Pressureless all-solid-state Na/S batteries with self-supporting Na_(5)YSi_(4)O_(12) scaffolds

The development of reliable and affordable all-solid-state sodium metal batteries(ASS-SMBs)requires suitable solid-state electrolytes with cost-efficient processing and stabilized electrode/electrolyte interfaces.Here,an integrated porous/dense/porous Na_(5)YSi_(4)O_(12)(NYS)trilayered scaffold is designed and fabricated by tape casting using aqueous slurries.In this template-based NYS scaffold,the dense layer in the middle serves as a separator and the porous layers on both sides accommodate the active materials with their volume changes during the charge/discharge processes,increasing the contact area and thus enhancing the utilization rate and homogenizing the current distribution.The Na/NYS/Na symmetric cells with the Pb-coated NYS scaffold exhibit significantly reduced interfacial impedance and superior critical current density of up to 3.0 mA cm^(-2)against Na metal owing to enhanced wettability.Furthermore,the assembled Na/NYS/S full cells operated without external pressure at room temperature showed a high initial discharge capacity of 970 mAh g^(-1)and good cycling stability with a capacity of 600 mAh g^(-1)after 150 cycles(based on the mass of sulfur).This approach paves the way for the realization of economical and practical ASS-SMBs from the perspective of ceramic manufacturing.

Stable sodium metal anode enabled by interfacial room-temperature liquid metal engineering for high-performance sodium–sulfur batteries with carbonate-based electrolyte

Sodium(Na)metal is a competitive anode for next-generation energy storage applications in view of its low cost and high-energy density.However,the uncontrolled side reactions,unstable solid electrolyte interphase(SEI)and dendrite growth at the electrode/electrolyte interfaces impede the practical application of Na metal as anode.Herein,a heterogeneous Na-based alloys interfacial protective layer is constructed in situ on the surface of Na foil by self-diffusion of liquid metal at room temperature,named“HAIP Na.”The interfacial Na-based alloys layer with good electrolyte wettability and strong sodiophilicity,and assisted in the construction of NaF-rich SEI.By means of direct visualization and theoretical simulation,we verify that the interfacial Na-based alloys layer enabling uniform Na^(+)flux deposition and suppressing the dendrite growth.As a result,in the carbonate-based electrolyte,the HAIP Na||HAIP Na symmetric cells exhibit a remarkably enhanced cycling life for more than 650 h with a capacity of 1mAh cm^(−2)at a current density of 1mAcm^(−2).When the HAIP Na anode is paired with sulfurized polyacrylonitrile(SPAN)cathode,the SPAN||HAIP Na full cells demonstrate excellent rate performance and cycling stability.