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In order to use sulfide all-solid-state batteries as power sources of electric devices, sulfide solid electrolytes with high ionic conductivity and high air-stability must be developed. Li3PS4 electrolytes have been used in all-solid-state batteries because of their relatively high ionic conductivity (4 × 10 −4 S cm−1 at 25 °C) and higher air-stability than those of other Li2S–P2S5 type solid electrolytes. Herein, the Li4SnS4–Li3PS4 system was investigated to (1) increase the ionic conductivity of Li3PS4 using excess Li carriers and (2) improve the air-stability of Li3PS4 by introducing air-stable Sn–S bonds. The structure, ionic conductivity, and air-stability of xLi4SnS4·(1−x)Li3PS4 were systematically investigated; the results showed that adding small amounts of Li4SnS4 to Li3PS4 glass and glass-ceramic enhanced their ionic conductivity and air-stability without degrading their electrochemical stability. In particular, the 0.3Li4SnS4·0.7Li3PS4 glass-ceramic showed an ionic conductivity of 8.1 × 10 −4 S cm−1 at 25 °C and generated only a small amount of H2S gas (3 ppm [0.3 cm3 g−1]) when it was dissolved in water. Hence, xLi4SnS4·(1−x)Li3PS4 solid electrolytes can be used as alternatives to the conventional Li3PS4 electrolyte because of their various advantages and a simple preparation method that involves adding only SnS2 to conventional starting materials.

Studies on local conduction paths in composite electrodes are essential to the realization of high-performance sulfide all-solid-state lithium batteries. Here, we directly evaluate the electrical p...

The application of lithium metal as a negative electrode in all-solid-state batteries shows promise for optimizing battery safety and energy density. However, further development relies on a detailed understanding of the chemo-mechanical issues at the interface between the lithium metal and solid electrolyte (SE). In this study, crack formation inside the sulfide SE (Li

Addition of LiI and Li3PS4 to hexagonal Li4SnS4 enhances ionic conductivity without decreasing the air stability of Li4SnS4.

The dynamic changes of ionic conduction path in the cross-sectional graphite composite electrodes of bulk-type all-solid-state lithium batteries have been monitored using operando confocal microscopic observations for color changes of graphite in response to their stage structures. The ionic conduction path decreased in the cross-sectional direction as cycle numbers increased, with simultaneous capacity degradation. The local reactivity of lithiation and delithiation was evaluated by image analysis considering state-of-charge (SOC) values. Electrode thickness changes were examined from the confocal microscope images obtained in the operando observations. The results revealed that voids and cracks were formed during cycle tests and that the thickness gradually increased. These cracks and voids were one of the main contributors to the limitation of ionic conduction paths in the depth direction. Operando microscopic observation and subsequent image analysis elucidated not only the morphological changes of active materials but also the differences in local SOC changes in the electrode.

The reaction uniformity of LiCoO2 composite positive electrodes in all-solid-state cells was compared quantitatively by investigating the Raman band shifts corresponding to the state-of-charge (SOC) of LiCoO2. The quantitative SOC analysis was conducted using the Raman imaging data of composite electrodes with smaller or larger solid electrolytes. The electrodes exhibited different reaction uniformity although the cells showed similar initial charge capacities and average SOC. In the case of larger solid electrolytes, most LiCoO2 particles showed higher or lower SOC than the average SOC, and lower battery performance. The quantitative analysis of SOC in each LiCoO2 electrode demonstrated that a variable SOC outside the average SOC resulted in larger irreversible capacity and lower rate performance. The quantitative SOC analysis newly developed in the present study is a useful technique for designing composite electrodes showing higher battery performance.

Studies on local conduction paths in composite electrodes are essential to the realization of high-performance sulfide all-solid-state lithium batteries. Here, we directly evaluate the electrical properties of individual LiNi1/3Mn1/3Co1/3O2 (NMC) electrode active material particles in composite positive electrodes by scanning probe microscopy (SPM) techniques. Kelvin probe force microscopy (KPFM) and scanning spreading resistance microscopy (SSRM) were combined. The results indicated that all NMC particles exhibit a charged state with increasing potential, but low electronic conduction paths exist at point contacts of some NMC particles. Furthermore, the I-V characteristics measured by conductive-atomic force microscopy (C-AFM) suggest that these specific NMC particles show low charge-discharge reactivity. The results of the SPM techniques indicate that poor conduction locally limits the charge-discharge reactivity of electrode active materials, leading to the degradation of battery performance. Such SPM combination accelerates the morphological optimization of composite electrodes by facilitating the investigation of the intrinsic electrical properties of the electrodes.

