Lithium Manganese Iron Phosphate Cathode Synthesis With Lower Resistivity
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Solution Overview
Problem
Existing methods for preparing positive electrode materials in secondary batteries result in significant side reaction gases and by-products, leading to decreased compacted density and increased resistivity, which adversely affect energy density and rate performance.
Innovation Solution
A method involving the reaction of a lithium source with a phosphoric acid solution followed by mixing with manganese hydrogen phosphate and an iron source, optionally with a carbon source and an M element, and subsequent drying and sintering to form lithium manganese iron phosphate positive electrode materials, which reduces side reactions and improves lithium-ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to prepare positive electrode materials, then the preparation process is simple, but side reaction gases and by-products increase, leading to decreased compacted density and increased resistivity
Solution Approach 1:
The preparation process is divided into multiple sequential steps: first reacting lithium source with phosphoric acid solution to form lithium phosphate, then mixing with other raw materials, and finally sintering. This segmentation reduces side reactions by controlling the reaction sequence and minimizing harmful by-products while improving compacted density.
Solution Approach 2:
The lithium source is preliminarily reacted with phosphoric acid solution before mixing with other raw materials. This preliminary action forms lithium phosphate in advance, which reduces side reactions during the main synthesis process and decreases harmful by-products, thereby improving the compacted density of the final product.
2Manufacturing precision
If conventional preparation methods are used, then the process is straightforward, but resistivity of the positive electrode material increases
Solution Approach 1:
The synthesis process is segmented into distinct stages: preliminary reaction of lithium source with phosphoric acid, mixing with controlled ratios of other raw materials, and sintering at specific temperatures. This segmentation enables better control over material properties, reducing resistivity through optimized reaction conditions and phase formation.
Solution Approach 2:
The invention optimizes multiple parameters including the ratio of lithium source to phosphoric acid, sintering temperature (600-800°C), and composition ratios (x+y=0.96-1.04). These parameter changes control the crystalline structure and phase purity, thereby reducing resistivity of the positive electrode material.
3Manufacturing precision
If side reactions are reduced through optimized preparation, then compacted density increases, but the preparation process becomes more complex
Solution Approach 1:
The preliminary reaction between lithium source and phosphoric acid solution is performed before mixing with other materials. This preliminary action simplifies the overall process by pre-forming lithium phosphate, which reduces side reactions during sintering and improves compacted density without requiring complex multi-step procedures.
Solution Approach 2:
The optimized preparation process uses self-service mechanisms where the controlled reaction sequence and composition ratios automatically minimize side reactions and maximize compacted density. The process parameters are designed to self-optimize the material properties without requiring complex external control systems.
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 method enhances the compacted density and lowers resistivity of the positive electrode material, thereby improving specific capacity and rate performance of the battery.
Implementation Method 1
mixing a lithium source with a phosphoric acid solution to obtain a first mixture
Implementation Method 2
drying and sintering the second mixture to obtain a lithium manganese iron phosphate positive electrode material
Data Source
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AI summary
A method for preparing a positive electrode material, a positive electrode material, a positive electrode plate, a battery, and an electric apparatus are provided. The method includes: mixing a lithium source with a phosphoric acid solution to obtain a first mixture; mixing the first mixture with manganese hydrogen phosphate, an iron source, and an optional source of an M element to obtain a second mixture; and drying and sintering the second mixture to obtain a lithium manganese iron phosphate positive electrode material; where the M element includes one or more of transition metal elements other than manganese and iron, Group IIA metal elements, Group IIIA metal elements, Group IVA metal elements, and Group VIIA elements. The method reduces side reaction gases and by-products, increases the compacted density of the positive electrode material, lowers the resistivity of the positive electrode material, and improves the specific capacity and rate performance of a battery.