Li-NMC Cathode Oxide Production with Two-Stage Calcination
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Solution Overview
Problem
Current methods for producing superstoichiometric lithium-nickel-manganese-cobalt (Li-NMC) oxides require long process times and high temperatures, which can compromise safety and specific capacity as cathode materials in lithium-ion batteries.
Innovation Solution
A two-stage production process involving the thermal treatment of a mixture containing lithium, manganese, and cobalt in specific ratios, with continuous mixing and controlled oxidation levels, allowing for the production of superstoichiometric Li-NMC oxides at lower temperatures and shorter times, ensuring high safety and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high-temperature long-duration calcination is used to produce superstoichiometric Li-NMC oxides, then complete reaction and phase formation are achieved, but processing time increases and temperature requirements compromise safety and specific capacity
Solution Approach 1:
The thermal treatment process is divided into two distinct stages: first stage with continuous mixing at lower temperature to form intermediate products, and second stage without mixing at higher temperature to complete the reaction. This segmentation allows each stage to be optimized independently, achieving complete reaction without requiring prolonged high-temperature treatment, thus reducing overall processing time while maintaining safety and specific capacity.
Solution Approach 2:
The first thermal treatment stage performs preliminary formation of intermediate products (lithium-containing mixed metal hydroxides and oxide hydroxides) with controlled oxidation numbers. This preliminary action prepares the material structure for the second stage, enabling the final superstoichiometric Li-NMC oxide to form more quickly and at lower overall temperature exposure, thereby reducing processing time while preserving safety and electrochemical performance.
2Reliability
If high temperatures are applied during thermal treatment to ensure complete reaction, then phase formation is achieved, but furnace corrosion increases
Solution Approach 1:
The thermal treatment is segmented into two stages with different temperature profiles and mixing conditions. The first stage operates at lower temperature with continuous mixing to form intermediates, minimizing corrosion during this phase. The second stage uses higher temperature only for the final transformation without mixing, reducing total time at corrosive temperatures. This segmentation achieves complete phase formation while limiting cumulative furnace corrosion.
Solution Approach 2:
Lithium-containing mixed metal oxide hydroxides serve as intermediate products between the starting materials and the final superstoichiometric Li-NMC oxide. These intermediates form at lower temperatures in the first stage, acting as a mediator that enables the final high-temperature phase formation to occur more quickly and with reduced corrosion impact on the furnace.
3Device complexity
If thermal treatment is performed without continuous mixing to reduce processing complexity, then equipment requirements are simplified, but homogeneity of the final product decreases
Solution Approach 1:
The thermal treatment is segmented into two stages with different mixing requirements. The first stage uses continuous mixing to ensure homogeneous distribution of reactants and form uniform intermediate products. The second stage eliminates mixing equipment requirements, using only thermal treatment to complete the reaction. This segmentation achieves both reduced device complexity (no mixer needed in stage 2) and maintained product homogeneity (ensured in stage 1).
Solution Approach 2:
Continuous mixing is used in the first thermal treatment stage to preliminarily establish homogeneous distribution of lithium, manganese, cobalt, and nickel compounds. This preliminary homogenization ensures that when the second stage proceeds without mixing, the final product maintains high uniformity. The preliminary mixing action compensates for the absence of mixing in the second stage.
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 results in Li-NMC oxides with enhanced safety and specific capacity, achieved through controlled thermal treatment without significant furnace corrosion and improved homogeneity, enabling efficient use as cathode materials in lithium-ion batteries.
Implementation Method 1
thermal treatment, with continuous mixing and in the presence of oxygen, of a mixture (A) containing at least one transition metal compound and at least one lithium salt
Implementation Method 2
the production of a mixture referred to as intermediate product (B), which essentially contains lithium-containing mixed metal hydroxides and lithium-containing mixed metal oxide hydroxides
Implementation Method 3
In the first step, a mixture of Ni(1-x)CoyMz hydroxide and lithium hydroxide is subjected to dehydration
Implementation Method 4
thermal treatment of the intermediate product (B) without mixing and in the presence of oxygen
Data Source
AI summary
The invention relates to a method for producing lithium-mixed metal oxides which essentially contain lithium, manganese, cobalt and nickel as the metal atoms and have a stoichiometric ratio of lithium to the collectivity of the transition metals of greater than 1, comprising a) the production of a mixture referred to as the intermediate product (B), which essentially comprises lithium-containing mixed metal hydroxides and lithium-containing mixed metal oxide hydroxides, in which manganese, cobalt and nickel are contained at the ratio (1-a-b):a:b and in which the oxidation number, averaged over all ions of manganese, cobalt and nickel, is at least 4-1.75a-1.75b, where 0 < a < 0.5 and 0.1 < b < 0.8 applies, by a thermal treatment, which takes place with continuous mixing and in the presence of oxygen, of a mixture (A) containing at least one transition metal compound and at least one lithium salt (L), during which treatment L does not melt, and b) the thermal treatment of the intermediate product (B) which is carried out without mixing and in the presence of oxygen.