Lithium Mixed Phosphate Electrode Synthesis via Microwave Solvothermal Process
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Solution Overview
Problem
Current lithium-ion battery electrode materials struggle to achieve high specific capacity and energy density, with existing compounds like LiFePO4 having limited practical capacity and operating potential, necessitating the development of more efficient materials for next-generation lithium batteries.
Innovation Solution
A method for synthesizing lithiated mixed phosphate compounds of the formula LiM1-x-y-z Ny Qz FeX PO4, involving a microwave-assisted solvothermal process with specific precursors and conditions to achieve a compound with high specific surface area and optimal morphology, enhancing conductivity and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiFePO4 is used as electrode material, then safety and stability are improved, but operating potential and specific energy density are limited
Solution Approach 1:
The patent uses composite materials by combining LiFePO4 with carbon coatings and conductive additives to create a composite electrode material that maintains the safety and stability of LiFePO4 while improving electronic conductivity and energy density through the synergistic effects of the different components
Solution Approach 2:
The patent changes physical parameters by controlling particle size reduction to nanoscale dimensions, increasing specific surface area, and optimizing carbon coating thickness to enhance ionic and electronic transport properties, thereby improving operating potential and energy density while preserving the inherent safety of LiFePO4
2Use of energy by moving object
If higher operating potential materials are used, then energy density is improved, but practical specific capacity and electrochemical performance deteriorate
Solution Approach 1:
The patent employs porous structures with controlled porosity to increase the effective surface area for electrochemical reactions, improve electrolyte penetration and ion transport, and provide buffer space for volume changes during cycling, thereby enhancing practical specific capacity while maintaining high operating potential
Solution Approach 2:
The patent segments the electrode material into fine particles or nanostructures, which reduces diffusion path lengths for lithium ions, increases active surface area, and improves electrochemical kinetics, allowing higher practical specific capacity to be achieved at elevated operating potentials
3Ease of manufacture
If conventional synthesis methods are used, then manufacturing simplicity is maintained, but specific surface area and morphology control are insufficient
Solution Approach 1:
The patent uses carbonaceous materials as intermediary substances during synthesis that serve multiple functions: they act as reducing agents, provide carbon coating on particle surfaces, facilitate electron transfer, and control particle morphology, thereby achieving precise surface area and morphology control through a relatively simple one-step synthesis process
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 synthesized compounds demonstrate improved conductivity, low electrochemical polarization, and high specific capacity, potentially leading to higher energy density and stability as positive electrode materials in lithium-ion batteries, addressing the limitations of existing materials.
Implementation Method 1
b) microwave heating of the mixture obtained in step a) at a temperature between 100 and 300 °C, preferably at a temperature of 160 °C and under a pressure between 0.5 and 50 bar
Implementation Method 2
A method for synthesizing lithiated mixed phosphate compounds... involving a microwave-assisted solvothermal process with specific precursors and conditions
Data Source
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AI summary
Producing lithium containing compound (I), comprises (a) mixing precursors and ascorbic acid in an aqueous solvent, preferably glycol compound (consisting of ethylene glycol, diethylene glycol, triethylene glycol and/or tetraethylene glycol), (b) heating the mixture at a temperature of 100-300[deg] C, preferably 160[deg] C and a pressure of 0.5-50 bars, preferably 3 bars for 1-60 minutes, preferably 30 minutes and (c) washing the product with ethanol and water. Producing lithium containing compound of formula (LiM 1 - x - y - zN1 yQ zFe xPO 4) (I), comprises (a) mixing precursors of lithium, M, N, iron, phosphorus and ascorbic acid in an aqueous solvent, preferably glycol compound (consisting of ethylene glycol, diethylene glycol, triethylene glycol and/or tetraethylene glycol), (b) heating the mixture at a temperature of 100-300[deg] C, preferably 160[deg] C and a pressure of 0.5-50 bars, preferably 3 bars for 1-60 minutes, preferably 30 minutes and (c) washing the product with ethanol and water. M : transition element consisting of Co, Ni, Mn or Fe; N1 : doping element different from M and Q, preferably doping element consisting of boron or aluminum and/or a deficiency on the sites of lithium, M, Q, P and/or O; Q : transition element consisting of Co, Ni, Mn or Fe but different from M; x, z : 0-1; and y : 0-0.15, where sum of x+y+z is 0-1. Independent claims are included for: (1) manufacturing a composite material of formula (C-LiM 1 - x - y - zN1 yQ zFe xPO 4) (II), comprises the steps (a)-(c) as above per se, and (d) mixing the compound with carbon powder having a specific surface of greater than 700 m 2>/g; and (2) a lithium containing compound (LiM 1 - x - y - zN1 yQ zFe xPO 4) (I) obtained by the method and having form of platelets whose two dimensions are 20-500 nm and thickness is 1-100 nm.