Abstract:Recently, several sulfide solid electrolytes have been synthesized
by liquid-phase synthesis for the commercialization of all-solid-state
batteries. Unfortunately, the ionic conductivity for most of these
electrolytes is unsatisfactory compared to that of solid electrolytes
synthesized by conventional ball milling. This problem is attributed
to different mechanisms between the liquid phase and the solid phase
in reaction and formation. However, to the best of our knowledge,
the effect of the solvent on the ion… Show more
“…The precursor powders in ACN and THP both exhibited three steps of weight loss. Several studies have demonstrated that forward DTA scans of Li 3 PS 4 complexes containing organic solvent exhibit large endothermic peaks 13 , 14 . Further, the decomposition reaction of Li 7 P 3 S 11 to Li 4 P 2 S 6 , Li 3 PS 4 , and sulfur occurs at a temperature higher than 280°C 30 , 31 .…”
Section: Resultsmentioning
confidence: 99%
“…In addition to the dielectric constant, the donor number may also play a role in reactivity. Figure 5 ( a ) Nyquist plot and ( b ) ionic conductivity at room temperature for 70Li 2 S–30P 2 S 5 system formed via Dox, THP, and ACN solvents as a function of dielectric constant together with those of 70Li 2 S–30P 2 S 5 system formed via other solvents 12 – 14 . The white circles indicate reference values.…”
Section: Resultsmentioning
confidence: 99%
“…However, the high reactivity of the Li 2 S–P 2 S 5 system in low-DN ACN solvent cannot be explained by the DN. In the case of Li 3 PS 4 synthesized via a solvent, the use of a solvent with low polarity will lead to higher ionic conductivity since solvents with low polarity are more easily removed and yield a lower crystallinity ratio 14 , 38 . In contrast, the intrinsic high ionic conductivity of Li 7 P 3 S 11 is caused by a high level of crystallinity 32 , which is explained by the presence of P 2 S 7 polyhedra in the Li 7 P 3 S 11 structure 39 .…”
Section: Resultsmentioning
confidence: 99%
“…Liu et al have reported that a wet chemical method based on tetrahydrofuran (THF) solvent is effective for the preparation of β -Li 3 PS 4 , a typical sulfide electrolyte 13 . In addition, Li 2 S–P 2 S 5 solid electrolytes have been synthesized in organic solvents, such as propionate (EP), butyl acetate (BA) 14 , and acetonitrile (ACN). Recently, Yamamoto et al demonstrated the effect of solvent on the ionic conductivity of Li 3 PS 4 synthesized using a liquid-phase process 14 .…”
Section: Introductionmentioning
confidence: 99%
“…In addition, Li 2 S–P 2 S 5 solid electrolytes have been synthesized in organic solvents, such as propionate (EP), butyl acetate (BA) 14 , and acetonitrile (ACN). Recently, Yamamoto et al demonstrated the effect of solvent on the ionic conductivity of Li 3 PS 4 synthesized using a liquid-phase process 14 . The ionic conductivity of Li 3 PS 4 prepared from a liquid phase was found to have a strong correlation with the polarity, , of the solvent, reaching 5.09 × 10 –4 S cm –1 at room temperature when using BA with a low polarity.…”
Synthesis technology for sulfide-based solid electrolytes based on liquid-phase processing has attracted significant interest in relation to achieving the optimal design for all-solid-state batteries. Herein, guidelines to solvent selection for the liquid-phase synthesis of superionic conductor Li7P3S11 are described through systematic examination. 70Li2S–30P2S5 system, a source of Li7P3S11, is treated via a wet chemical reaction using eight organic solvents with different physical and chemical properties (i.e., dielectric constant, molecule structure, and boiling point). We reveal that the solvent’s polarity, characterized by the dielectric constant, plays an important role in the formation of crystalline Li7P3S11 via wet chemical reaction. In addition, acetonitrile (ACN) solvent with a high dielectric constant was found to lead to high-purity crystalline Li7P3S11 and intrinsically high ionic conductivity. Further, solvents with a high boiling point and ring structures that cause steric hindrance were found to be unfavorable for the wet chemical synthesis of Li7P3S11 solid electrolyte. Overall, we demonstrate that ACN solvent is the most suitable for the liquid-phase synthesis of a crystalline Li7P3S11 solid electrolyte with high purity based on its dielectric constant, molecular structure, and boiling point.
