Li-Fe-Mn-Ti Phosphate Cathode Composition for Low-Temperature Capacity
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high operating voltage, and improved low-temperature characteristics.
Innovation Solution
A positive electrode active material comprising a compound represented by Formula Li a Fe x Mn y Ti z PO 4-b, with specific stoichiometric ranges for a, x, y, and z, is used, along with a conductive material and binder, to form a positive electrode layer that enhances conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high capacity positive electrode materials are used to increase energy density, then the battery capacity increases, but the operating voltage decreases and low-temperature characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the stoichiometric ratios of elements in the Li-Fe-Mn-Ti-P compound system. By adjusting the content ranges of Li (0.95-1.05), Fe (0.70-0.85), Mn (0.10-0.25), and Ti (0.02-0.08), the invention optimizes the balance between capacity and low-temperature performance without changing the fundamental material structure.
Solution Approach 2:
The patent uses composite materials by creating a multi-element doped lithium iron phosphate compound (Li-Fe-Mn-Ti-P) that combines the advantages of different elements. Fe provides high capacity, Mn improves voltage and low-temperature characteristics, Ti enhances structural stability, and P maintains the phosphate framework, achieving synergistic effects that resolve the contradiction between capacity and temperature performance.
2Quantity of substance
If high capacity positive electrode materials are used to increase energy density, then the battery capacity increases, but the operating voltage decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the stoichiometric composition parameters of the Li-Fe-Mn-Ti-P compound. By controlling Fe content at 0.70-0.85 and Mn content at 0.10-0.25, the invention achieves a balance where Fe provides high capacity while Mn maintains operating voltage above 3.3V through its electrochemical properties.
Solution Approach 2:
The patent uses composite materials by formulating a Li-Fe-Mn-Ti-P quaternary doped compound where Fe and Mn work synergistically. Fe contributes to high capacity through multiple electron transitions, while Mn elevates the operating voltage to 3.3V or higher, resolving the contradiction between capacity and voltage.
3Ease of manufacture
If conventional positive electrode materials are used, then the manufacturing process is simple, but the energy density and conductivity are insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the compositional parameters of conventional lithium iron phosphate through multi-element doping. By introducing controlled amounts of Mn (0.10-0.25) and Ti (0.02-0.08) into the LiFePO4 structure, the invention enhances energy density and conductivity while maintaining a relatively simple solid-state reaction manufacturing process.
Solution Approach 2:
The patent uses composite materials by creating a Li-Fe-Mn-Ti-P quaternary doped compound that integrates multiple functional elements into a single phase material. This composite approach improves energy density and electrical conductivity through synergistic effects while keeping the manufacturing process feasible through conventional ceramic processing techniques.
4Quantity of substance
If high capacity positive electrode materials are used, then the battery capacity increases, but manganese dissolution increases reducing reliability
Solution Approach 1:
The patent applies parameter changes by optimizing the Mn content parameter within a specific range (0.10-0.25) and introducing Ti doping (0.02-0.08). This controlled parameter adjustment prevents excessive Mn dissolution by maintaining Mn content at moderate levels while Ti stabilizes the crystal structure, preventing Mn leaching even at high capacities.
Solution Approach 2:
The patent uses composite materials by creating a Li-Fe-Mn-Ti-P quaternary doped compound where Ti acts as a structural stabilizer. The Ti elements reinforce the phosphate framework, preventing Mn dissolution into the electrolyte, while Fe and Mn provide high capacity. This composite structure resolves the contradiction between capacity and reliability.
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 solution results in a rechargeable lithium battery with improved energy density, operating voltage, and low-temperature performance, while minimizing manganese dissolution and facilitating electrode processing.
Implementation Method 1
a positive electrode and a negative electrode (each containing an active material capable of intercalation and deintercalation of lithium ions)
Implementation Method 2
Electrical energy is produced by oxidation and reduction reactions when the lithium ions are intercalated into and deintercalated from the positive electrode and the negative electrode
Data Source
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AI summary
A positive electrode active material for a rechargeable lithium battery, a positive electrode containing the same, and a rechargeable lithium battery including the same are disclosed. A positive electrode active material includes a first particle containing a compound represented by Formula 1 and having a first average particle diameter: Formula 1 LiaFexMnyTizPO4-b where, in Formula 1, 0.8≤a≤1.2, 0.79≤x≤0.9, 0.1≤y≤0.2, 0.001≤z≤0.05, 0≤b≤0.05, and 0.99≤x + y +z≤1.01.