Stable All‐Solid‐State Na Batteries Enabled by In Situ Formed Na─B─H─F Electrolyte

Abstract

All‐solid‐state Na‐ion batteries are considered to be one of the most promising candidates for large‐scale applications at low‐cost. Hydride electrolytes have been pursued as a research hotspot more recently, owing to their high Na‐ion conductivities, while there is an urgent need to address their electrochemical stabilities in order to meet the requirements for applications in Na batteries. Herein, a novel and universal strategy is proposed to improve the electrochemical stabilities of hydride electrolytes, which takes advantage of the in situ reactions between hydrides and NaHF2. As a representative example, Na2B12H12 can react with NaHF2 to form NaF nanoparticles that are uniformly embedded in the Na2B12H11F matrix, which exhibits superior electrode compatibilities without apparent reduction in conductivity. The symmetrical Na cell thus derived shows a long‐term cycling and the quasi‐symmetrical Na3V2(PO4)3 cell shows high Coulombic efficiency. They give rise to a stable cycling of the Na||Na3V2(PO4)3 all‐solid‐state batteries with a capacity retention of 87.7% after 100 cycles, which can be attributed to the stabilization of electrolyte/electrode interfaces by the F‐enriched interphases. Beyond Na batteries, the present study sheds timely new light on the development of hydride electrolytes for other long‐waited applications.

Status and strategies of electrolyte engineering for low-temperature sodium-ion batteries

“…Also, the fluorine doping strategy was proven to be effective. 97 By adding sodium fluoride salt, it was decomposed into fluorine SEI at the electrode interface, which jointly played the dual role of preventing further side reactions and rapid ion conduction, and the interface stability of the fluorinated electrolytes was greatly increased. As a result, an almost 99% retention rate at 3C was presented at −20 °C.…”

Co-doping strategies for advanced solid state electrolytes with lithium salt: a study on the structural and electrochemical properties of LATP

“…Hydride-based SSE represents an alternative category that incorporates hydrogen-terminated anions. However, these electrolytes encounter several challenges, including limited material availability, pronounced chemical reactivity, and sensitivity to temperature [7]. Borohydride-based SSEs, a subtype of hydride electrolytes, represented by LiBH 4 -LiCl-P 2 S 5 composites, exhibit enhanced Li-ion conduction under nanoconfinement and demonstrate favorable wetting properties.…”