Long-lasting all-solid-state batteries can be achieved by preventing side reactions in the composite electrodes comprising electrode active materials and solid electrolytes. Typically, the battery performance can be enhanced through the use of robust solid electrolytes that are resistant to oxidation and decomposition. In this study, the thermal stability of sulfide solid electrolytes Li3PS4 and Li4SnS4 toward oxide positive electrode active materials was estimated by investigating the occurrence of side reactions at the electrolyte-electrode interfaces when the composite electrodes are heated in an accelerated aging test: Li4SnS4 showed higher thermal stability because of the suppression of the substitution reaction between S and O. Moreover, thermally stable sulfide solid electrolytes are amenable to an improved cell construction process. The sintering (pelletizing and subsequent heating) of the composite electrodes with Li4SnS4 as the solid electrolyte allowed the manufacture of dense electrodes that exhibited increased ionic conductivity, thereby enhancing the battery performance.

Composite graphite negative electrodes were prepared by mixing graphite particles and 75Li2S·25P2S5 (mol%) glass particles with weight ratios of x:100 − x (x = 50, 60 and 70). The cell with the x = 50 electrode showed the highest reversible capacity of more than 250 mAh g−1. Optical microscopy was conducted for each composite electrode after electrochemical lithiation to investigate reaction distributions by color changes of graphite particles. In the x = 50 electrodes, almost all the graphite particles changed to gold color, suggesting that the graphite particles were fully lithiated. In situ optical microscopy was also carried out for the composite graphite electrode to monitor color changes of graphite particles directly during charge-discharge tests.

A new crystalline lithium-ion conducting material, Li4SnS4 with an ortho-composition, was prepared by a mechanochemical technique and subsequent heat treatment. Synchrotron X-ray powder diffraction was used to analyze the crystal structure, revealing a space group of P63/ mmc and cell parameters of a = 4.01254(4) A and c = 6.39076(8) A. Analysis of a heat-treated hexagonal Li4SnS4 sample revealed that both lithium and tin occupied either of two adjacent tetrahedral sites, resulting in fractional occupation of the tetrahedral site (Li, 0.375; Sn, 0.125). The heat-treated hexagonal Li4SnS4 had an ionic conductivity of 1.1 × 10-4 S cm-1 at room temperature and a conduction activation energy of 32 kJ mol-1. Moreover, the heat-treated Li4SnS4 exhibited a higher chemical stability in air than the Li3PS4 glass-ceramic.

Sulfide-based all-solid-state lithium batteries are a next-generation power source composed of the inorganic solid electrolytes which are incombustible and have high ionic conductivity. Positive electrode composites comprising LiNi1/3Mn1/3Co1/3O2 (NMC) and 75Li2S·25P2S5 (LPS) glass electrolytes exhibit excellent charge–discharge cycle performance and are promising candidates for realizing all-solid-state batteries. The thermal stabilities of NMC–LPS composites have been investigated by transmission electron microscopy (TEM), which indicated that an exothermal reaction could be attributed to the crystallization of the LPS glass. To further understand the origin of the exothermic reaction, in this study, the precipitated crystalline phase of LPS glass in the NMC–LPS composite was examined. In situ TEM observations revealed that the β-Li3PS4 precipitated at approximately 200 °C, and then Li4P2S6 and Li2S precipitated at approximately 400 °C. Because the Li4P2S6 and Li2S crystalline phases do not precipitate in the single LPS glass, the interfacial contact between LPS and NMC has a significant influence on both the LPS crystallization behavior and the exothermal reaction in the NMC–LPS composites.

Amorphous transition metal polysulfides are promising high capacity electrode active materials for sodium secondary batteries. Here we report the superior electrode performance of amorphous Na2TiS3...