“…The precursor powders in ACN and THP both exhibited three steps of weight loss. Several studies have demonstrated that forward DTA scans of Li 3 PS 4 complexes containing organic solvent exhibit large endothermic peaks 13 , 14 . Further, the decomposition reaction of Li 7 P 3 S 11 to Li 4 P 2 S 6 , Li 3 PS 4 , and sulfur occurs at a temperature higher than 280°C 30 , 31 .…”
Section: Resultsmentioning
confidence: 99%
“…In addition to the dielectric constant, the donor number may also play a role in reactivity. Figure 5 ( a ) Nyquist plot and ( b ) ionic conductivity at room temperature for 70Li 2 S–30P 2 S 5 system formed via Dox, THP, and ACN solvents as a function of dielectric constant together with those of 70Li 2 S–30P 2 S 5 system formed via other solvents 12 – 14 . The white circles indicate reference values.…”
Section: Resultsmentioning
confidence: 99%
“…However, the high reactivity of the Li 2 S–P 2 S 5 system in low-DN ACN solvent cannot be explained by the DN. In the case of Li 3 PS 4 synthesized via a solvent, the use of a solvent with low polarity will lead to higher ionic conductivity since solvents with low polarity are more easily removed and yield a lower crystallinity ratio 14 , 38 . In contrast, the intrinsic high ionic conductivity of Li 7 P 3 S 11 is caused by a high level of crystallinity 32 , which is explained by the presence of P 2 S 7 polyhedra in the Li 7 P 3 S 11 structure 39 .…”
Section: Resultsmentioning
confidence: 99%
“…Liu et al have reported that a wet chemical method based on tetrahydrofuran (THF) solvent is effective for the preparation of β -Li 3 PS 4 , a typical sulfide electrolyte 13 . In addition, Li 2 S–P 2 S 5 solid electrolytes have been synthesized in organic solvents, such as propionate (EP), butyl acetate (BA) 14 , and acetonitrile (ACN). Recently, Yamamoto et al demonstrated the effect of solvent on the ionic conductivity of Li 3 PS 4 synthesized using a liquid-phase process 14 .…”
Section: Introductionmentioning
confidence: 99%
“…In addition, Li 2 S–P 2 S 5 solid electrolytes have been synthesized in organic solvents, such as propionate (EP), butyl acetate (BA) 14 , and acetonitrile (ACN). Recently, Yamamoto et al demonstrated the effect of solvent on the ionic conductivity of Li 3 PS 4 synthesized using a liquid-phase process 14 . The ionic conductivity of Li 3 PS 4 prepared from a liquid phase was found to have a strong correlation with the polarity, , of the solvent, reaching 5.09 × 10 –4 S cm –1 at room temperature when using BA with a low polarity.…”
Synthesis technology for sulfide-based solid electrolytes based on liquid-phase processing has attracted significant interest in relation to achieving the optimal design for all-solid-state batteries. Herein, guidelines to solvent selection for the liquid-phase synthesis of superionic conductor Li7P3S11 are described through systematic examination. 70Li2S–30P2S5 system, a source of Li7P3S11, is treated via a wet chemical reaction using eight organic solvents with different physical and chemical properties (i.e., dielectric constant, molecule structure, and boiling point). We reveal that the solvent’s polarity, characterized by the dielectric constant, plays an important role in the formation of crystalline Li7P3S11 via wet chemical reaction. In addition, acetonitrile (ACN) solvent with a high dielectric constant was found to lead to high-purity crystalline Li7P3S11 and intrinsically high ionic conductivity. Further, solvents with a high boiling point and ring structures that cause steric hindrance were found to be unfavorable for the wet chemical synthesis of Li7P3S11 solid electrolyte. Overall, we demonstrate that ACN solvent is the most suitable for the liquid-phase synthesis of a crystalline Li7P3S11 solid electrolyte with high purity based on its dielectric constant, molecular structure, and boiling point.
