Aluminium-Doped Lithium Metal Phosphate for Low-Temperature Resistance
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Solution Overview
Problem
Lithium metal phosphate materials used in secondary lithium ion batteries exhibit reduced electrochemical performance at low temperatures due to increased internal resistance, which is a significant issue for certain battery applications.
Innovation Solution
The use of at least partially agglomerated carbon-coated lithium metal phosphate with a low surface area and aluminium doping, specifically in the form of Lia(Fe1-xMx)PO4, where 0.8≤a≤1.2 and 0≤x≤0.1, and an aluminium content of 300-5000 ppm, significantly reduces internal resistance when incorporated into an electrochemical cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium metal phosphate materials are used, then high power density and good safety profile are achieved, but electrochemical performance is significantly reduced at low temperatures due to increased internal resistance
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition through aluminium doping (300-5000 ppm) and controlling particle morphology (agglomerated secondary particles with BET surface area ≤15 m2/g). These parameter modifications directly reduce internal resistance and improve electrochemical performance at low temperatures while maintaining the base LiFePO4 structure's safety and power density characteristics.
Solution Approach 2:
The invention creates a composite material system combining lithium metal phosphate with aluminium dopant and carbon coating. The aluminium-doped LiFePO4 particles are coated with conductive carbon and formed into agglomerated secondary particles, creating a multi-component composite that synergistically improves low-temperature electrochemical performance while retaining the inherent safety and power density benefits of the base material.
2Reliability
If particles are coated with electrically conductive carbon and produced by conventional processes, then good safety profile is achieved, but electrochemical performance at low temperatures remains reduced
Solution Approach 1:
The patent modifies key parameters including aluminium content (300-5000 ppm), particle surface area (BET ≤15 m2/g through agglomeration), and carbon coating characteristics. These parameter changes are implemented through controlled hydrothermal synthesis and spray drying processes, resulting in materials that maintain the safety benefits of carbon-coated particles while achieving significantly improved low-temperature electrochemical performance through reduced internal resistance.
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 results in improved electrochemical performance at low temperatures by reducing internal resistance and requiring less binder and solvent for electrode formation, enhancing lithium ion conduction and overall battery efficiency.
Implementation Method 1
obtaining lithium metal phosphate from the precursor mixture under hydrothermal conditions
Implementation Method 2
spray drying the mixture
Implementation Method 3
heating the lithium metal phosphate and carbon source to form the carbon-coated lithium metal phosphate
Data Source
AI summary
The present invention provides carbon-coated lithium metal phosphate which is doped with aluminium such that the aluminium content is between 300 and 5000 ppm and which has a BET surface area of less than or equal to 15 m2/g. The carbon-coated lithium metal phosphate finds use as a cathode active material and provides improved electrochemical performance at low temperatures.