Positive Electrode Active Material for High-Voltage Lithium Batteries
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high operating voltage, and low-temperature performance.
Innovation Solution
A positive electrode active material comprising first and second particles with specific chemical compositions and particle sizes, along with a conductive material and binder, is used to enhance conductivity and stability, resulting in improved energy density and operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single-type positive electrode active material is used, then the electrode structure is simple, but the energy density and operating voltage are limited
Solution Approach 1:
The patent applies composite materials by combining two different positive electrode active materials: a first material with formula Li1+a1□x1Biy1Fe1-y1PO4 and a second material with formula Li1+a2□x2Biz2Fex21-z2PO4. This composite structure enables the electrode to achieve higher energy density and operating voltage by leveraging the complementary properties of both materials, resolving the contradiction between performance improvement and structural simplicity.
Solution Approach 2:
The patent segments the positive electrode active material into two distinct particle types with different chemical compositions and particle diameters. The first particles have diameter D1 and the second particles have diameter D2, where 0.5 ≤ D1/D2 ≤ 2.0. This segmentation allows each material to contribute its specific advantages, achieving high energy density while maintaining a manageable structural complexity through defined compositional ratios.
2Quantity of substance
If particle size is increased to improve capacity, then the energy density improves, but the electrical conductivity decreases
Solution Approach 1:
The patent changes the particle size parameter by controlling the diameter ratio D1/D2 between 0.5 and 2.0, where D1 is the diameter of first particles and D2 is the diameter of second particles. This parameter optimization ensures that particles are not too small (which would limit capacity) nor too large (which would reduce conductivity), thereby resolving the contradiction between capacity and electrical conductivity through precise dimensional control.
3Power
If high voltage operation is pursued to increase energy density, then the operating voltage increases, but the low-temperature performance deteriorates
Solution Approach 1:
The patent uses a composite of two lithium phosphate-based materials with different compositions to achieve high operating voltage (thereby increasing energy density) while maintaining good low-temperature performance. The first material Li1+a1□x1Biy1Fe1-y1PO4 and second material Li1+a2□x2Biz2Fex21-z2PO4 work synergistically, allowing the electrode to operate efficiently across a wide temperature range while achieving the desired high voltage operation.
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 provides rechargeable lithium batteries with enhanced energy density, operating voltage, and low-temperature performance by optimizing the composition and structure of the positive electrode active material.
Implementation Method 1
produces electrical energy through the oxidation and reduction reactions if lithium ions are intercalated into and deintercalated from the positive electrode and negative electrode
Data Source
AI summary
The present application relates to a positive electrode active materials for a rechargeable lithium battery, positive electrodes including the same, and rechargeable lithium batteries including the same. For example, the positive electrode active material includes first particles including a compound of Chemical Formula 1 and having a first average particle diameter, and second particles including a compound of Chemical Formula 2 and having a second average particle diameter that is greater than the first average particle diameter. The content of the first particles is greater than the content of the second particles.