Low-Cobalt Cathode Composite for High-Energy Lithium Batteries
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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 the development of positive electrode active materials.
Innovation Solution
A positive electrode active material comprising first particles of Li a1 Mn z1 Fe x1 A y1 PO 4-c1 and second particles of Li a2 Ni x2 Mn z2 X c2 O 2-b2, with specific elemental compositions and minimal cobalt content, combined with a conductive material and binder, forms the basis of the electrode structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If mixtures of different lithium transition metal oxides are used to achieve high energy density, then energy density is improved, but operating voltage and conductivity may be compromised
Solution Approach 1:
The patent employs composite materials by combining lithium iron phosphate (olivine structure) with lithium nickel manganese oxide (layered structure) in a core-shell configuration. The olivine core provides structural stability and high voltage, while the layered shell enhances capacity and kinetics, achieving both high energy density and high operating voltage simultaneously
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where different regions have different compositions and functions. The core region uses lithium iron phosphate for stability, while the shell region uses lithium nickel manganese oxide for high capacity, allowing each region to optimize its local properties for overall performance
2Power
If mixtures of different lithium transition metal oxides are used to achieve high conductivity, then conductivity is improved, but energy density and operating voltage may be compromised
Solution Approach 1:
The composite structure combines materials with complementary properties: lithium iron phosphate provides structural integrity and voltage stability, while lithium nickel manganese oxide contributes high electronic conductivity and capacity. The synergistic combination achieves high conductivity without sacrificing energy density
Solution Approach 2:
The patent introduces carbon coating as an intermediary layer that enhances electronic conductivity between particles and improves interfacial contact. This conductive network acts as a mediator that enables efficient electron transport while maintaining the high energy density of the active materials
3Quantity of substance
If lithium nickel manganese oxide is used to achieve high capacity, then capacity is improved, but structural stability and lifetime may deteriorate
Solution Approach 1:
The patent creates a composite where lithium nickel manganese oxide (high capacity) is combined with lithium iron phosphate (high stability). The olivine structure of lithium iron phosphate acts as a stable framework that constrains the layered structure, preventing Jahn-Teller distortion and maintaining structural integrity during cycling, thus improving lifetime while preserving high capacity
Solution Approach 2:
By confining lithium nickel manganese oxide to the shell region and lithium iron phosphate to the core, the patent allows the high-capacity material to operate in a localized high-capacity zone while the stable core material provides overall structural support, achieving both high capacity and long cycle life
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 enhances the battery's energy density, operating voltage, and conductivity, resulting in improved performance and efficiency.
Implementation Method 1
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
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AI summary
Positive electrode active materials for a rechargeable lithium battery, positive electrodes including the positive electrode active material, and rechargeable lithium batteries including the positive electrode active material are provided. The positive electrode active material comprises first particles comprising a compound of Lia1Mnz1Fex1Ay1PO4-c1 and second particles comprising a compound of Lia2Nix2Mnz2Xc2O2-b2. The cobalt (Co) content (e.g., amount) in the positive electrode active material is about 100 ppm or less.