Sulfide-based all-solid-state batteries using a non-flammable inorganic solid electrolyte are promising candidates as a next-generation power source owing to their safety and excellent charge–discharge cycle characteristics. In this study, we thus focus on the positive electrode and investigated structural stabilities of the interface between the positive electrode active material LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC) and the 75Li 2 S·25P 2 S 5 (LPS) glass electrolyte after charge–discharge cycles via transmission electron microscopy (TEM). To evaluate the thermal stability of the fabricated all-solid-state cell, in-situ TEM observations for the positive electrode during heating are conducted. As a result, structural and morphological changes are detected in the LPS glasses. Thus, exothermal reaction present in the NMC-LPS composite positive electrode after the initial charging is attributable to the crystallization of LPS glasses. On the basis of a comparison with crystallization behavior in single LPS glasses, the origin of exothermal reaction in the NMC-LPS composites is discussed.

Bulk-type all-solid-state batteries, which use composite electrodes with a powder mixture of active materials and solid electrolytes, are anticipated for large-scale power sources. However, conventional powder mixing protocols are insufficient to maintain ion-conductive pathways within composite electrodes. Herein, sulfide electrolyte coatings have attracted attention as a promising means to overcome this difficulty. We assessed the effects of sulfide electrolyte coatings for active materials on the electrochemical properties and structural changes in all-solid-state cells. A favorable electrode-electrolyte interface was formed by coating significantly small amounts (ca. 3 wt%) of Li4GeS4-Li3PS4 solid electrolyte (SE) onto LiCoO2 particles via vapor phase process. The all-solid-state cell (In/Li2S-P2S5/SE-coated LiCoO2) was charged and discharged with a larger capacity than that using non-SE-coated LiCoO2 particles, indicating that the SE-coating is effective in forming a favorable ion-conductive pathway to LiCoO2 particles. Improvement of the cell performance after heat treatment was considered to derive not only from the enhancement of ionic conductivity in the SE-coating layer, but also from the reduction of voids in the composite electrode. Less ionic resistance and denser environment are beneficial for the Li-ion supply to the deepest part in the composite electrode, which results in more homogeneous electrochemical reaction in all-solid-state cells.

A positive electrode containing Li3PS4 (LPS) glasses and LiNi1/3Mn1/3Co1/3O2 (NMC) is a promising candidate for sulfide-based all-solid-state lithium batteries owing to its excellent charge–discharge cycle characteristics. However, sulfide-based solid electrolytes exhibit low chemical stability in air. This disadvantage affects process cost and thermal stability of all-solid-state cells. To resolve these issues, in this study, we focus on solid electrolytes, Li4SnS4 (LSS), that do not generate H2S gas in air. The thermal behavior and microstructure of LSS–NMC positive electrode composites before and after the initial charge–discharge cycle are investigated. The initially charged LSS–NMC composites exhibit several exothermal reactions above 250 °C. However, pristine and initially discharged samples do not show any considerable exothermal reactions. For LPS–NMC composites, by contrast, exothermal reactions are detected regardless of the charging and discharging state. To clarify the exothermic factors of initially charged LSS–NMC composites, we performed ex situ transmission electron microscopy observation and X-ray diffraction measurements. It is determined that SnS2, transition metal sulfides, and metal oxides are formed above 300 °C, which is attributable to LSS and NMC decomposition reactions. On the basis of the relation between thermal behavior and corresponding structural changes, exothermic factors and thermal stability of LSS–NMC composites are discussed in comparison with LPS–NMC composites.

A new crystalline lithium-ion conducting material, Li

A composite positive electrode in an all-solid-state battery is prepared by mixing LiCoO2 particles and Li2S–P2S5 solid electrolytes. Raman spectroscopy is conducted for the composite positive electrodes before and after the initial charging process. Raman spectral changes are observed, which corresponds to structural changes of LiCoO2 particles during the charge test. However, some spectra indicate that several LiCoO2 particles show no structural changes although the cell is fully charged. A local state-of-charge (SOC) distribution map of the composite electrode is obtained by Raman mapping. The mapping image after the charge test shows that distributions of reactions exist in the composite positive electrode.

Sulfide-based all-solid-state lithium batteries are expected to be a next-generation power source because of their high energy density, good charge–discharge characteristics, and incombustibility. A positive electrode composite comprising LiNi1/3Mn1/3Co1/3O2 (NMC) and Li3PS4 (LPS) glass electrolyte shows excellent charge–discharge cycle characteristics. To understand exothermal reactions during the heating process of this battery material, structural and morphological changes were investigated mainly by ex situ X-ray diffraction measurements as well as ex situ transmission and scanning electron microscopy observations. We found that a number of transition-metal sulfides, such as MnS and CoNi2S4, and Li3PO4 nanocrystallites were formed in a sample heated at a temperature above the exothermic peak temperature. In addition, no substantial difference was observed in the behavior of these structural and morphological changes due to charge and discharge cycles. The formation of transition-metal sulfides and Li3PO4 crystalline phases suggests that, when exposed to real cell operating environments, LPS and NMC undergo a chemical reaction via heat treatment, which directly leads to the exothermal reactions.

