Cathode Intermediate Calcination for Rotary Kiln Processing

Solution Overview

Problem

The existing processes for forming cathode active materials in lithium-ion batteries rely heavily on high-temperature kilns and ceramic kiln furniture, which are costly and inefficient, and struggle with controlling oxygen partial pressure due to CO2 and water evolution during calcination, limiting the use of rotary kilns and resulting in low-volume, stagnant heating processes.

Innovation Solution

A method is developed to form an intermediate material from a precursor comprising lithium salts and multi-carboxylic acid salts of nickel, manganese, or cobalt, which can be heated in a metal-lined rotary kiln at lower temperatures (up to 600°C) to produce a free-flowing powder, reducing the need for ceramic kiln furniture and allowing for direct calcination in a controlled atmosphere at higher temperatures, thereby reducing production time and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-temperature kilns and ceramic kiln furniture are used for calcining precursors, then the cathode active material can be formed, but the production cost increases and the process efficiency decreases

Engineering Contradiction:

Improvecathode material formationVSAvoidproduction efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The calcination process is divided into two distinct stages: (1) a first calcination stage at lower temperature (400-600°C) in a metal-lined kiln to form an intermediate material, and (2) a second calcination stage at higher temperature (700-900°C) in a ceramic kiln to form the final cathode active material. This segmentation allows each stage to be optimized independently, reducing overall process time and cost while maintaining product quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first calcination stage performs preliminary processing of the precursor to form an intermediate material with favorable properties for the second stage. This preliminary action removes volatile components, forms a stable intermediate structure, and prepares the material for efficient final calcination, thereby reducing the time and energy required in the second stage.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If ceramic kiln furniture is used for high-temperature calcination, then the process can handle molten lithium hydroxide, but the equipment cost and complexity increase

Engineering Contradiction:

Improvecorrosion resistance to molten lithium hydroxideVSAvoidkiln furniture requirements

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The calcination process is divided into two distinct stages: (1) a first calcination stage at lower temperature (400-600°C) in a metal-lined kiln to form an intermediate material, and (2) a second calcination stage at higher temperature (700-900°C) in a ceramic kiln to form the final cathode active material. This segmentation allows each stage to be optimized independently, reducing overall process time and cost while maintaining product quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The intermediate material serves as a mediator between the precursor and the final cathode active material. By forming this intermediate stage at lower temperature in a metal-lined kiln, the process avoids direct exposure of metal equipment to molten lithium hydroxide during the high-temperature stage, thus reducing equipment complexity and cost.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If precursors are calcined directly to form cathode active material, then the process is simple, but control of oxygen partial pressure is difficult due to CO2 and water evolution

Engineering Contradiction:

Improveprocess simplicityVSAvoidoxygen partial pressure control

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The calcination process is divided into two distinct stages: (1) a first calcination stage at lower temperature (400-600°C) in a metal-lined kiln to form an intermediate material, and (2) a second calcination stage at higher temperature (700-900°C) in a ceramic kiln to form the final cathode active material. This segmentation allows each stage to be optimized independently, reducing overall process time and cost while maintaining product quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first calcination stage performs preliminary processing of the precursor to form an intermediate material with favorable properties for the second stage. This preliminary action removes volatile components, forms a stable intermediate structure, and prepares the material for efficient final calcination, thereby reducing the time and energy required in the second stage.

Inventive Principle:

Principle #10Preliminary action

4Productivity

If rotary kilns are used for high-volume production, then productivity increases, but the molten lithium hydroxide degrades the kiln surface

Engineering Contradiction:

Improveproduction volumeVSAvoidkiln surface degradation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The calcination process is divided into two distinct stages: (1) a first calcination stage at lower temperature (400-600°C) in a metal-lined rotary kiln to form an intermediate material, and (2) a second calcination stage at higher temperature (700-900°C) in a ceramic kiln to form the final cathode active material. This segmentation allows the use of rotary kilns for high-volume production in the first stage without surface degradation, while the second stage handles the high-temperature requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The process changes the temperature parameter from high (700-900°C) in the second stage to lower (400-600°C) in the first stage. This parameter change allows the use of metal-lined rotary kilns in the first stage, which can handle high-volume production without surface degradation from molten lithium hydroxide, while still achieving the desired product quality through the two-stage process.

Inventive Principle:

Principle #35Parameter changes

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 enables the efficient formation of a lithiated cathode material with a high surface area and desired crystalline structure, optimizing kiln utilization and reducing the reliance on ceramic kiln furniture, while allowing for larger volume production and improved control of the calcination process.

Implementation Method 1

heating the precursor in a metal lined vessel to a temperature of no more than 600° C. to form an intermediate material

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

heating the intermediate material to a temperature of over 600° C. to form the active cathode material

Methodology Applied

Scientific EffectCalcination: Heating

Data Source

PatentUS12077452B2Intermediate material between precursor and cathode active material

Publication Date: 2024.09.03 NANO ONE MATERIALS

AI summary

A process for forming an active cathode material. The process comprises forming a precursor comprising a lithium salt and a multi-carboxylic acid salt of at least one of nickel, manganese or cobalt; heating the precursor in a metal lined vessel to a temperature of no more than 600° C. to form an intermediate material; and heating the intermediate material to a temperature of over 600° C. to form said active cathode material.