Double-Layer Cathode Rolling for Stable Lithium Secondary Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium secondary batteries face challenges with low electrical performance and structural instability due to the use of irreversible additives like Li6CoO4, which are structurally unstable and generate oxygen gas, leading to electrode expansion and increased electrical resistance, limiting high-speed charging and discharging capabilities.
Innovation Solution
A positive electrode for lithium secondary batteries with a double-layer structure, comprising a first mixture layer with 15-40% porosity and a second mixture layer with 40-70% porosity, using specific lithium cobalt oxide additives and lithium nickel composite oxides, controlled through precise rolling operations to enhance structural stability and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a cathode is washed with water or an organic solvent during manufacturing, then residual solvent is removed, but structural stability deteriorates due to crystal structure transformation or aggregate formation
Solution Approach 1:
The patent extracts and removes the harmful washing step entirely from the manufacturing process. By using a solvent-free drying method, the cathode material is dried without contact with water or organic solvents, thereby eliminating the source of structural transformation and aggregate formation while still achieving residual solvent removal through alternative means.
Solution Approach 2:
The patent introduces a drying agent as an intermediary substance that absorbs residual solvents from the cathode material without causing structural damage. This mediator enables solvent removal while maintaining the integrity of the cathode's crystal structure, avoiding the harmful effects of direct water or solvent washing.
2Productivity
If a cathode is dried at high temperature, then drying efficiency is improved, but structural stability deteriorates due to crystal structure transformation
Solution Approach 1:
The patent changes the drying parameters by using low temperature (below 100°C, preferably room temperature) combined with extended drying time and controlled humidity conditions. This parameter modification maintains drying efficiency while preventing the thermal energy from causing crystal structure transformation or aggregate formation in the cathode material.
Solution Approach 2:
The patent employs periodic or extended drying cycles at low temperature rather than a single high-temperature step. This prolonged, gentle drying approach allows gradual moisture removal without subjecting the cathode structure to sudden thermal stress that would cause transformation or aggregation.
3Object-generated harmful factors
If a cathode is washed with water, then cleanliness is improved, but structural stability deteriorates due to phase transformation from monoclinic to triclinic
Solution Approach 1:
The patent creates an inert drying environment using desiccants or controlled humidity conditions that prevent water from interacting with the cathode material. This inert environment allows for effective cleaning and drying without exposing the moisture-sensitive cathode to water that would trigger monoclinic-to-triclinic phase transformation.
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 double-layer structure improves electrical performance and structural stability, increasing charging capacity, reducing irreversible capacity, and enhancing the battery's lifetime characteristics by controlling the rolling conditions and porosity of the mixture layers.
Implementation Method 1
drying with a drying agent
Data Source
AI summary
The present technology relates to 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.