Layered Cathode Active Material for High-Voltage Li-Ion Battery Life
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high average voltage, and excellent lifetime while maintaining economic viability.
Innovation Solution
A positive electrode active material comprising a combination of olivine-structured and spinel-structured lithium compounds, where the first particle includes a compound represented by Formula 1 and the second particle includes a compound represented by Formula 2, with specific elemental compositions and structures, is used to enhance the performance of rechargeable lithium batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single positive electrode active material is used, then the electrode structure is simple, but the energy density and average voltage cannot be simultaneously optimized
Solution Approach 1:
The patent combines two different positive electrode active materials (first and second particles with different compositions and structures) into a single electrode, merging their complementary properties to achieve both high energy density and high average voltage while maintaining a relatively simple electrode structure
Solution Approach 2:
The patent uses a composite material system where two distinct active materials with different chemical compositions and crystal structures are integrated in the positive electrode, allowing simultaneous optimization of energy density and voltage characteristics
2Quantity of substance
If high capacity active materials are used, then energy density increases, but lifetime deteriorates
Solution Approach 1:
The patent applies local quality by assigning different functional roles to different particles: the first particle provides high capacity while the second particle provides structural stability and long cycle life, with each material optimized for its specific function in the composite system
Solution Approach 2:
The composite material system combines a high-capacity active material with a structurally stable active material, where the latter protects and supports the former during cycling, thereby achieving both high capacity and extended lifetime
3Quantity of substance
If high average voltage is pursued, then energy density improves, but lifetime decreases
Solution Approach 1:
The patent uses local quality by placing the high-voltage active material in specific regions or combinations with lower-voltage but more stable materials, allowing the electrode to achieve high average voltage while the stable material compensates for voltage-induced degradation
Solution Approach 2:
The composite material system integrates high-voltage active materials with structurally robust materials that can withstand high voltage operation, thereby maintaining both high average voltage and extended 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 proposed electrode material achieves high energy density, high average voltage, and improved lifetime characteristics, while being economical, by utilizing a layered structure with olivine and spinel compounds that provide enhanced lithium ion intercalation and deintercalation capabilities.
Implementation Method 1
a positive electrode and a negative electrode, each including an active material that allows intercalation and deintercalation of lithium ions
Implementation Method 2
produce electrical energy from redox reactions that take place as lithium ions are intercalated into or deintercalated from the positive electrode and the negative electrode
Data Source
AI summary
Provided are a positive electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same, and for example, a positive electrode, including a current collector, a first positive electrode active material layer on the current collector, and a second positive electrode active material layer on the first positive electrode active material layer. The first positive electrode active material layer includes a first particle including a compound represented by Formula 1 and having an olivine structure, and a second particle including a compound represented by Formula 2 and having a spinel structure, and the second positive electrode active material layer includes a third particle including a compound represented by Formula 3 and having an olivine structure. The first particle is a positive electrode for a rechargeable lithium battery in the form of a secondary particle in which a plurality of primary particles are aggregated.