Borohydride-Sulfide Two-Layer Electrolyte for Solid-State Battery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
All-solid-state batteries face compatibility issues between solid electrolytes and lithium metal anodes and high-voltage cathodes, leading to lithium dendrite formation and interface impedance problems, which hinder their large-scale commercial application.
Innovation Solution
An all-solid-state lithium battery design utilizing a two-layer electrolyte composed of a borohydride fast ion conductor and a sulfide fast ion conductor, with the cathode positioned on the sulfide layer and the anode on the borohydride layer, to enhance compatibility and stability, allowing for high working voltage and long cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide solid electrolyte is used, then ionic conductivity is improved, but interface stability with lithium metal anode deteriorates
Solution Approach 1:
The electrolyte is segmented into two distinct layers: a sulfide-based fast ion conductor layer (close to cathode) and a borohydride-based stable layer (close to anode). This segmentation allows each layer to perform its specialized function - the sulfide layer provides high ionic conductivity while the borohydride layer ensures interface stability with lithium metal, resolving the contradiction between conductivity and stability.
Solution Approach 2:
The borohydride-based layer acts as an intermediary between the sulfide electrolyte and lithium metal anode. It mediates the interface interaction, preventing direct contact between sulfide and lithium that would cause instability, while still maintaining ionic conductivity through the layered structure.
2Reliability
If buffer layer is introduced at cathode/sulfide interface, then interface impedance is reduced, but device complexity increases
Solution Approach 1:
The buffer layer function is merged into the second electrolyte layer itself. The borohydride-based layer serves dual purposes: it maintains interface stability with lithium metal while also acting as the buffer layer at the cathode interface. This merging eliminates the need for separate buffer layers, reducing device complexity while maintaining low interface impedance.
3Stability of the object's composition
If Li-In alloy is used as anode, then interface stability is improved, but energy density is reduced
Solution Approach 1:
The borohydride-based electrolyte layer acts as an intermediary that enables direct use of high-capacity lithium metal anode instead of Li-In alloy. It provides the necessary interface stability and dendrite suppression, allowing lithium metal's full theoretical capacity to be utilized without forming low-voltage alloy anodes, thus maintaining high energy density.
4Reliability
If garnet-type solid electrolyte is used, then ionic conductivity is improved, but mechanical deformability deteriorates
Solution Approach 1:
The invention changes the material parameters by selecting borohydride-based compounds with inherently better mechanical deformability while maintaining high ionic conductivity. This parameter change allows the electrolyte to accommodate volume expansion of electrodes and suppress dendrite growth through elastic deformation, overcoming the brittleness of garnet-type electrolytes.
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 borohydride/sulfide two-layer fast ion conductor configuration achieves high working voltage and excellent cycle stability, addressing the compatibility issues and enabling suitable large-scale commercial production.
Implementation Method 1
inorganic solid electrolytes, represented by lithium lanthanum zirconium oxide and lithium germanium phosphorus sulfide, are greatly improved in ionic conductivity which is up to 10−3 to 10−2 S cm−1 at room temperature
Implementation Method 2
using inorganic solid electrolytes with high mechanical strength to prepare all-solid-state lithium batteries will not only solve the safety problems of the organic liquid electrolyte, but also suppress the dendritic lithium growth
Implementation Method 3
borohydride, as a new type of solid electrolyte material, is stable to lithium due to its strong reducibility, and has a low grain boundary impedance and a high mechanical deformability
Implementation Method 4
If a buffer layer is introduced at the cathode/sulfide solid electrolyte interface, the space charge layer and element interdiffusion can be suppressed so as to reduce the interfacial impedance
Implementation Method 5
the space charge layer and element interdiffusion can be suppressed so as to reduce the interfacial impedance
Implementation Method 6
borohydride, as a new type of solid electrolyte material, is stable to lithium due to its strong reducibility
Implementation Method 7
sulfide solid electrolytes are unstable to lithium metal and will be reduced by lithium to form an interface layer after contacting with lithium
Data Source
AI summary
The present invention discloses a preparation method of an all-solid-state lithium battery based on borohydride/sulfide two-layer fast ion conductors, comprising the steps of: Step 1: cold-pressing a borohydride fast ion conductor and a sulfide fast ion conductor into a two-layer electrolyte; Step 2: mixing a cathode active material, a sulfide fast ion conductor, and a conductive agent according to a ratio to prepare a cathode of the all-solid-state lithium battery, and cold-pressing the cathode onto a side, corresponding to the sulfide fast ion conductor, of the two-layer electrolyte obtained in Step 1; and taking a lithium metal plate as an anode of the all-solid-state lithium battery, and cold-pressing the anode onto a side, corresponding to the borohydride fast ion conductor, of the two-layer electrolyte obtained in Step 1; and Step 3: packaging a material obtained in Step 2 to obtain the all-solid-state lithium battery based on borohydride/sulfide two-layer fast ion conductors. According to the present invention, an all-solid-state battery with high working voltage and good cycle performance is achieved, and the preparation process is simple and has good repeatability, thereby being suitable for large-scale commercial production.