All-Solid-State Cathode Network for Wrinkle-Free Dry Electrode Films
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Solution Overview
Problem
Conventional methods for manufacturing lithium secondary battery electrodes, particularly the dry method, face challenges in achieving uniform shear stress, leading to surface wrinkles and increased surface roughness, which affects the performance of pouch cells but not pressed cells.
Innovation Solution
A cathode for all-solid-state batteries is developed using a network of fibrous carbon materials with specific properties, including a first layer of fibrous carbon materials and a second layer with active materials, where fibrillized polytetrafluoroethylene (PTFE) is used as a binder to prevent surface wrinkles and enhance surface smoothness through uniform shear stress application during film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the wet method is used to manufacture electrodes, then the electrode can be manufactured with a binder, but it becomes difficult to dry the electrode as the electrode becomes thicker and an excessive amount of binder is deposited on the surface
Solution Approach 1:
The invention extracts the binder component from the traditional slurry composition and replaces it with a dry powder mixture of active material, conductive carbon, and dispersant. This eliminates the need for drying processes while maintaining electrode integrity, as the binder is completely removed from the system rather than just reduced.
2Ease of manufacture
If the conventional dry method is used to manufacture electrodes, then the electrode can be manufactured without drying, but the shear stress is not sufficient nor uniformly transmitted, resulting in surface wrinkles
Solution Approach 1:
The invention changes the physical state parameters of the starting materials from powder to granulated form with controlled particle size distributions. This granulation process creates uniform stress distribution during compression, enabling sufficient and uniform shear stress transmission that prevents surface wrinkles while maintaining the dry manufacturing advantage.
Solution Approach 2:
The invention creates a composite granulated material system combining active material, conductive carbon, and dispersant in specific ratios and particle size distributions. This composite structure ensures uniform stress transmission during compression while maintaining electrical conductivity and preventing surface defects, resolving the contradiction between ease of manufacture and manufacturing precision.
3Use of energy by moving object
If the electrode is thickened to increase energy density, then the energy density increases, but the surface wrinkles and surface roughness increase
Solution Approach 1:
The invention performs preliminary granulation of the starting materials before electrode compression, creating uniformly sized granules with controlled properties. This preliminary action ensures that when the electrode is compressed to increased thickness for higher energy density, the stress is uniformly distributed throughout the structure, preventing surface wrinkles and maintaining low surface roughness even at greater thicknesses.
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 results in a cathode with no surface wrinkles and low surface roughness, improving the mechanical properties and performance of all-solid-state batteries, specifically enhancing charge capacity, retention capacity, and Coulombic efficiency.
Implementation Method 1
a plurality of fibrous carbon materials form a network including pores such that the first active material is disposed in pores of the network
Implementation Method 2
an electrode may maintain the form of a membrane by fibrillizing a suitable binder by applying shear stress to powder including an active material, the binder, or the like
Data Source
AI summary
Disclosed are a cathode for all-solid-state batteries including a network, and a method of manufacturing the same.