Double-Layer Cathode Structure for Conductivity and Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges with low electrical performance and structural instability due to the use of conventional irreversible additives like Li6CoO4, which exhibit low powder electrical conductivity and structural instability, leading to reduced charging/discharging capacity and battery degradation.
Innovation Solution
A positive electrode with a double-layer structure is developed, comprising a first mixture layer with a lithium cobalt oxide additive and a second mixture layer, optimized for porosity and thickness, to improve electrical properties and structural stability, using a manufacturing method that controls rolling conditions to minimize additive degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional irreversible additive Li6CoO4 is used in the positive electrode, then lithium consumption during initial charging is reduced, but the positive electrode exhibits low powder electrical conductivity and structural instability
Solution Approach 1:
The patent applies composite materials by combining Li6CoO4 irreversible additive with conductive carbon materials (acetylene black, Ketjen black, or graphite) in the positive electrode mixture. This composite structure maintains the lithium reservoir function of Li6CoO4 while the carbon component provides electrical conductivity pathways, resolving the contradiction between irreversible capacity loss reduction and electrical conductivity maintenance
Solution Approach 2:
The conductive carbon material acts as an intermediary between the insulating Li6CoO4 particles and the current collector/electrolyte. This intermediary component enables electrical charge transfer while allowing Li6CoO4 to perform its lithium consumption function, thus mediating between the conflicting requirements of low conductivity and high reliability
2Reliability
If conventional irreversible additive Li6CoO4 is used in the positive electrode, then lithium consumption during initial charging is reduced, but structural instability occurs during charging/discharging
Solution Approach 1:
The patent creates a composite structure where Li6CoO4 is combined with structurally stable carbon materials and binder components. The carbon matrix and binder provide structural stability during charging/discharging cycles while Li6CoO4 maintains its lithium reservoir function, thus resolving the contradiction between reliability improvement and structural stability
Solution Approach 2:
The binder component forms a flexible matrix that accommodates volume changes of Li6CoO4 particles during charging/discharging. This flexible binding structure prevents structural degradation while allowing the irreversible additive to function, thus maintaining both reliability and structural stability
3Ease of manufacture
If conventional irreversible additive with low powder electrical conductivity is used, then manufacturing complexity is reduced, but charging/discharging capacity decreases at high C-rate
Solution Approach 1:
The patent combines simple-to-manufacture Li6CoO4 additive with conductive carbon materials in a slurry formulation that can be applied using conventional coating methods. The composite mixture maintains ease of manufacture while the carbon component ensures high electrical conductivity for fast charging/discharging performance
Solution Approach 2:
The patent optimizes parameters including the ratio of Li6CoO4 to conductive carbon (0.1-5 wt% Li6CoO4), slurry composition, drying temperature (60-100°C), and pressing conditions. These parameter adjustments maintain manufacturing simplicity while achieving high conductivity and capacity at various C-rates
Data Source
AI summary
Provided is a positive electrode for a lithium secondary battery with improved structural stability, a manufacturing method thereof, and a lithium secondary battery including the same. When the positive electrode containing a positive electrode additive is manufactured, the conditions of first and second rolling operations are controlled so that there is an advantage in that structures and electrical properties of a first mixture layer and a second mixture layer can be improved.