MIEC Anode with Open Pores for Alkali Metal Transport
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid-state batteries with alkali metal anodes face issues such as morphological instabilities, electrochemical instability of the solid electrolyte, and mechanical stress-related degradation, leading to reduced performance and reliability, including the formation of insulating debris and electrical shorting.
Innovation Solution
A mixed ionic-electronic conductor (MIEC) with open pores is used to facilitate alkali metal transport, providing a percolated structure that relieves mechanical stresses and maintains contact with the solid electrolyte, while being electrochemically stable and capable of hermetic sealing to prevent fracture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a fully dense Li metal film is used as the anode, then the theoretical gravimetric capacity of 3861 mAh/g is achieved, but morphological instabilities develop during cycling causing the non-Li-metal volume fraction to increase with time
Solution Approach 1:
The patent introduces a porous scaffold structure (such as porous aluminum oxide or porous carbon) that provides a pre-formed three-dimensional network. This scaffold maintains structural integrity during cycling while allowing Li metal to deposit within its pores, preventing the morphological instabilities that occur in fully dense films. The porous structure accommodates volume changes and prevents dendrite formation.
Solution Approach 2:
The patent creates a composite anode structure combining Li metal with a stable scaffold material (such as Al2O3 or carbon). This composite architecture allows the Li metal to provide high capacity while the scaffold provides mechanical stability and prevents morphological degradation during cycling. The composite structure maintains both gravimetric capacity and structural reliability.
2Reliability
If the solid electrolyte is pressed into contact with the moving Li metal front to maintain interface contact, then mechanical contact is maintained, but the solid electrolyte is prone to fracture due to its mechanically brittle nature
Solution Approach 1:
The patent employs a flexible buffer layer (such as a thin metal foil or polymer film) between the solid electrolyte and the Li metal anode. This flexible layer can deform to maintain contact with the moving Li metal front during cycling without transmitting excessive mechanical stress to the brittle solid electrolyte, thereby preventing fracture while maintaining interface contact.
Solution Approach 2:
The patent introduces a buffer layer as an intermediary between the solid electrolyte and the Li metal anode. This buffer layer absorbs mechanical stresses and prevents direct transmission of fracture-inducing forces to the solid electrolyte, while still allowing ionic conduction and maintaining electrical contact throughout cycling.
3Quantity of substance
If the solid electrolyte and Li metal are in direct contact, then ionic conduction occurs, but electrochemical instability results in SEI formation and spalling, creating electrically insulating debris
Solution Approach 1:
The patent introduces a buffer layer (such as a thin metal foil or conductive polymer) as an intermediary between the solid electrolyte and Li metal. This buffer layer forms a stable interface that prevents direct electrochemical reaction between the solid electrolyte and Li metal, eliminating SEI formation and spalling, while maintaining ionic conduction pathways for battery operation.
Solution Approach 2:
The patent uses a sacrificial buffer layer that can be easily replaced or regenerated. This layer absorbs the electrochemical instability effects, forming stable interfaces that protect the solid electrolyte from degradation. The buffer layer serves as a consumable component that maintains system reliability throughout the battery's operational life.
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 MIEC anode design enhances the reliability and performance of solid-state batteries by reducing mechanical stress, preventing electrical shorting, and maintaining ionic and electrical contact, thereby improving the cycle life and safety of the battery.
Implementation Method 1
A mixed ionic-electronic conductor (MIEC) with open pores is used to facilitate alkali metal transport
Implementation Method 2
The open pore structure formed by the MIEC may have sufficient capacity such that when partially filled by the alkali metal
Implementation Method 3
providing a percolated structure that relieves mechanical stresses
Implementation Method 4
capable of hermetic sealing to prevent fracture
Data Source
AI summary
An anode includes a mixed ionic-electronic conductor (MIEC) with an open pore structure. The open pore structure includes open pores to facilitate motion of an alkali metal into and/or out of the MIEC. The open pore structure thus provides open space to relieve the stresses generated by the alkali metal when charging/discharging a battery. The MIEC is formed from a material that is thermodynamically and electrochemically stable against the alkali metal to prevent the formation of solid-electrolyte interphase (SEI) debris and the formation of dead alkali metal. The MIEC may also be passive (the MIEC does not store or release alkali metal). In one example, the open pore structure may be an array of substantially aligned tubules with a width less than about 300 nm, a wall thickness between about 1 nm to about 30 nm, and a height of at least 10 um arranged as a honeycomb.