Lithium Manganese Iron Phosphate Cathode with High Tap Density
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Solution Overview
Problem
Current lithium manganese iron phosphate positive electrode materials struggle to achieve both good electrochemical performance and high energy density due to uncontrollable morphology and size, leading to low tap density and volumetric energy density in secondary batteries.
Innovation Solution
A method involving a low temperature solid phase reaction to prepare nanoscale iron-containing oxide, followed by granulation via spray drying and sintering, to produce a lithium manganese iron phosphate positive electrode active material with controlled morphology and high tap density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional preparation methods are used for lithium manganese iron phosphate positive electrode material, then the material can be produced, but the morphology and size are uncontrollable, resulting in low tap density and poor electrochemical performance
Solution Approach 1:
The preparation process is divided into multiple stages: first preparing nanoscale iron-containing oxide particles through low-temperature solid phase reaction, then using these as precursors in a second sintering step to form the final lithium manganese iron phosphate material. This segmentation allows morphology control at the nanoscale level while maintaining manufacturing feasibility.
Solution Approach 2:
The invention changes the temperature parameter by using low-temperature solid phase reaction (below conventional temperatures) to prepare nanoscale precursors, which then enables better morphology control. The two-step process uses different temperature regimes for different stages to achieve both precision and ease of manufacture.
2Reliability
If nanoscale materials are prepared to improve electrochemical performance, then the surface area increases, but the tap density decreases leading to low volumetric energy density
Solution Approach 1:
The invention embeds nanoscale iron-containing oxide particles within the lithium manganese iron phosphate matrix structure. The nanoscale precursors are incorporated during sintering, creating a hierarchical structure where nanoscale active material is nested within the final electrode material, maintaining both high surface area for electrochemical performance and sufficient density for energy density.
Solution Approach 2:
The invention creates a composite structure by combining nanoscale iron-containing oxide with lithium source, manganese source, and phosphorus source materials. This composite approach during sintering produces lithium manganese iron phosphate with controlled morphology that balances electrochemical performance and tap density.
3Quantity of substance
If high tap density is achieved to improve volumetric energy density, then the material packing increases, but the electrochemical performance deteriorates due to reduced surface area
Solution Approach 1:
The invention performs preliminary preparation of nanoscale iron-containing oxide particles with controlled morphology before the final sintering step. This preliminary action creates precursors with optimal surface area and morphology that, when sintered, produce final material with both high tap density and good electrochemical performance, avoiding the need to compromise between the two parameters.
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 results in a lithium manganese iron phosphate positive electrode active material with good electrochemical performance and high tap density, exceeding 1.4 g/cm³, enhancing the volumetric energy density of secondary batteries.
Implementation Method 1
Mixing and grinding an iron source, a solid base and optionally a source of doping element M to allow the components to undergo a low temperature solid phase reaction
Implementation Method 2
granulating by spray drying to obtain a powder
Implementation Method 3
Sintering the powder obtained in S2 to obtain the lithium manganese iron phosphate positive electrode active material
Data Source
AI summary
A lithium manganese iron phosphate positive electrode active material, preparation method, a positive electrode plate, a secondary battery and an electrical apparatus are disclosed. The method comprises: mixing and grinding an iron source, a solid base and optionally a source of doping element M After grinding, impurities are removed to obtain a nanoscale iron-containing oxide; mixing the obtained nanoscale iron-containing oxide with a solvent, a lithium source, a manganese source, a phosphorus source, optionally a source of doping element N, optionally a source of doping element Q and optionally a source of doping element R in a predetermined ratio and then grinding. After grinding, granulating to obtain a powder; and sintering the powder to obtain the lithium manganese iron phosphate positive electrode active material. A lithium manganese iron phosphate positive electrode active material having both good electrochemical performance and high tap density can be obtained.