Recently, all-solid-state lithium batteries have attracted global attentions as next-generation batteries because of their higher safety due to the use of nonflammable inorganic solid electrolytes instead of flammable organic liquid electrolytes. Bulk-type all-solid-state batteries employ composite electrodes consisting of electrode active materials and solid electrolytes. There are a lot of solid-solid interfaces in composite electrode layers resulting in inhomogeneous reaction distributions. In order to achieve higher battery performance, it is important to investigate electrochemical reaction mechanisms at the solid-solid interfaces and evaluate reaction distributions in the electrode layers. A graphite negative electrode is used in commercial lithium-ion batteries. However, there are few papers regarding all-solid-state batteries using graphite composite electrodes.[1] It is worth studying reaction mechanisms of graphite composite electrodes in all-solid-state lithium batteries for practical use in the near future. Colors of graphite particles change from black via dark blue and red to gold during a lithiation process.[2] Observation of color changes enables us to evaluate reaction distributions in a graphite electrode layer. In our previous paper, we compared reaction distributions of composite negative electrodes consisted of graphite and sulfide solid electrolytes with weight ratios of x : 100-x (x = 50, 60 and 70) by ex-situ optical microscopy.[3] The cell using the x = 50 electrode showed the highest reversible capacity of more than 250 mAh g-1 and homogeneous reaction distributions. In this study, to monitor forming of reaction distributions during charge-discharge cycles, operando optical microscopy was conducted for a graphite electrode layer in an all-solid-state cell. Composite electrodes were prepared by mixing graphite and 75Li2S·25P2S5 (mol%) glass electrolyte particles with weight ratios of 50 : 50. 75Li2S·25P2S5 glass and lithium-indium alloy were used as a solid electrolyte separator and a counter electrode, respectively. The cell (Li-In/75Li2S·25P2S5 glass/Graphite) was cut to obtain flat cross-sectional observation areas. Operando optical microscopic observation was conducted for the cross-section of the graphite electrode layer at room temperature under a current density of 0.068 mA cm-2. The cell was mounted under a low confined pressure of ca. 70 kPa in an Ar-filled vessel during optical microscopy. Optical micrographs for the graphite electrode layer showed that lithiation and delithiation proceeded preferentially for the graphite particles near the solid electrolyte layer. The color changes in the graphite particles were quantitatively evaluated to compare SOC values. During the initial lithiation process, almost all the graphite particles in the electrode layer changed their colors from black to gold. However, after the 3rd lithiation process, only the graphite particles near the electrolyte separator layer showed color changes. The SOC value for the graphite near the separator layer side was more than twice as high as that near the current collector side. This suggested that inhomogeneous reaction distributions were formed in the graphite electrode layer, which resulted in degradation of cycle performances. In addition, the thickness changes of the graphite electrode layer during charge-discharge tests were also examined. Acknowledgement: Optical microscopic observation was supported by Lasertec Corp.. Reference s: [1] K. Takada, T. Inada, A. Kajiyama, H. Sasaki, S. Kondo, M. Watanabe, and R. Kanno, Solid State Ionics, 158 (2003) 269–274. [2] S. J. Harris, A. Timmons, D. R. Baker, and C. Monroe, Chem. Phys. Lett., 485 (2010) 265–274. [3] M. Otoyama, A. Sakuda, A. Hayashi, and M. Tatsumisago, Solid State Ionics, 323 (2018) 123-129.

