Multilayer Cathode Structure for Crack-Resistant Lithium Batteries
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Solution Overview
Problem
Lithium metal oxide particles in secondary batteries are prone to cracking during pressing and intercalation/deintercalation, leading to gas generation, reduced lifespan, and performance degradation, especially in high-temperature environments.
Innovation Solution
A cathode active material layer with a multilayer structure comprising first, second, and third lithium metal oxide layers, each with specific thickness and composition ratios, including secondary and single particle forms, to enhance electrochemical stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lithium metal oxide particles in secondary particle form are used, then energy density and charging speed are improved, but cracks occur during pressing and intercalation/deintercalation
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core region and outer shell region have different compositions and properties. The core contains lithium metal oxide particles that provide high capacity, while the shell contains protective coating materials that prevent cracking and maintain particle integrity during charging/discharging cycles. This local differentiation resolves the contradiction by protecting the high-energy-density core material from mechanical stress.
Solution Approach 2:
The patent uses composite materials by combining lithium metal oxide particles with protective coating materials to form a composite cathode active material. This composite structure integrates the high energy density of lithium metal oxide with the mechanical stability and crack resistance of the coating materials, thereby maintaining both high charging speed and particle integrity throughout battery cycling.
2Quantity of substance
If secondary particle structure is used, then energy density is improved, but gas generation increases due to side reactions
Solution Approach 1:
The patent introduces a protective coating layer as an intermediary between the lithium metal oxide particles and the electrolyte. This coating layer acts as a mediator that prevents direct contact and harmful side reactions between the high-energy-density lithium metal oxide and the electrolyte, thereby reducing gas generation while preserving the energy density benefits of the secondary particle structure.
Solution Approach 2:
The patent converts the potential harm of lithium metal oxide particle cracking into a benefit by using the cracking phenomenon as an indicator to develop protective coatings. The coatings are specifically designed to prevent the harmful effects of cracking (gas generation) while maintaining the structural advantages of secondary particles for high energy density.
3Ease of manufacture
If conventional single-layer cathode structure is used, then manufacturing is simple, but electrochemical stability and performance are insufficient
Solution Approach 1:
The patent applies segmentation by dividing the cathode active material into multiple functional layers: an inner core layer containing lithium metal oxide particles for high capacity, and an outer shell layer containing protective coating materials for stability. This segmented structure improves electrochemical stability and performance while maintaining relatively simple manufacturing processes through sequential coating or mixing methods.
Solution Approach 2:
The patent uses the nested doll principle by creating a core-shell structure where the protective coating layer is nested around the lithium metal oxide core particles. This nested configuration allows the smaller functional shell to protect and enhance the performance of the larger capacity-providing core, achieving improved electrochemical stability without significantly complicating the overall cathode structure or manufacturing.
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 multilayer cathode structure improves output characteristics, lifespan, high-temperature storage, and resistance characteristics of lithium secondary batteries.
Implementation Method 1
cracks may occur in the particles due to intercalation and deintercalation of lithium ions during repeated charging and discharging of the lithium secondary battery
Data Source
AI summary
A cathode for a lithium secondary battery according to exemplary embodiments may include: a cathode current collector; and a cathode active material layer formed on the cathode current collector. The cathode active material layer may include: a first cathode active material layer formed on the cathode current collector, and including first lithium metal oxide particles having a form of secondary particles; a second cathode active material layer formed on the first cathode active material layer, and including second lithium metal oxide particles having a form of single particles; and a third cathode active material layer formed on the second cathode active material layer, and including third lithium metal oxide particles having a form of secondary particles.