Unraveling the Conversion Evolution on Solid‐State Na–SeS₂ Battery via In Situ TEM

Abstract

All‐solid‐state (ASS) Na–S batteries are promising for a large‐scale energy‐storage system owing to numerous merits. However, the high conversion reaction barrier impedes their practical application. In this work, the basic mechanism on how Se catalyzes the conversion reaction in the Na–S batteries is unraveled. The sodiation/desodiation of Na–SeS2 nanobatteries are systematically evaluated via in situ transmission electron microscopy (in situ TEM) with a microheating device. The real‐time analyses reveal an amorphous Na–SexSy intermediate phase appears during the direct conversion from SeS2 to Na2S, and a reverse reaction succeeds at 100 °C with a prior formation of Se. The absence of polysulfides and a much lower desodiation temperature in contrast to Na–S nanobatteries demonstrate that the Se incorporation significantly lowers the conversion reaction barrier. According to these findings, the ASS SeS2 batteries using a Na3SbS4 solid electrolyte (SE) are assembled using various SE:C ratios in the composite cathodes to investigate the effect of the ion and electron transport on the electrochemical properties, including the effective transport properties, MacMullin number, and the tortuosity factor. The obtained results in turn confirm the findings from the in situ TEM. These findings are applicable to optimize other S‐based active materials and improve their utilization.

Room Temperature Halide‐Eutectic Solid Electrolytes with Viscous Feature and Ultrahigh Ionic Conductivity

“…The ionic and electronic conductivity of the LFP‐additive mixtures were measured on symmetric cells to evaluate the different conducting effects of the LPSCl and AG55 additives. Considering Li–In is a mixed conductor, to strictly block the electron conduction, two LPSCl solid electrolyte pellets were used as ion conduction and electron insulation layers in the symmetric cells to study the ionic conductivity, [ 41 ] as shown in Figure 5g,h . Li–In foils were used as electrodes to maintain a stable LPSCl/Li‐In interface.…”

“…The SEM and TEM samples were transferred in an Ar‐protected holder. [ 41b ] TEM was measured at a cryogenic temperature of −170 °C.…”

Facilely Fabricating V2O3@C Nanosheets Grown on rGO as High-Performance Negative Materials for Lithium-Ion Batteries by Adjusting Surface Tension

“…The charge transfer resistance R ct values of the V 2 O 3 @C/rGO and V 2 O 3 @C electrodes are 23 Ω and 98 Ω, and their SEI film resistance R sf values are 4 Ω and 45 Ω, respectively. The smaller R ct and R sf values of the V 2 O 3 @C/rGO electrode are more beneficial to electron and lithium ion transfer during the cyclic process. − This result proves that the fast electron and lithium ion transfer rate of the V 2 O 3 @C/rGO electrode is the reason for its large reversible capacity and superior rate capability. The smaller R ct (19 Ω) after 100 cycles than the value of the V 2 O 3 @C/rGO electrode after five cycles (Figure S10) indicates superior conductivity and faster Li + diffusion, which are in agreement with the increase in capacity.…”

Failure analysis of the Ge-substituted Li6PS5I with bare LiNi0.8Co0.1Mn0.1O2 and performance improvement via Li2ZrO3 coating

“…23 Therein, the sulfide-based SE with high ionic conductivity (over 10 −4 S cm −1 ) and small grain boundary resistance at room temperature is an ideal option to realize high rate and high active material loading SSBs. 24–28 Particularly, the ionic conductivity of reported sulfides can surpass 10 −2 S cm −1 at room temperature, such as Li 10 GeP 2 S 12 , Li 6.6 Sb 0.4 Si 0.6 S 5 I, and Li 6.5 Sb 0.5 Ge 0.5 S 5 I, which are even higher than the typical liquid electrolytes. 29–31 The ultrahigh ionic conductivity can meet the ionic percolation demand and make full use of active materials even at lower temperatures.…”