Composite Cathode Material for Low-Temperature Li-Ion Performance
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high operating voltage, and high conductivity, particularly in low-temperature conditions.
Innovation Solution
A positive electrode active material comprising first particles with an olivine structure and second particles with a spinel structure, where the amount of first particles exceeds the second particles, and both types are doped with specific elements to enhance conductivity and stability, thereby forming a positive electrode active material layer with improved electrical conductivity and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material with high energy density is used, then the battery capacity increases, but the operating voltage and conductivity may be compromised
Solution Approach 1:
The patent employs a composite material system consisting of olivine-structured LiFe1-x-yMnxP1-yO4 (first particles) and spinel-structured LiMn2-yEyO4 (second particles). This composite structure combines the high voltage characteristics of spinel materials with the high capacity properties of olivine materials, achieving both high operating voltage (3.7-4.0V) and high energy density (430-500 Wh/kg) simultaneously.
Solution Approach 2:
The patent applies local quality enhancement through doping with specific elements (Ti, V, Nb in olivine; Mg, Al in spinel) at controlled concentrations (0.001≤z1≤0.05 for olivine dopant, 0≤y2≤0.05 for spinel dopant). This localized modification improves electrical conductivity in specific regions of the composite material without compromising the overall structural stability and voltage characteristics.
2Ease of manufacture
If conventional positive electrode materials are used, then manufacturing is straightforward, but low-temperature performance and conductivity are insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the positive electrode active material by controlling the ratios of Mn, Fe, and dopant elements (0.5≤x1≤0.9, 0.1≤y1≤0.5, 0.001≤z1≤0.05 for olivine; 1.9≤x2≤2.05, 0≤y2≤0.05 for spinel). These parameter adjustments optimize electrical conductivity and ion transport properties, enabling reliable operation at low temperatures while maintaining ease of manufacture through conventional solid-state reaction methods.
3Reliability
If cobalt is used to improve conductivity and capacity, then performance increases, but cost increases significantly
Solution Approach 1:
The patent replaces expensive cobalt with abundant and cost-effective elements such as Mn, Fe, Ti, V, Nb, Mg, and Al. The composite material system achieves acceptable conductivity through doping strategies using these cheaper elements, significantly reducing material costs while maintaining functional performance. For example, doping with Ti, V, or Nb at 0.001-0.05 mol ratio provides sufficient conductivity enhancement without cobalt.
Solution Approach 2:
The patent optimizes the compositional parameters of cobalt-free materials to achieve desired conductivity. By adjusting the doping concentrations (0.001≤z1≤0.05 for olivine, 0≤y2≤0.05 for spinel) and the Mn/Fe ratios (0.5≤x1≤0.9, 0.1≤y1≤0.5), the material achieves adequate electrical conductivity and capacity without relying on cobalt, thereby reducing costs while maintaining performance.
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 enhanced energy density, operating voltage, and low-temperature performance, while minimizing the use of cobalt to reduce costs and improve capacity.
Implementation Method 1
A rechargeable lithium battery produces electrical energy through the oxidation and reduction reactions when lithium ions are intercalated into and deintercalated from the positive electrode and negative electrode
Data Source
AI summary
Disclosed are positive electrode active materials for a rechargeable lithium battery, positive electrodes including the positive electrode active materials, and rechargeable lithum batteries including the positive electrode active materials. The positive electrode active material comprises first particles comprising a compound having an olivine structure, and second particles having a spinel structure. The amount of the first particles is greater than the amount of the second particles.