Solid-State Sodium Battery Catholyte for High-Loading Electrodes
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Solution Overview
Problem
Current all-solid state sodium batteries (SSBs) face challenges in achieving high active material mass loadings, which limits their energy density and operational capacity, particularly due to issues with electrode thickness and soft dendrite formation during charging.
Innovation Solution
The development of a solid-state sodium battery using a positive electrode composed of a compound of formula NaFe x Mn y Ni z O 2, where x, y, and z range from 0 to 1, combined with specific sodium salts and a polymer, allowing for high active material mass loading and improved electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional slurry coating procedure is used, then electrode fabrication is simple, but electrode thickness is limited to 100-200 μm resulting in low areal capacity
Solution Approach 1:
The patent changes the fundamental parameter of electrode fabrication from conventional slurry coating to a new method that enables thickness exceeding 200 μm. This involves modifying the coating procedure parameters including binder-free design, specific drying conditions, and pressing parameters to achieve thick electrodes with good electrochemical performance and mass loading
2Productivity
If high current is used to achieve high loading cathode, then charging speed increases, but soft dendrites form during charging
Solution Approach 1:
The patent introduces a specific electrolyte composition with optimized salt concentration (0.5-2.0 M) and polymer molecular weight (10^5-10^7 g/mol) as an intermediary between the electrode and charging process. This electrolyte mediator enables high current charging by preventing dendrite formation through improved ion transport and electrode interface stability, allowing charging speeds to increase without compromising reliability
3Quantity of substance
If thin electrodes are used, then manufacturing is easier, but areal density and volume density are low resulting in low energy density
Solution Approach 1:
The patent employs composite material strategies by combining specific cathode materials (NaFe0.4Mn0.3Ni0.3O2, Na0.67Fe0.33Ni0.33Mn0.33O2) with optimized binder-free electrode structures and tailored electrolyte compositions. This composite approach enables high active material loading (areal capacity >1.0 mAh·cm^-2) while maintaining structural integrity and electrochemical performance through the synergistic combination of materials
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 battery exhibits enhanced charge/discharge profiles and achieves areal capacities higher than 1.0 mAh·cm^-2, significantly improving the energy density and operational efficiency compared to existing SSBs.
Implementation Method 1
an electrolyte composition; wherein said electrolyte composition comprises a solid sodium-ion conductive composition that conducts sodium ions during use between the negative and the positive electrodes
Implementation Method 2
a positive electrode, said positive electrode comprising a compound of formula NaFe x Mn y Ni z O 2
Data Source
Figure 1
Figure 2a~2b
Figure 2c~2d
AI summary
The invention refers to a solid-state sodium battery comprising a positive electrode compartment comprising a positive electrode, said positive electrode comprising a compound of formula NaFexMnyNizO2, wherein x is more than 0 and equal or less than 1, y is more than 0 and equal or less than 1, and z is more than 0 and less or equal than 1, and wherein said compound is a neutral oxide; and a catholyte, said catholyte comprising a salt of formula NaX, wherein Na is a sodium cation and X is an anion selected from the group consisting of trifluoromethanesulfonyl imide; fluorosulfonyl trifluoromethanesulfonyl imide; and a polymer; a negative electrode compartment comprising a negative electrode, said negative electrode comprising solid metallic sodium or an alloy comprising solid metallic sodium; and an electrolyte composition; wherein the mass loading of the compound of formula NaFexMnyNizO2 is equal or higher than 1.0 mAh cm–2. Moreover, the invention refers a module system which comprises at least two stacked batteries as defined above and to the use of said solid-state sodium battery as an energy storage device.