LNMO Precursor Synthesis via Segregated Reactor Design
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Solution Overview
Problem
Current methods for producing lithium nickel manganese oxide (LNMO) battery materials result in broad particle size distributions and require complex reactor designs, which negatively impact the cycling behavior and tap density of batteries, and often use ammonia as a chelating agent.
Innovation Solution
A method for upscalable precipitation synthesis involving multiple stirred tank reactors, where seed formation is separated in time and space from particle growth, allowing for tunable particle size distribution without the need for particle size separation or selection, using a specific reaction scheme and adjusting pH levels to control agglomeration and growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single stirred tank reactor is used for continuous precipitation, then the production process is simple, but the particle size distribution is broad which negatively impacts battery performance
Solution Approach 1:
The precipitation process is divided into two separate reactors: a continuous stirred tank reactor (CSTR) for seed formation and a batch stirred tank reactor (BSTR) for particle growth. This segmentation allows each reactor to be optimized for its specific function, resulting in narrow particle size distribution while maintaining process simplicity.
Solution Approach 2:
Seed particles are formed first in the CSTR before being transferred to the BSTR for growth. This preliminary action of creating uniform seeds ensures that subsequent growth occurs on consistently sized particles, leading to narrow final particle size distribution.
2Manufacturing precision
If particle size separation is used to achieve narrow particle size distribution, then battery performance is improved, but the production process becomes more complex and less scalable
Solution Approach 1:
The particle size separation step is completely eliminated from the process. Instead of producing broad distribution particles and then separating them, the process directly produces narrow distribution particles through the two-reactor precipitation method, removing the need for additional separation equipment and process steps.
Solution Approach 2:
The system self-regulates particle size distribution through controlled precipitation kinetics in the two-reactor setup, without requiring external intervention for size selection or separation. The process inherently produces the desired narrow distribution.
3Manufacturing precision
If ammonia is used as a chelating agent in precipitation, then particle formation is controlled, but the production becomes less cost-effective and environmentally friendly
Solution Approach 1:
The process replaces expensive and environmentally problematic ammonia with cheaper, environmentally benign alternatives such as sodium hydroxide or potassium hydroxide as precipitating agents, and uses carbonate/bicarbonate buffers for pH control instead of ammonia chelating agents.
Solution Approach 2:
The process changes the chemical parameters by eliminating ammonia-based chelating agents and using alternative pH control mechanisms through carbonate/bicarbonate buffering systems, achieving similar particle formation control without the drawbacks of ammonia.
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 approach produces high-quality LNMO precursor materials with a narrower particle size distribution, enhancing battery performance by reducing stress on particles during charging and discharging, and eliminating the need for ammonia, resulting in more efficient and cost-effective production.
Implementation Method 1
a method for upscalable precipitation synthesis for the production of materials with tunable particle size distribution
Implementation Method 2
seed formation is separated in time and space from particle growth, allowing for tunable particle size distribution
Data Source
AI summary
A metal carbonate material comprising nickel and manganese in an atomic ratio of 0 ≤ Ni:Mn ≤ 1/3 is produced by a method for precipitation synthesis, where seed particles are produced continuously, agglomerated and grown in a first reactor, a specific amount of the product suspension is transferred batch-wise or continuously to a stirred second reactor, and a further continuous feed of raw materials in a fixed ratio is added to this second reactor to grow the particles. This step is optionally repeated one or more times, and then the final product is collected batch-wise or continuously from the last reactor.