Lithium Iron Phosphate Doping for Conductivity and Voltage
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Solution Overview
Problem
Current lithium-ion cell positive electrode materials, such as lithium cobalt oxide and lithium manganese oxide, face issues of high manufacturing cost, safety concerns due to radioactivity, and limited capacity, especially under high-temperature conditions, while lithium iron phosphate has low conductivity and limited application in high-power cells.
Innovation Solution
A nano-positive electrode material composed of lithium iron phosphate with conductive and voltage-boosting doping ions, specifically (Li x [M 1-x ])(Fe y [N 1-y ])PO 4, where x and y are within certain ranges, and selected doping ions like Mg 2+, Ti 2+, and Ti 2+, is synthesized through a solid phase reaction process to enhance conductivity and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium cobalt oxide or lithium nickel cobalt oxide is used as positive electrode material, then conductivity and reversibility of lithium ion intercalation-deintercalation are improved, but manufacturing cost increases and safety deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by substituting cobalt with iron in the lithium iron phosphate structure, and adjusts the oxidation state parameter through doping to achieve both safety and conductivity improvements simultaneously
Solution Approach 2:
The patent creates a composite material system by doping lithium iron phosphate with metal ions (Mn3+, Ni2+, Co2+) to combine the safety advantages of iron phosphate with enhanced conductivity, resolving the contradiction between safety and performance
2Object-affected harmful factors
If lithium manganese oxide is used as positive electrode material, then manufacturing cost decreases and safety improves, but capacity and service life cycle deteriorate
Solution Approach 1:
The patent modifies the oxidation state parameter of iron in lithium iron phosphate from +3 to higher states through doping, thereby increasing capacity while maintaining the cost and safety advantages of iron-based materials
Solution Approach 2:
The patent creates a composite structure by incorporating dopant ions into the lithium iron phosphate lattice, forming a multi-element compound that enhances capacity and service life while retaining the inherent safety and cost benefits
3Object-affected harmful factors
If lithium iron phosphate is used as positive electrode material, then manufacturing cost decreases and safety improves, but conductivity deteriorates
Solution Approach 1:
The patent changes the oxidation state parameter of iron from +3 to higher states through doping with metal ions, which significantly enhances electrical conductivity while maintaining the cost and safety advantages of iron phosphate
Solution Approach 2:
The patent creates a composite material by doping lithium iron phosphate with conductive metal ions (Mn3+, Ni2+, Co2+), forming a composite structure that provides both the safety of iron phosphate and the conductivity of transition metal dopants
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 nano-positive electrode material exhibits significantly improved conductivity (10^7 times increase) and discharging voltage (25-22% increase), enabling efficient and safe high-power lithium-ion cell performance.
Implementation Method 1
the conductivity of which is enhanced by 10 7 times and the discharging voltage is boosted by 25-22% through doping
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a nano-positive electrode material of lithium cell and preparation thereof. And the material comprising Lithium iron phosphate as substrate, conductive doping ion and voltage-boosting doping ion, have the general chemical formula: (Lix[M1-x])(Fey[N1-y])PO4, wherein: x=0.9∼0.96 ;y=0.93∼0.97 ; M represents conductive doping ion; N represents voltage-boosting doping ion. The material is prepared by solid phase reaction, of which the process for preparation includes: all raw materials is mixed homogeneously-milled into powder-pellet-formed-isothermally sintered for 2∼3 hours under 200∼400°C in inner atmosphere-cooled-milled into powder-pellet-formed-isothermally sintered for 15∼20 hours under 500∼780°C in inner atmosphere-cooled-milled into powder-airflow grinded and classified. The method is of low production cost, easy to operate, environment friendly and of high yield. The nano-positive electrode material of lithium cell prepared by the solid phase reaction, wherein the conductivity is higher than 10-2S/cm, and the actual discharge capacity > 250mAh/g. And it can be fast charged/discharged in high power. It is provided with the characteristic of low production cost, easy operation method, safety and environment friendly. And it is applicable to small polymer, gel and liquid lithium cell, especially to power cell with high power.