ZnPS3 Solid Electrolyte With Vacancy-Tuned Divalent Ion Conduction
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Solution Overview
Problem
There is a need for solid-state electrolyte materials that exhibit significant divalent ionic conductivity at room temperature with low activation energy, while being electrically insulating, inexpensive, nontoxic, and electrochemically active, to address the challenges faced by divalent cation-based batteries.
Innovation Solution
The development of solid-state electrolytes characterized by the formula MPS3, where M is one or more metal cations, including divalent cations, with controlled vacancy and ion concentration, enabling divalent ion conductivity and electrical insulation, and optionally incorporating trivalent ions to tune conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If divalent cations (Mg2+, Zn2+) are used instead of monovalent Li+, then two-electron redox processes enable higher energy storage capacity, but solid-state ionic conductivity becomes more difficult due to increased mass and charge density
Solution Approach 1:
The patent modifies the crystal structure parameters of ZnPS3 by substituting Zn2+ with aliovalent cations (Al3+, Ga3+, In3+) to create cation vacancies. This changes the structural parameters (vacancy concentration, lattice spacing) to facilitate Mg2+ ion transport pathways, thereby improving ionic conductivity while maintaining the divalent battery system's high capacity advantage
Solution Approach 2:
The patent creates composite solid electrolyte materials with the formula M1-xAlxPS3 or M1-xGaxPS3, combining divalent metal phosphosulfides with aliovalent cation substitutions. This composite approach simultaneously achieves high divalent ion conductivity and electrical insulation, resolving the contradiction between capacity and conductivity
2Object-affected harmful factors
If solid-state electrolytes are designed for divalent ion conduction, then battery safety is improved by eliminating liquid electrolytes, but achieving significant ionic conductivity at room temperature with low activation energy becomes extremely difficult
Solution Approach 1:
The patent utilizes the layered structure of ZnPS3 with van der Waals gaps that create natural ion transport channels. The layered morphology provides pathways for divalent ion diffusion without requiring high temperatures, achieving room temperature conductivity while maintaining structural integrity and safety
Solution Approach 2:
By introducing aliovalent cation substitutions, the patent changes the electrical and structural parameters of the solid electrolyte, creating cation vacancies that serve as conduction pathways. This reduces the activation energy for ion conduction from typical high values to below 0.5 eV, enabling room temperature operation
3Reliability
If strategies such as metal substitution and lattice softening are applied to maximize Li+ conductivity, then monovalent ion conduction is enhanced, but these approaches are unsuccessful for divalent ions due to differences in charge density
Solution Approach 1:
The patent applies metal substitution specifically at the M2+ sites in ZnPS3, creating localized cation vacancies that are tailored for divalent ion accommodation. This localized modification approach, rather than general lattice softening, creates optimal conditions for Mg2+ or Zn2+ conduction by providing appropriate vacancy sites and maintaining structural stability
Solution Approach 2:
The patent changes the compositional parameter by introducing aliovalent cations (changing x in M1-xAlxPS3), which simultaneously creates cation vacancies and modifies the electronic structure. This parameter change approach is specifically adapted for divalent ions, addressing their higher charge density requirements differently from monovalent Li+ strategies
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 electrolytes achieve divalent ion conductivity at or near room temperature with low activation energy, maintaining electrical insulation, making them suitable for use in electrochemical cells without the need for liquid electrolytes.
Implementation Method 1
First-principles calculations suggest that the barrier corresponds to vacancy-mediated diffusion
Implementation Method 2
the electrolyte is electrically insulating
Data Source
AI summary
In an aspect, an electrochemical cell comprises: a positive electrode; a negative electrode; and a solid state electrolyte in ionic communication with the positive electrode and the negative electrode; wherein: the electrolyte is characterized by formula (FX1): MPS3 (FX1); wherein M is one or more metal cations and optionally metal cation vacancies; and wherein at least one of said one or more metal cations is a divalent cation; the electrolyte is characterized by a divalent ion conductivity; and the electrolyte is electrically insulating. The solid state electrolyte is optionally not an electrocatalyst material or does not function as an electrocatalyst in the electrochemical cell during operation (e.g., charging and/or discharging) of the electrochemical cell. The solid state electrolyte is optionally not an electrode or does not function as an electrode in the electrochemical cell during operation (e.g., charging and/or discharging) of the electrochemical cell.