LiMnPO4 Cathode Material via Coprecipitation for High Capacity
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Solution Overview
Problem
Current cathode active materials for lithium secondary batteries, such as lithium cobalt oxide, spinel-type lithium manganese oxide, and lithium composite metal oxide, face issues with stability, safety, and capacity, particularly in large-sized batteries, while lithium manganese phosphate compounds exhibit poor electrochemical properties and low capacity when prepared using existing methods.
Innovation Solution
A method involving a coprecipitation process to form a highly crystalline nano-sized LiMnPO4 material, combined with an electrochemically inactive Li2MnO3-based cathode material, through steps including hydrate precursor preparation, synthetic powder preparation, oxide material powder preparation, composite powder mixing, and slurry formation with a conductor and binder, to enhance reversible properties and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium manganese phosphate compound is prepared by conventional methods (precipitation and reduction of Mn(OH)2 or spray drying), then the material can be obtained, but the electrical capacity is very low (40-92 mAh/g) and electrochemical properties are poor
Solution Approach 1:
The patent changes the preparation parameters by using coprecipitation method instead of conventional precipitation, controlling pH range (6.5-11.5), temperature (20-100°C), and aging time (1-72 hours) to obtain highly crystalline nano-sized LiMnPO4 material with superior electrochemical properties and electrical capacity of 120-160 mAh/g
Solution Approach 2:
The patent creates a composite cathode material by mixing nano-sized LiMnPO4 with Li2MnO3-based cathode material, combining the high capacity of LiMnPO4 with the structural stability of Li2MnO3 to achieve both high electrical capacity and good electrochemical properties
2Use of energy by moving object
If lithium cobalt oxide (LCO) is used as cathode active material, then high energy density is achieved, but stability problems occur making it unsuitable for large-sized batteries
Solution Approach 1:
The patent develops a composite cathode material containing LiMnPO4 and Li2MnO3 that combines the high energy density characteristics with improved stability, making it suitable for large-sized lithium secondary batteries while maintaining electrochemical performance
3Temperature
If spinel-type lithium manganese oxide (LMO) is used, then thermal stability is excellent, but manganese dissolves when battery temperature increases to about 60°C
Solution Approach 1:
The patent creates a composite material where Li2MnO3 provides structural stability and prevents manganese dissolution at elevated temperatures, while LiMnPO4 contributes high capacity, achieving both thermal and structural stability
4Quantity of substance
If lithium iron phosphate compound (LiFePO4) is used, then superior electrical capacity is achieved, but discharge voltage (3.2-3.4 V) is lower than oxide-based materials
Solution Approach 1:
The patent uses coprecipitation method to prepare highly crystalline nano-sized LiMnPO4 material with improved electrochemical properties and electrical capacity of 120-160 mAh/g at discharge voltage of 3.8-4.0 V, matching oxide-based materials while maintaining high capacity
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 resulting cathode active material demonstrates superior reversible properties and high capacity, with energy densities ranging from 551 Wh/g to 718 Wh/g, suitable for medium- or large-sized lithium secondary batteries.
Implementation Method 1
a hydrate precursor preparation step of preparing a manganese phosphate hydrate precursor using a coprecipitation process
Implementation Method 2
an oxide material powder preparation step of preparing a lithium manganese phosphate oxide material powder by milling and annealing the synthetic powder
Data Source
AI summary
Disclosed is a method of preparing a cathode electrode material for a secondary battery, including a hydrate precursor preparation step of preparing a manganese phosphate hydrate precursor using a coprecipitation process, a synthetic powder preparation step of preparing a synthetic powder by mixing the manganese phosphate hydrate precursor in a powder form with lithium phosphate and carbon, an oxide material powder preparation step of preparing a lithium manganese phosphate oxide material powder by milling and annealing the synthetic powder, a composite powder preparation step of preparing a composite powder by mixing the lithium manganese phosphate oxide material powder with a Li2MnO3-based cathode material, and a slurry preparation step of preparing a slurry by mixing the composite powder with a conductor and a binder.