All-solid-state batteries show higher safety with low risk of leakage and explosion because of nonflammable inorganic solid electrolytes, which are alternative to conventional organic liquid electrolytes. Bulk-type all-solid-state batteries are constructed by pressing positive and negative electrode layers and a solid electrolyte layer at room temperature. The batteries are capable of having high energy density by adding large amounts of active materials into composite electrodes, which are composed of solid electrolyte particles and active material particles. We have investigated electrochemical performances of bulk-type all-solid-state cells using a LiCoO2 composite positive electrode and a Li2S-P2S5 solid electrolyte.1 Composite positive electrodes have many solid-solid interfaces, and electrochemical reactions at the interfaces have not been studied well. Inhomogeneous reaction may occur in the composite electrodes when solid-solid contact areas are insufficient. To improve cell performance, investigation of state-of-charge (SOC) distributions in the electrodes and fabrication of electrodes showing uniform reaction distributions are important. Raman spectroscopy is a suitable technique for investigating SOC of active materials because Raman spectra are sensitive to the structural changes of active materials during charge-discharge tests. Moreover, Raman mapping technique enables us to obtain SOC distribution maps of composite electrodes. In this study, Raman mapping was carried out for charged and discharged LiCoO2 composite positive electrodes in all-solid-state cells to investigate SOC distributions. A 75Li2S·25P2S5 (mol%) glass and indium foil were used as a solid electrolyte and a negative electrode, respectively. A composite positive electrode was prepared by mixing LiCoO2 particles and 75Li2S·25P2S5 glass particles with 80:20 in weight ratio. All-solid-state cells were charged and discharged with a cut-off voltage of 2.6-4.2 V (vs. Li+/Li) at 25oC under a current density of 0.064 mA cm-2. Raman mapping was conducted for surface parts of composite positive electrodes prepared by an Ar ion-milling technique. There are two strong Raman bands at 486 and 596 cm-1, originating from the E g and A 1g modes corresponding to O-Co-O bending and Co-O stretching, respectively.2 Those peaks of E g and A 1g modes shifted to 470 cm-1 and 582 cm-1 respectively, when the cell was charged to 4.2 V (vs. Li+/Li) and returned to original peak positions after the discharging process. To evaluate SOC of the composite positive electrode, A 1g peak positions were investigated in detail. The mapping image showed that charge-discharge reactions did not proceed uniformly, and inhomogeneous reaction distributions existed at the areas of insufficient contacts between LiCoO2 particles and solid electrolyte particles.3 To achieve uniform electrochemical reactions, a composite positive electrode having sufficient interfaces between LiCoO2 and solid electrolyte particles should be prepared. To increase contact points between them, a composite positive electrode with solid electrolytes with a smaller particle size was fabricated. Raman mapping images of the charged and discharged electrodes suggest that uniform electrochemical reactions are achieved. It is noteworthy that the use of smaller solid electrolyte particles is effective way to obtain uniform reaction distributions for composite positive electrodes in all-solid-state lithium batteries. Acknowledgement This research was financially supported by JST, ALCA-SPRING. References [1] T. Minami et al., Solid State Ionics, 177 (2006) 2715-2720. [2] M. Inaba et al., J. Raman Spectrosc., 28 (1997) 613-617. [3] M. Otoyama et al., J. Power Sources, 302 (2016) 419-425.

All-solid-state batteries with nonflammable inorganic solid electrolytes, an alternative to conventional inflammable organic liquid electrolytes, are widely studied as next generation batteries with low risk of leakage and explosion. Bulk-type batteries use composite electrodes of active materials and solid electrolytes. Solid electrolytes play a role of delivering Li ions to active materials. Bulk-type batteries are capable of having high energy density by adding large amounts of active materials into composite electrodes. We have investigated the electrochemical performance of bulk-type all-solid-state cells using a LiCoO2 composite positive electrode and a Li2S-P2S5 solid electrolyte [1]. Composite electrodes can be fabricated by mixing LiCoO2 particles and solid electrolyte particles. There are many solid-solid interfaces in composite electrodes. It is important that electrochemical reactions at LiCoO2-electrolyte solid-solid interfaces are clarified to improve the cell performance. Raman microscopy is one of the useful methods for investigating the reactions because of its feature of high spatial resolution and surface sensitivity. Raman spectral changes of composite electrodes are closely related to the structural changes of active material during charge-discharge cycling. In this study, Raman spectroscopy was carried out for LiCoO2 composite positive electrodes in all-solid-state cells before and after the charge-discharge process. Moreover, Raman mapping was conducted to evaluate state-of-charge (SOC) distributions of each active material in the electrodes. The 75Li2S·25P2S5 (mol%) glass and indium foil were used as solid electrolyte and a negative electrode, respectively. A composite positive electrode was prepared by mixing LiCoO2 particles and 75Li2S·25P2S5 glass particles (80:20 wt.%). All-solid-state cells were charged and discharged with a cut-off voltage of 2.6-4.2 V (vs. Li+/Li) at 25 oC under a current density of 0.064 mA cm-2. Raman spectra were obtained for the surface part of composite positive electrodes prepared by an Ar ion-milling technique. There are two strong Raman peaks at 486 and 596 cm-1, originating from the E g and A 1g modes of oxygen vibration in LiCoO2, respectively. Those peaks shifted to the lower wavenumber side and their intensity decreased after the initial charging process. After the discharging process, those peaks returned to the original positions. Mapping images showed charge-discharge reactions did not proceed uniformly at the areas of insufficient contacts between LiCoO2 particles and solid electrolyte particles [2]. Our approaches to fabricate composite positive electrodes having uniform charge-discharge reactions will be demonstrated. Acknowledgement This research was financially supported by JST, ALCA-SPRING. References [1] T. Minami et al., Solid State Ionics, 177 (2006) 2715-2720. [2] M. Otoyama et al., J. Power Sources, 302 (2016) 419-425.

