Polymer-Ceramic Solid Electrolytes for Stable Li-Ion Anode Interfaces
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Solution Overview
Problem
Current solid-state lithium batteries face issues with interfacial reactivity and dendrite formation due to the use of mixed ionic-electronic conductors and electrochemically unstable inorganic solid electrolytes, leading to high interfacial resistance and internal shorting, which are not effectively addressed by existing protective coating layers.
Innovation Solution
A solid polymer electrolyte (SPE) composed of a polymer backbone, a Li salt, and a salt ionizing plasticizer, such as succinonitrile, with additives like fluoroethylene carbonate, forms a conformal solid-electrolyte interphase (SEI) film that stabilizes the lithium anode and inhibits dendrite growth, using a sandwiched ceramic layer for improved mechanical and electronic insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic solid electrolytes are used to achieve high ionic conductivity, then conductivity is improved, but interfacial reactivity and dendrite formation increase
Solution Approach 1:
The patent employs a composite structure consisting of an inorganic solid electrolyte layer (such as LATP or LAGP ceramics) sandwiched between two polymer electrolyte layers. The inorganic layer provides high ionic conductivity, while the polymer layers form stable solid-electrolyte interphases with the electrodes, preventing interfacial reactivity and dendrite formation. This composite architecture combines the advantages of both material types to resolve the contradiction between conductivity and interfacial stability.
Solution Approach 2:
The polymer electrolyte layers act as intermediary protective layers between the inorganic solid electrolyte and the electrodes. These polymer layers form conformal solid-electrolyte interphases that mediate the interface between the rigid inorganic electrolyte and the flexible electrodes, preventing direct contact and harmful reactions while maintaining efficient ion transport.
2Object-affected harmful factors
If protective coating layers are applied to inorganic solid electrolytes to prevent dendrite formation, then dendrite resistance is improved, but interfacial resistance increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the protective layers by using polymer electrolytes with specific molecular structures and plasticizer compositions. These polymer layers are designed to have optimal mechanical properties (softness and flexibility) and electrochemical properties (ion conductivity and interfacial stability) that allow them to form low-resistance interfaces with electrodes while effectively preventing dendrite penetration, unlike traditional rigid coating layers.
3Reliability
If solid polymer electrolytes with plasticizers are used to achieve high conductivity at room temperature, then conductivity is improved, but electrochemical stability against high-voltage cathodes deteriorates
Solution Approach 1:
The patent applies different functional characteristics to different parts of the electrolyte system. The polymer electrolyte layers containing plasticizers are positioned at the electrode interfaces where high ion conductivity and flexibility are needed, while the inorganic solid electrolyte layer is positioned in the middle where high electrochemical stability and mechanical strength are required. This spatial distribution of properties allows the system to achieve both high conductivity and electrochemical stability.
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 SPE achieves high room temperature conductivity, stable lithium plating/stripping efficiency, and extended cycle life, with full cells demonstrating over 2000 cycles and high current density operation without dendrite formation, and allows for the use of previously incompatible materials in solid-state batteries.
Implementation Method 1
The solid electrolyte needs to be able to conduct ions
Implementation Method 2
the ability to form low-impedance interphases with the anode and the cathode without the need of high stacking pressure
Data Source
AI summary
Solid state batteries having a solid polymer electrolyte (SPE) that replaces a liquid electrolyte between the negative and positive electrode. The SPE is the reaction product of a one-pot polymerization involving a polymer backbone, a Li salt, a plasticizer, and electrolyte additive(s). The electrolyte additive may resolve the anode/electrolyte interfacial corrosive reaction issues to prevent shorting. The negative electrode may be plated with the SPE in the form of an interphase film, which also acts to separate the negative electrode from the positive electrode.