High-Nickel Cathode Sintering With Non-Corrosive Lithium Salts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lithium ion battery production processes using high nickel cathode materials face challenges due to the corrosiveness of lithium hydroxide (LiOH) at high temperatures, leading to increased production costs and poor thermal stability of high nickel lithiated metal oxides, which decompose at high temperatures and release oxygen, necessitating a non-corrosive alternative.
Innovation Solution
A two-step sintering process is employed using non-corrosive lithium salts like lithium carbonate (Li2CO3) in an air environment followed by an oxygen environment to form high nickel lithiated metal oxides, reducing corrosion and improving thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithium hydroxide (LiOH) is used as lithium source at high temperature, then lithiation reaction is facilitated, but corrosion to metal components increases
Solution Approach 1:
The harmful corrosive property of LiOH is extracted and removed from the system by replacing it with non-corrosive lithium salts such as lithium carbonate (Li2CO3) or lithium acetate (LiCH3COO), while retaining the essential lithiation function through alternative chemical mechanisms
Solution Approach 2:
The patent uses consumable lithium salt additives that decompose during sintering to provide lithium ions for lithiation, replacing the need for expensive corrosion-resistant furnace components. The lithium salts serve their purpose and are consumed, eliminating ongoing corrosion maintenance costs
2Manufacturing precision
If high sintering temperature is used to form lithiated metal oxide, then reaction completeness is improved, but thermal decomposition of high nickel material occurs
Solution Approach 1:
The patent changes the chemical parameters of the lithium source from LiOH to lithium salts with higher decomposition temperatures (Li2CO3 decomposes at 723°C, LiCH3COO at 420°C but forms protective layers), enabling the system to withstand higher sintering temperatures without material decomposition
Solution Approach 2:
The lithium salts are pre-mixed with the metal oxide precursors before sintering, creating a homogeneous blend that ensures complete lithiation reaction. The salts decompose in situ during sintering to release lithium ions that immediately react with the metal oxide, ensuring complete lithiation before the material reaches its decomposition temperature
3Object-affected harmful factors
If lithium carbonate (Li2CO3) is used as lithium source, then corrosion is reduced, but CO2 release lowers O2 partial pressure and increases ion mixing
Solution Approach 1:
The patent optimizes the sintering atmosphere parameters by controlling oxygen flow rate and pressure to compensate for CO2 release from Li2CO3 decomposition. By maintaining elevated oxygen partial pressure through controlled atmosphere, the oxidation of Ni2+ to Ni3+ is promoted, reducing Li+/Ni2+ ion mixing even in the presence of CO2
Solution Approach 2:
The patent uses composite lithium salt systems combining lithium carbonate with other lithium salts such as lithium acetate or lithium nitrate. This composite approach balances the advantages and disadvantages of different lithium salts, providing sufficient lithium ions for complete lithiation while controlling CO2 release and maintaining appropriate oxygen partial pressure
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 effectively reduces production costs by minimizing corrosion and enhances the electrochemical performance of high nickel lithiated metal oxides by lowering Li+/Ni2+ mixing content.
Implementation Method 1
If Li2CO3 were used, it would release CO2 during sintering
Implementation Method 2
the nickel in the lithiated metal oxide needs to be at a high oxidation state (e.g., Ni3+), while the starting Ni (II) sulfate precursor includes nickel with an oxidation state of Ni2+. It is very difficult to oxidize Ni2+ to Ni3+ at high temperature
Implementation Method 3
LiOH is also typically used because of its low melting point (i.e., about 462° C.). A process using LiOH is able to form a fully lithiated metal oxide at a relatively low temperature (700-800° C.) because the melted LiOH helps facilitate the lithiation reaction
Data Source
AI summary
A method for preparing high nickel lithiated metal oxides that includes selecting one or more nickel precursors; at least one non-corrosive lithium salt; and a plurality of metal oxide or hydroxide precursors. The metal precursors and lithium salts are mixed together to form a mixture comprising:LixNiyMzN(1−y−z)O(2−a)Fa (F-1)wherein x=1.0-1.1, 0.80≤y≤0.90, 0.03<z≤0.15, and 0≤a≤0.05; M is Co or Fe; and N is Al, Mn, Fe, Ca, Mg, Ti, Cr, Nb, Mo, W, B, or a mixture thereof provided N may be Fe when M is Co. The mixture is subjected to sintering (1st step) in air at ≥750° C. to form a powder. The powder is subjected to a 2nd sintering step in O2 at ≤750° C. to form the high nickel lithiated metal oxides.