Na-Doped Carbonate Precursor for Stable Lithium-Rich Cathodes
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Solution Overview
Problem
Current methods for improving the performance of lithium-rich manganese-based positive electrode materials for secondary batteries are either not industrially viable or increase production costs due to complex processes and the need for independent sodium-containing compounds.
Innovation Solution
A manganese-based carbonate precursor with a trace amount of Na is used, which is synthesized through a simple coprecipitation method. This precursor is then mixed with a lithium source and sintered to produce a lithium-rich manganese-based positive electrode material uniformly doped with Na, avoiding uneven doping and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If common modification methods (bulk phase/surface element doping, surface coating, surface structure reconstruction) are used to improve performance of lithium-rich positive electrode material, then initial efficiency and cycling stability are improved, but process complexity increases and production cost increases
Solution Approach 1:
The patent introduces Na element during the coprecipitation process of preparing the manganese-based carbonate precursor, before the material is formed and sintered. This preliminary doping approach eliminates the need for subsequent separate doping steps, surface coatings, or structure reconstruction processes, thereby reducing process complexity while maintaining improved cycling stability and initial efficiency.
Solution Approach 2:
The patent combines the doping function with the precursor synthesis process by introducing Na element during coprecipitation. This merges two separate operations (precursor preparation and doping) into one, simplifying the overall process while achieving uniform Na distribution in the final lithium-rich manganese-based material.
2Reliability
If independent sodium-containing compounds are used as sodium sources for doping, then Na doping is achieved, but production cost increases
Solution Approach 1:
The patent uses Na2CO3 as a dual-purpose reagent: it serves both as the main precipitant for forming the manganese-based carbonate precursor and as the sodium source for doping. This multi-functional use eliminates the need for separate sodium-containing compounds, reducing material costs while achieving the desired Na doping effect.
Solution Approach 2:
The main precipitant (Na2CO3) automatically serves as the sodium source for doping during the coprecipitation process. The system self-regulates the Na content through the stoichiometry of the precipitant, eliminating the need for additional doping agents and reducing production costs.
3Quantity of substance
If high voltage window (≥4.5V vs Li/Li+) is applied to activate lithium-rich phase Li2MnO3, then specific capacity increases to >230 mAhg−1, but structural stability decreases leading to increased capacity attenuation and average discharge voltage attenuation
Solution Approach 1:
The patent introduces Na element at specific locations (substituting for Mn in the layered structure) to locally modify the crystal structure. This local substitution stabilizes the lattice and suppresses the Jahn-Teller distortion and oxygen release that occur during high-voltage cycling, thereby maintaining structural stability while enabling high specific capacity operation.
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 approach significantly improves the initial coulombic efficiency, capacity, average discharge voltage, and cycling stability of the lithium-rich manganese-based positive electrode material, making it more suitable for industrial production while maintaining cost-effectiveness.
Implementation Method 1
a manganese-based carbonate precursor with a trace amount of Na is used, which is synthesized through a simple coprecipitation method
Implementation Method 2
This precursor is then mixed with a lithium source and sintered to produce a lithium-rich manganese-based positive electrode material uniformly doped with Na
Data Source
AI summary
A manganese-based carbonate precursor of a positive electrode material for a secondary battery has a specific structure and composition and contains a trace amount of uniformly distributed Na element, a content of Na is in a range of 0.5-3 mol %, which range can ensure that the structural integrity and consistency of carbonate crystals are not affected. In addition, the trace amount of Na element is uniformly distributed inside the manganese-based carbonate precursor provided in the present application, and by means of simple mixing with a lithium source and sintering, a lithium-rich manganese-based material uniformly doped with Na element can be directly obtained without the need for introducing other Na source, whereby uneven doping of Na is effectively avoided, the doping effect is improved, and the electrical properties of the material are significantly improved.