Alkali (lithium, sodium)‐based second batteries are considered one of the brightest candidates for energy‐storage applications in order to utilize the random and intermittent renewable energy to achieve carbon neutrality. Conventional lithium/sodium batteries containing liquid organic electrolytes are vulnerable to electrolytes leakage and even combustion, which hinders their large‐scale and reliable application. All‐solid‐state electrolytes which are considered to have better safety have been developed in recent years. However, most of them suffer from low ionic conductivity and large interfacial resistance with the electrode. Ionogel‐electrolyte membranes composed of ionic liquids and solid matrices, have attracted much attention because of their nonvolatility, nonflammability, and superior chemical and electrochemical properties. This review focuses on the most recent advances of ionogel electrolytes that sprang up with the emerging demand and progress of safe lithium/sodium batteries. The ionogel‐electrolyte membranes are discussed based on the framework components and preparation methods. Their structure and properties, including ionic conductivity, mechanical strength, electrochemical stabilities, and so on, are demonstrated in combination with their applications. The current challenges and insights on the future development of ionogel electrolytes for advanced safe lithium/sodium batteries are also proposed.
SSEs based on sulfides, [2] oxides, [3] halides, [4] and borohydrides [5] have been developed over the past decades, including those demonstrating high ionic conductivity (e.g., 12 mS cm −1 for Li 10 GeP 2 S 12 , LGPS, and 25 mS cm −1 for Li 9.54 Si 1.74 P 1.44 S 11.7 Cl l0.3 , LSPSCl), [2] highvoltage stability (e.g., 4.21 V versus Li + / Li for Li 3 YCl 6 , LYC, and 4.3 V versus Li + / Li for Li 3 InCl 6 , LIC), [6] low cost (Li 2 ZrCl 6 and Li 2.25 Zr 0.75 Fe 0.25 Cl 6 ), [7] and appropriate mechanical properties. [8] With these advances in SSEs, various cathode materials have been attempted in ASSBs, such as LiCoO 2 (LCO), [9] LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532), [10] and Ni-rich layered cathode materials (e.g., LiNi 0.8 Mn 0.1 Co 0.1 O 2 , NMC811, [4c] LiNi 0.85 Co 0.1 Mn 0.05 O 2 ,Ni85, [11] and LiNi 0.90 Co 0.05 Mn 0.05 O 2 , Ni90 [12] ). These cathode materials typically show a specific capacity of <200 mAh g −1 , [13] which limits the energy density of ASSBs to less than 450 Wh kg −1 . [14] Comparatively, lithium-rich layered oxide (LLO) possesses a higher theoretical capacity of ≥250 mAh g −1 , [15] and is thus a promising candidate for achieving ASSBs with an energy density of 500 Wh kg −1 Employing lithium-rich layered oxide (LLO) as the cathode of all-solid-state batteries (ASSBs) is highly desired for realizing high energy density. However, the poor kinetics of LLO, caused by its low electronic conductivity and significant oxygen-redox-induced structural degradation, has impeded its application in ASSBs. Here, the charge transfer kinetics of LLO is enhanced by constructing high-efficiency electron transport networks within solidstate electrodes, which considerably minimizes electron transfer resistance. In addition, an infusion-plus-coating strategy is introduced to stabilize the lattice oxygen of LLO, successfully suppressing the interfacial oxidation of solid electrolyte (Li 3 InCl 6 ) and structural degradation of LLO. As a result, LLO-based ASSBs exhibit a high discharge capacity of 230.7 mAh g −1 at 0.1 C and ultra-long cycle stability over 400 cycles. This work provides an in-depth understanding of the kinetics of LLO in solid-state electrodes, and affords a practically feasible strategy to obtain high-energy-density ASSBs.
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