A High‐Performance Monolithic Solid‐State Sodium Battery with Ca²⁺ Doped Na₃Zr₂Si₂PO₁₂ Electrolyte

Abstract

SSEs can effectively avoid short circuit caused by sodium dendrites. [2] Among these SSEs, the Na 3 Zr 2 Si 2 PO 12 (NZSP)type materials meet most of the requirements as promising candidates. Compared with other common sodium ion conductors, such as β-Al 2 O 3 , borate and chalcogenide-based electrolytes, the NZSP shows intermediate densification temperature, wide electrochemical stable windows, high hardness, and high ionic transference number. [3] While, ongoing extensive researches on the NZSP electrolyte-based SSSBs, the low ionic conductivity, and large interfacial resistances between electrodes and electrolytes are the major bottlenecks for their industrial application. After high temperature sintering, the NZSP electrolyte materials always coexist with impurity phase of ZrO 2 and show high grain boundary resistance. [4] The ZrO 2 impurity phase leads to the enrichment of Si and Na elements with generating glassy impurity phase at grain boundary, which shows much lower sodium ionic conductivity, and evidently increases the grain boundary resistance. [5] Thus, it is important to prepare a pure phase NZSP electrolyte with high conductivity (>10 −3 S cm −1 ) to satisfy the requirements of SSSBs.Another challenge hindering the application of SSSBs is the large interfacial resistance between NZSP electrolytes and sodium metal anodes. [6] Sodium metal was proposed to be melted on planar NZSP pellets. However, due to the high surface tension of NZSP ceramics, the melting sodium metal exhibits poor wettability on surface and cannot form a good contact with the electrolyte that results in large interfacial resistances of SSSBs. [7] Additionally, the typical planar SSEs with simple flat surface have limited contact area with sodium metal anodes, and the drastic volume changes of sodium metal anodes during plating and striping would further deteriorate the interface contact. [8] So, the poor solid interface contact, simple interface geometry, and volume change of sodium metal anodes during cycling significantly restrict the application of ceramic electrolytes with sodium metal anodes.To overcome the above-mentioned obstacles, a monolithic all SSSB based on 3D high ion-conductive NZSP-type electrolytes was designed. First, a ZrO 2 -free Ca 2+ doped NZSP electrolyte material was successfully prepared by a sol-gel method. Proper doping strategy with divalent elements at the Zr site of NZSP materials can modulate the lattice parameters, charge carrier Solid-state sodium batteries (SSSBs) are promising electrochemical energy storage devices due to their high energy density, high safety, and abundant resource of sodium. However, low conductivity of solid electrolyte as well as high interfacial resistance between electrolyte and electrodes are two main challenges for practical application. To address these issues, pure phase Na 3 Zr 2 Si 2 PO 12 (NZSP) materials with Ca 2+ substitution for Zr 4+ are synthesized by a sol-gel method. It shows a high ionic conductivity of more than 10 −3 S cm −1 at 25 °C. Moreover, a robus...

Flexible Quasi‐Solid‐State Composite Electrolyte Membrane Derived from a Metal‐Organic Framework for Lithium‐Metal Batteries

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“…[2][3][4][5] Benefiting from intrinsic solid characteristic, solid-state electrolyte can solve the safety issue and inhibit dendrite problem, making it possible for lithium-metal batteries, the "holy grail" of Li-based batteries, whose theoretical specific capacity is about 10 times that of commercial graphite anodes. [3,6] Solid-state electrolytes mainly fall into two kinds, polymerbased electrolytes or inorganic electrolytes. [7,8] For the polymerbased electrolytes, lithium ions can transport along the polymer chains of amorphous region, therefore, the ionic conductivity is determined by the degree of crystallinity.…”

High Voltage, Flexible and Low Cost All‐Solid‐State Lithium Metal Batteries with a Wide Working Temperature Range

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Low‐Operating Temperature, High‐Rate and Durable Solid‐State Sodium‐Ion Battery Based on Polymer Electrolyte and Prussian Blue Cathode

“…However, the insufficient ionic conductivity of SSEs is the main challenge for the further development of SSIBs. During the past years, many kinds of SSEs had been reported including ceramic‐based, sulfide‐based, and polymer electrolytes . Although ceramic‐based solid‐state electrolyte have attracted much attention due to their high ionic conductivity at room temperature, harsh synthetic conditions (for instance, more than 1000 °C and 24 h) and poor contact capability with the electrodes are the main obstacles.…”

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In contrast to the large number of suitable electrode materials, thorough comprehension of the electrolyte remains lacking. [8][9][10][11] Although ceramic-based solid-state electrolyte have attracted much attention due to their high ionic conductivity at room temperature, harsh synthetic conditions (for instance, more than 1000 °C and 24 h) and poor contact capability with the electrodes are the main obstacles. Therefore, the discovery of an effective electrolyte remains a major challenge, which hinders the further application of SIBs.

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