Nickel Composite Hydroxide Crystallization for Low-Impurity Battery Cathodes
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Solution Overview
Problem
Lithium nickel composite oxides used in non-aqueous electrolyte secondary batteries have low crystallinity due to impurities like sulfate radicals and chlorine, leading to reduced battery capacity and safety concerns, particularly when synthesized using nickel composite hydroxides with high impurity content.
Innovation Solution
A nickel composite hydroxide with a specific composition and structure, produced through a crystallization reaction using a mixed solution of alkali metal hydroxide and carbonate, is developed to minimize impurities, resulting in a nickel composite hydroxide with reduced sulfate and chlorine content, which improves the crystallinity of the lithium nickel composite oxide when calcined with a lithium compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a lithium nickel composite oxide is synthesized using a nickel composite hydroxide with high impurity content (sulfate radicals and chlorine), then the manufacturing cost is reduced and the synthesis process is simplified, but the crystallinity of the lithium nickel composite oxide is reduced, leading to lower battery capacity and safety issues
Solution Approach 1:
The patent applies preliminary action by performing a washing treatment on the nickel composite hydroxide precursor before synthesizing the lithium nickel composite oxide. This preliminary cleaning step removes sulfate radicals and chlorine impurities from the surface of the nickel composite hydroxide particles, ensuring that the subsequent solid-phase reaction produces a lithium nickel composite oxide with high crystallinity and excellent battery performance, while still maintaining a simple overall manufacturing process.
2Quantity of substance
If a lithium nickel composite oxide is synthesized using a nickel composite hydroxide with high impurity content, then the manufacturing cost is reduced, but the battery capacity and safety are compromised
Solution Approach 1:
The washing treatment is performed as a preliminary step to remove impurities from the nickel composite hydroxide precursor. This preliminary action ensures that the lithium nickel composite oxide synthesized from this precursor achieves high crystallinity and excellent battery performance, effectively resolving the contradiction between maintaining low manufacturing costs and ensuring high reliability.
3Ease of manufacture
If impurities like sulfate radicals and chlorine are present in the nickel composite hydroxide, then the synthesis process remains simple and cost-effective, but the crystallinity of the resulting lithium nickel composite oxide is reduced
Solution Approach 1:
The patent applies the extraction principle by selectively removing impurities (sulfate radicals and chlorine) from the nickel composite hydroxide precursor through a washing treatment using deionized water. This extraction step separates the harmful impurities from the useful nickel composite hydroxide particles, allowing the subsequent synthesis to produce a lithium nickel composite oxide with high crystallinity while keeping the overall process simple and cost-effective.
4Manufacturing precision
If a washing treatment is performed to remove impurities from nickel composite hydroxide, then the crystallinity and battery performance are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies partial action by performing a washing treatment that targets only the surface impurities (sulfate radicals and chlorine) of the nickel composite hydroxide particles, rather than attempting to purify the entire material structure. This partial purification approach is sufficient to achieve high crystallinity in the final lithium nickel composite oxide without requiring multiple complex processing steps, thus balancing manufacturing precision with process simplicity.
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 yields a nickel composite hydroxide with low impurity content, enhancing the battery's capacity and safety by ensuring high crystallinity of the lithium nickel composite oxide, thus achieving a higher capacity and improved cycle characteristics for non-aqueous electrolyte secondary batteries.
Implementation Method 1
a process for producing a nickel composite hydroxide by a crystallization reaction
Implementation Method 2
EP 2763 220 A2 discloses a process for the preparation of a nickel complex hydroxide by crystallisation reaction starting from an aqueous solution of metal sources
Implementation Method 3
which is adjusted to have a composition represented by a general formula: Li t Ni 1‑x‑y Co x Al y O 2
Data Source
AI summary
Disclosed herein is a nickel composite hydroxide containing reduced amounts of sulfate radicals and chlorine as impurities. The nickel composite hydroxide is represented by Ni1-x-yCoxAly(OH)2+α (0.05 ≤ x ≤ 0.35, 0.01 ≤ y ≤ 0.2, x + y < 0.4, and 0 ≤ α ≤ 0.5), and includes spherical secondary particles formed by aggregation of a plurality of plate-shaped primary particles, wherein the secondary particles have an average particle diameter of 3 to 20 µm, a sulfate radical content of 1.0 mass% or less, a chlorine content of 0.5 mass% or less, and a carbonate radical content of 1.0 mass% to 2.5 mass%. The nickel composite hydroxide is obtained by a process including a crystallization step in which crystallization is performed in a reaction solution obtained by adding an alkali solution to an aqueous solution containing a mixed aqueous solution containing nickel and cobalt, an ammonium ion supplier, and an aluminum source, wherein the alkali solution is a mixed aqueous solution of an alkali metal hydroxide and a carbonate, and a ratio of the carbonate to the alkali metal hydroxide in the mixed aqueous solution represented by [CO32-]/[OH-] is 0.002 or more but 0.050 or less.