Mixed Hydroxide Precipitation with Coaxial Ammonia Feed Control
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Solution Overview
Problem
Existing lithium ion batteries have limitations in energy density and cycling stability due to the properties of their cathode materials, particularly the stoichiometry, morphology, and surface characteristics of the electrode materials, which affect the lithiation process and calcination temperature sensitivity.
Innovation Solution
A process for precipitating a mixed hydroxide of Ni, Co, and Mn, optionally with Al, Mg, Zr, or Ti, using a stirred vessel with coaxial inlets for introducing ammonia and transition metal salts, allowing for controlled pH and ammonia-to-metal ratios, resulting in precursors with specific particle sizes and structures that enhance volumetric energy density and cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional precipitation methods are used to prepare cathode materials, then the basic material properties are achieved, but the volumetric energy density and cycling stability are insufficient
Solution Approach 1:
The precipitation process is segmented into multiple stages with different pH values and ammonia-to-metal ratios. The patent applies multi-stage precipitation where each stage targets specific particle formation requirements, enabling precise control over particle size distribution and morphology while improving cycling stability and volumetric energy density
Solution Approach 2:
The patent systematically changes multiple parameters including pH value, ammonia-to-metal ratio, temperature, and addition rate during precipitation. By optimizing these parameters across different stages, the process achieves superior particle properties that enhance both cycling stability and volumetric energy density
2Volume of stationary object
If high calcination temperature is used to improve material density, then volumetric energy density increases, but electrochemical properties become more sensitive to temperature variations
Solution Approach 1:
The patent performs preliminary optimization of particle size, morphology, and surface properties during the precipitation stage before calcination. By pre-forming particles with optimal characteristics, the subsequent calcination process requires lower temperatures and shorter times, reducing thermal sensitivity while achieving high volumetric energy density
Solution Approach 2:
The patent changes the particle properties parameters (size distribution, surface area, porosity) during precipitation to compensate for reduced calcination severity. This allows achieving high density with milder thermal treatment, thereby maintaining electrochemical property stability
3Area of moving object
If particle size is reduced to increase surface area for better lithiation, then electrochemical performance improves, but particle aggregation and handling difficulties increase
Solution Approach 1:
The patent creates particles with specific local characteristics including controlled porosity, surface morphology, and internal structure. These localized quality features enable high surface area particles to maintain good flowability and handling properties by preventing aggregation while preserving electrochemical performance
Solution Approach 2:
The patent produces composite particle structures with controlled internal porosity and surface characteristics. The composite nature of these particles combines high surface area benefits with improved mechanical properties that facilitate handling and prevent aggregation
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 produces precursors that enable lithium ion batteries with improved volumetric energy density and cycling stability by optimizing particle diameter, porosity, and surface area, reducing the impact of calcination temperature on electrochemical properties.
Implementation Method 1
a process for precipitating a mixed hydroxide of TM wherein TM comprises Ni and at least one of Co and Mn and, optionally, Al, Mg, Zr or Ti from an aqueous solution of salts of such transition metals
Implementation Method 2
introducing a 1 to 40% by weight aqueous solution of ammonia and an aqueous solution of transition metal salts through at least two inlets into said stirred vessel
Data Source
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AI summary
Process for precipitating a mixed hydroxide of TM wherein TM comprises Ni and at least one of Co and Mn and, optionally, Al, Mg, Zr or Ti from an aqueous solution of salts of such transition metals or of Al or of Mg, wherein such process is carried out in a stirred vessel and comprises the step of introducing a 10 to 40% by weight aqueous solution of ammonia and an aqueous solution of transition metal salts through at least two inlets into said stirred vessel wherein the distance of the locations of introduction of TM and of ammonia is equal or less than 12 times the hydraulic diameter of the tip of the inlet of the ammonia, and wherein an aqueous solution ofalkali metal hydroxide is added separately from the at least two inlets.