to produce cathode active materials, then the basic material structure is formed, but the process is very sensitive to pH value changes which significantly impact precursor properties such as particle diameter and lead to poor cycling stability
Solution Approach 1:
The patent introduces a complexing agent as an intermediary substance that binds to metal ions in the precipitation process. This complexing agent acts as a buffer that reduces the sensitivity of the precipitation reaction to pH changes, thereby stabilizing particle diameter and improving cycling stability without sacrificing manufacturing precision
Solution Approach 2:
The patent modifies the chemical environment by adding a complexing agent, which changes the effective parameters of the precipitation process. This parameter change (introduction of complexing agent) transforms the system from one that is highly sensitive to pH into one that is more robust, allowing for better control of particle properties and improved reliability
2Quantity of substance
If high nickel content (at least 60 mol-%) is used in cathode active materials to increase energy density, then volumetric energy density is improved, but the materials become more reactive and harder to lithiate efficiently
Solution Approach 1:
The patent applies preliminary action by controlling the precipitation process to create particles with specific surface area and porosity characteristics before the lithiation step. This preliminary structuring of the high-nickel material ensures that subsequent lithiation can proceed efficiently despite the high reactivity and difficulty associated with high nickel content materials
Solution Approach 2:
The patent utilizes porous material structures in the precursor particles, creating controlled porosity that facilitates lithium ion diffusion into high-nickel cathode materials. This porous structure makes the otherwise difficult-to-lithiate high-nickel materials more amenable to efficient lithiation while maintaining high volumetric energy density
3Quantity of substance
If particle size is reduced to improve volumetric energy density, then more material can be packed into the battery, but the surface area to volume ratio increases which can lead to unwanted side reactions and reduced stability
Solution Approach 1:
The patent changes the parameters of particle formation by using a complexing agent during precipitation, which allows for the creation of particles with optimized surface area to volume ratios. This parameter change enables small particle size for high volumetric energy density while controlling surface properties to maintain stability and reduce unwanted side reactions
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 precursors with improved volumetric energy density and cycling stability, enabling efficient lithiation and robustness against pH changes, leading to enhanced performance in lithium ion batteries.
Implementation Method 1
combining a solution (α) and a solution (β) and, if applicable, a solution (γ) at a pH value in the range of from 10.0 to 13.0 in a stirred tank reactor, thereby creating solid particles of a hydroxide containing nickel
Data Source
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AI summary
The present invention is directed towards a process for making a particulate (oxy)hydroxide of TM wherein TM are metals and TM comprises at least 60 mol-% nickel and wherein said pro-cess comprises the steps of:(a) Providing an aqueous solution (α) containing water-soluble salts of Ni and of at least one metal selected from Co and Mn, and, optionally, at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, and in the range of from 0.01 to 0.05 mol-%, referring to TM, of α- or β-amino acid or its alkali metal salt, and an aqueous solution (β) containing an alkali metal hydroxide and, optionally, an aqueous solution (γ) containing ammonia,(b) combining a solution (α) and a solution (β) and, if applicable, a solution (γ) at a pH value in the range of from 11.0 to 13.0 in a stirred tank reactor, thereby creating solid particles of a hydroxide containing nickel, said solid particles being slurried.