Ceramic Microbattery Electrode Porosity Control
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Solution Overview
Problem
Conventional lithium-ion battery electrodes face challenges in achieving high energy and power density while ensuring safety and long cycle life, due to issues with particle size distribution, porosity, and the use of organic binders which hinder the use of ionic liquids and lead to local charge imbalances and resistive areas.
Innovation Solution
A completely ceramic, mesoporous lithium-ion microbattery electrode is developed without organic binders, featuring homogeneous pore size and porosity between 50% and 25%, achieved by depositing agglomerates of nanoparticles, and coated with an electronically conductive material to enhance conductivity and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional coating techniques with particle sizes of 5-15 μm are used, then the electrode can be manufactured with standard processes, but the volume energy density is limited due to high porosity (40%) and inability to use ionic liquids
Solution Approach 1:
The patent changes the particle size parameter from conventional 5-15 μm to nanometric scale (1-100 nm), which fundamentally alters the electrode properties. This parameter change enables reduced porosity (25-35%), improved volume energy density, and compatibility with ionic liquids while maintaining manufacturability through adapted coating processes
Solution Approach 2:
The patent creates a composite electrode structure by depositing a nanometric active material layer onto a microporous support. This composite architecture combines the high surface area and reactivity of nanoparticles with the mechanical stability and porosity control of the support structure, enabling both high energy density and ionic liquid compatibility
2Quantity of substance
If particle size is reduced to nanometric scale, then volume energy density and specific surface area improve, but manufacturing precision and control of porosity become more difficult
Solution Approach 1:
The patent segments the electrode into two functional components: a nanometric active material layer providing high surface area, and a microporous support structure providing mechanical stability and controlled porosity. This segmentation allows independent optimization of each component's properties while maintaining overall electrode performance
Solution Approach 2:
The microporous support acts as an intermediary between the nanometric particles and the bulk electrode structure. It provides a scaffold that controls macroscopic porosity while allowing the nanoparticle layer to maintain its high surface area, thus mediating between the conflicting requirements of high surface area and controlled porosity
3Reliability
If organic binders are used to compact particles, then electrical contact between particles improves, but ionic liquid impregnation is hindered and local charge imbalances occur
Solution Approach 1:
The patent extracts and eliminates organic binders from the electrode composition entirely. Instead, it relies on direct particle-to-particle contact in the nanometric layer and the conductive microporous support to provide electrical pathways, thereby removing the barrier to ionic liquid impregnation while maintaining electrical connectivity
Solution Approach 2:
The patent employs a microporous support structure with controlled pore size and distribution that facilitates ionic liquid penetration. The porous architecture provides both mechanical integrity and pathways for ion transport, replacing the function previously served by organic binders without their harmful side effects
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 battery with high energy and power density, improved cycling performance, and increased safety due to uniform charge distribution and reduced ion resistance, while eliminating the risk of electrical contact loss and hot spots.
Implementation Method 1
a layer is deposited from said colloidal suspension or paste provided in step (a) on at least one face of said substrate by a method selected from the group formed of: electrophoresis
Implementation Method 2
said layer obtained in step (b) is dried, where appropriate before or after having separated said layer from its intermediate substrate, then, optionally, said dried layer is heat treated, preferably under an oxidising atmosphere, and it is consolidated, by pressing and/or heating
Data Source
AI summary
A method for manufacturing an electrode having a porosity of between 20% and 60% by volume and pores with an average diameter of less than 50 nm. In the method, provision is made of a substrate and a colloidal suspension of aggregates or agglomerates of monodisperse primary nanoparticles of an active electrode material, having an average primary diameter D50 of between 2 and 100 nm, the aggregates or agglomerates having an average diameter D50 of between 50 nm and 300 nm. A layer is deposited from said colloidal suspension on the substrate. The deposited layer is then dried and consolidated to obtain a mesoporous layer. A coating of an electronically conductive material is then deposited on and inside the pores of the porous layer. Such a porous electrode can be used in lithium-ion microbatteries.