Method for preparing cathode active material precursor for secondary battery, and preparation apparatus using same

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Solution Overview

Problem

The existing methods for preparing cathode active material precursors for secondary batteries generate significant wastewater and fail to effectively recycle metal ions from the co-precipitation filtrate, leading to increased raw material costs and environmental impact.

Innovation Solution

A method involving the recycling of co-precipitation filtrate through filtration, acid treatment to produce ammonium sulfate or nitrate, cooling and crystallization to precipitate sodium sulfate, and subsequent recycling of the filtrate to form a metal solution, utilizing a dedicated apparatus with tanks and membrane contactors for ammonia removal and pH adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If co-precipitation method is used to prepare cathode active material precursor, then precursor quality and constant particle diameter are achieved, but significant wastewater is generated containing ammonia, eluted metal ions, and sodium sulfate

Engineering Contradiction:

Improveprecursor qualityVSAvoidwastewater generation

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent recovers valuable components from the co-precipitation filtrate by filtering metal hydroxides, reacting with sulfuric acid to produce ammonium sulfate, cooling to precipitate sodium sulfate, and recycling the remaining filtrate back to the reactor. This transforms waste streams into recoverable resources while maintaining precursor quality.

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The patent converts harmful eluted metal ions and ammonia in the filtrate into beneficial products: metal hydroxides are filtered for recovery, ammonia reacts with sulfuric acid to form ammonium sulfate fertilizer, and sodium sulfate is precipitated through cooling. This transforms environmental hazards into valuable by-products.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Manufacturing precision

If ammonia is added as chelating agent to overcome difference in co-precipitation rate, then uniform precursor formation is achieved, but metal ions are eluted by coordinate bonding with ammonia and remain in solution

Engineering Contradiction:

Improveprecursor uniformityVSAvoidmetal ion loss

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent recovers eluted metal ions by filtering the co-precipitation filtrate to collect metal hydroxides, which are then processed through acid treatment and crystallization. This prevents metal ion loss and converts them into recoverable materials.

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The patent implements a feedback loop by recycling the co-precipitation filtrate (after removing metal hydroxides, ammonia, and sodium sulfate) back to the reactor. This returns unreacted metal ions to the process, improving overall metal ion utilization and reducing loss.

Inventive Principle:

Principle #23Feedback

3Ease of manufacture

If filter press is used to filter co-precipitation filtrate, then solid-liquid separation is achieved, but ammonia and metal ions remain dissolved in the remaining filtrate requiring separate wastewater treatment

Engineering Contradiction:

Improvefiltration efficiencyVSAvoidwastewater treatment facility

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges multiple treatment functions into a single integrated system: filtration to remove metal hydroxides, acid reaction to remove ammonia and produce ammonium sulfate, cooling crystallization to remove sodium sulfate, and filtration to separate the precipitated salts. The remaining filtrate is then recycled back to the reactor, eliminating the need for separate wastewater treatment facilities.

Inventive Principle:

Principle #5Merging (Combining)

4Manufacturing precision

If washing liquid is used to wash precursor after filtration, then precursor purity is improved, but waste water is generated at about 50 tons per 1 ton of precursor

Engineering Contradiction:

Improveprecursor purityVSAvoidwastewater volume

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent recovers valuable components from the washing liquid and co-precipitation filtrate by filtering metal hydroxides, reacting with sulfuric acid to produce ammonium sulfate, cooling to precipitate sodium sulfate, and recycling the remaining filtrate. This dramatically reduces wastewater volume while maintaining precursor purity through the filtration and crystallization processes.

Inventive Principle:

Principle #34Discarding and recovering

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 significantly reduces wastewater generation, recycles valuable metal ions, and maximizes yield by converting by-products into usable materials like ammonium sulfate and sodium sulfate, thereby enhancing the efficiency and sustainability of the cathode active material precursor production process.

Implementation Method 1

reacting the co-precipitation filtrate from which the metal hydroxide is removed with sulfuric acid or nitric acid to produce an ammonium sulfate or an ammonium nitrate while removing ammonia from the co-precipitation filtrate

Methodology Applied

Scientific EffectAcid-base reaction: Chemical Bonding

Implementation Method 2

cooling and crystallizing the co-precipitation filtrate from which the metal hydroxide and ammonia are removed to precipitate a sodium sulfate

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 3

passing the co-precipitation filtrate through a membrane contactor to remove ammonia from the co-precipitation filtrate

Methodology Applied

Scientific EffectGas absorption: Absorption (physical)

Implementation Method 4

passing the co-precipitation filtrate through a filter press to remove a metal hydroxide from the co-precipitation filtrate

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Data Source

PatentUS11827524B2Method for preparing cathode active material precursor for secondary battery, and preparation apparatus using same

Publication Date: 2023.11.28 POSCO HLDG INC

AI summary

A method for preparing a cathode active material precursor for a secondary battery, including: moving a co-precipitation filtrate generated after a co-precipitation reaction to a co-precipitation filtrate storage tank; removing a metal hydroxide by passing the co-precipitation filtrate through a filter; reacting the co-precipitation filtrate from which the metal hydroxide is removed with sulfuric acid or nitric acid to produce an ammonium sulfate or an ammonium nitrate while removing ammonia from the co-precipitation filtrate from which the metal hydroxide is removed; cooling and crystallizing the co-precipitation filtrate from which the metal hydroxide and ammonia are removed to precipitate a sodium sulfate; filtering the precipitated sodium sulfate to separate the precipitated sodium sulfate from the co-precipitation filtrate from which the metal hydroxide and ammonia are removed; drying the sodium sulfate separated from the co-precipitation filtrate and moving the co-precipitation filtrate separated from the sodium sulfate to a circulation concentration tank; and heating the co-precipitation filtrate stored in the circulation concentration tank to a predetermined temperature for recycling and performing N2 purging or bubbling, is provided.