Cathode Active Material Heating via Conduction Rollers
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Solution Overview
Problem
The existing methods for manufacturing cathode active materials for lithium ion secondary batteries, such as those using rotary and roller hearth kilns, face challenges with high production costs due to the need for active air feeding and temperature irregularities, which result in variations in crystallinity and require longer heating times.
Innovation Solution
A manufacturing apparatus and method utilizing a conveying device and a heating unit with heating rollers that heat the cathode active material raw material by heat conduction, allowing for efficient and uniform heating of both surfaces of the material in an oxidizing atmosphere, reducing temperature irregularities and shortening the firing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotary kiln is used to oxidize metal hydroxides and lithium compounds, then the oxidation reaction can be promoted, but active air or oxygen feeding is required which increases production costs
Solution Approach 1:
The patent uses the material's own oxidation reaction to generate heat for subsequent firing processes. The exothermic oxidation of metal hydroxides and lithium compounds in the calcination step provides thermal energy that reduces or eliminates the need for external fuel sources in the firing step, making the system self-sufficient and reducing production costs
Solution Approach 2:
The patent changes the heating method from external combustion heating to internal heat conduction through heated rollers. The raw material is conveyed on heated rollers that transfer heat directly through conduction, eliminating the need for active air feeding and external combustion sources, thereby reducing production costs while maintaining oxidation effectiveness
2Temperature
If a roller hearth kiln is used for firing, then higher temperatures can be achieved, but temperature irregularity occurs due to hot air flow patterns which requires long heating times to suppress
Solution Approach 1:
The patent replaces the conventional roller hearth kiln's hot air convection heating system with a mechanical heat conduction system using heated rollers. The rollers are heated to high temperatures and directly contact the raw material, transferring heat through conduction rather than convection. This eliminates temperature irregularities caused by hot air flow patterns while maintaining high firing temperatures
Solution Approach 2:
The patent performs calcination before firing to convert metal hydroxides to metal oxides and lithium compounds to lithium oxide. This preliminary oxidation step creates a more thermally stable material that responds better to the subsequent heat conduction firing process, reducing temperature irregularity and allowing for shorter heating times
3Manufacturing precision
If long-term heating is used to suppress temperature irregularity in roller hearth kiln, then manufacturing precision improves, but productivity decreases and facility size increases
Solution Approach 1:
The patent replaces the slow hot air convection heating system with rapid heat conduction through heated rollers. The direct contact between the heated rollers and raw material enables fast, uniform heat transfer that achieves temperature uniformity in much shorter time, thereby improving productivity without sacrificing crystallinity uniformity
Solution Approach 2:
The patent uses a continuous conveying system where the raw material moves periodically through the heating zone on rotating heated rollers. This periodic contact with heated surfaces ensures uniform heating throughout the material while maintaining continuous production flow, improving both productivity and temperature uniformity
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 improves productivity by reducing variations in crystallinity and allowing for one-step firing, thereby decreasing production costs and facility size requirements.
Implementation Method 1
a heating unit with at least one heating member adapted to heat the cathode active material raw material by heat conduction
Implementation Method 2
the oxidation reaction between the metal hydroxide and the lithium compound, which is an endothermic reaction
Data Source
AI summary
Provided is a manufacturing apparatus of a cathode active material for lithium ion secondary batteries that enables productivity to improve. The manufacturing apparatus of a cathode active material for lithium ion secondary batteries includes: a conveying device conveying a cathode active material raw material that contains a metallic compound and a lithium compound, the metallic compound including at least one metallic element selected from the group consisting of nickel, cobalt and manganese; and a heating unit adapted to heat the cathode active material raw material, wherein the heating unit has at least one heating member adapted to heat the cathode active material raw material by heat conduction.