As next generation batteries, all-solid-state batteries using inorganic solid electrolytes are widely investigated. Bulk-type batteries, which use composite electrodes of active material and electrolyte powders, are anticipated for power sources with high energy density. Solid electrolyte thin films are useful for the formation of an ideal electrode-electrolyte interface in bulk-type batteries. Furthermore, the solid electrolyte contents in composite electrodes can be reduced significantly. We previously reported the preparation of amorphous Li2S-P2S5 and Li2S-GeS2 thin films by pulsed laser deposition (PLD), and this technique was applied for solid electrolyte coatings on LiCoO2 particles. In order to further improve the battery performance, solid electrolyte thin films with higher lithium-ion conductivity are demanded. We fabricated the Li2S-GeS2-P2S5 thin film with an ionic conductivity of 1.1×10-4 S cm-1, and the conductivity was increased to 1.8×10-3 S cm-1 by a heat treatment at 200 oC. In this study, bulk-type all-solid-state batteries using LiCoO2 particles coated with Li2S-GeS2-P2S5thin films were constructed. For the fabricated batteries, we investigated charge-discharge performances, electrode-electrolyte interfacial resistances, and microstructural changes in the composite electrode. Moreover, Raman mapping was conducted for the composite electrode to investigate the local SOC distributions. The surface of LiCoO2 particles was uniformly covered with Li2S-GeS2-P2S5 (SE) thin films. The thickness of SE-coating layer was estimated to be about 180 nm, corresponding to the amount of 3 wt% SE in the composite electrode. In SEM images of positive electrode using LiCoO2 particles with SE-coatings, SE-coating layer was in close contact with LiCoO2 particles. However, a lot of voids were observed in the electrode layer. On the other hand, the number of voids in the positive electrode decreased considerably in SEM images of positive electrode using SE-coated LiCoO2 particles with heat treatment at 200 oC. The all-solid-state cell using SE-coated LiCoO2 particles was charged and discharged with a larger capacity than that using non SE-coated LiCoO2 particles. Moreover, the all-solid-state battery using SE-coated LiCoO2 with heat treatment showed a larger capacity and better cycle performance. At the impedance plots after charging process, the interfacial resistance between positive electrode and SE-coating layer decreased to 5.8 Ω cm2 after heat treatment. The cell using SE-coated LiCoO2 particles with heat treatment was discharged under high current density of more than 3.9 mA cm-2 at room temperature. Raman mapping image for composite electrode using LiCoO2particles with SE-coating and subsequent heat treatment indicated that electrochemical reactions did proceed more uniformly. Sulfide electrolyte coatings on active material are considered to be effective in forming an ideal electrode-electrolyte interface, resulting in the increase of energy density in bulk-type all-solid-state batteries. Furthermore, the effect of heat treatment for SE-coated LiCoO2particles is considered to be the increase of ionic conductivity in SE-coating layer, and the decrease of voids in the composite electrode. Especially, the decrease of voids is effective in the reduction of the loss of lithium-ion conduction paths. These effects of SE-coating and heat treatment would lead to a larger discharge capacity, better cycle performance, and better rate performance in the fabricated all-solid-state cells.