Patent Description:
Powder-dispersed positive electrodes are widely known as layers of positive electrode active material for secondary lithium batteries (also referred to as secondary lithium ion batteries), and are usually produced by kneading and molding particles of lithium complex oxide (typically, lithium-transition metal oxide) and additives, such as binders or conductive agents. Such powder-dispersed positive electrodes contain a relatively large amount (e.g., about <NUM>% by weight) of binder that does not contribute to the capacity of battery, resulting in a low packing density of the positive electrode active material, i.e., lithium complex oxide. Accordingly, the powder-dispersed positive electrode should be greatly improved from the viewpoint of the capacity and charge/discharge efficiency.

Some attempts have been made to improve the capacity and charge/discharge efficiency by positive electrodes or layers of positive electrode active material composed of sintered plate of lithium complex oxide. In this case, since the positive electrode or the layer of positive electrode active material contains no binder, high capacity and satisfactory charge/discharge efficiency can be expected due to a high packing density of lithium complex oxide. For example, PTL <NUM> (<CIT>) discloses a low-angle oriented positive electrode plate of an all-solid lithium battery including a solid electrolyte layer. The positive electrode plate includes multiple primary grains composed of lithium complex oxide, for example, lithium cobaltate (LiCoO<NUM>). Crystal planes (<NUM>) of the primary grains are oriented by a low mean angle of more than <NUM>° to <NUM>° relative to a main face of the positive electrode plate. Such orientation can mitigate the stress generated at an interface between the positive electrode plate and the solid electrolyte layer during charging/discharging cycles. In other words, the main face of the positive electrode plate has a low expansion-contraction rate to reduce the stress generated at the interface between the positive electrode plate and the solid electrolyte layer. Defects in the solid electrolyte layer and separation of the positive electrode plate from the solid electrolyte layer can thereby be reduced.

Negative electrodes or negative electrode active material layers are also known that are composed of lithium complex oxide sintered plates. For example, PTL <NUM> (<CIT>) discloses an all-solid battery including a positive electrode, a negative electrode, and a solid electrolyte layer. The positive electrode or negative electrode is composed of a lithium titanate (Li<NUM>Ti<NUM>O<NUM>) sintered body. The sintered body disclosed in PTL <NUM> is highly dense and has a relative denseness of <NUM>% or more. The high relative denseness reflects the general comprehension that the positive and negative electrodes are preferably dense for enhanced energy densities of all-solid secondary batteries.

Antiperovskite materials have been proposed for highly lithium-ion-conductive solid electrolytes. For example, PTL <NUM> (<CIT>) discloses that Li<NUM>OCl and Li(<NUM>-x)Mx/<NUM>OA serve as solid electrolytes having superior lithium ion conductivity, where <NUM>≤x≤<NUM>; M represents at least one element selected from the group consisting of Mg, Ca, Ba, and Sr; and A represents at least one element selected from the group consisting of F, Cl, Br, and I. NPL <NUM> (<NPL>) discloses that Li<NUM>OHX is preferred as a solid electrolyte for an all-solid secondary battery, where X represents Cl or Br. NPL <NUM> also discloses that a compound produced by doping of Li<NUM>OHCl with fluorine and partial substitution of F- for OH- has electrochemical stability suitable for the all-solid secondary battery.

All-solid lithium batteries with a solid electrolyte penetrating in the pore structure of a sintered positive electrode plate are also disclosed in documents <CIT> and <CIT>.

The present inventors had had an idea that an all-solid lithium battery with high performance could be manufactured with a low-angle oriented positive electrode plate, a negative electrode plate, and a solid electrolyte as described above, in the earliest years. Such all-solid lithium batteries had been practically manufactured. Unfortunately, it was found that some batteries among the resultant batteries might have high battery resistance and significantly poor high-rate performance. Such disadvantages were inherent in the above configuration of the all-solid lithium battery including a solid electrolyte, such as Li<NUM>OCl.

The present inventors have now found that the battery resistance and the high-rate performance during charge/discharge cycles can be remarkably improved and the production yield can be significantly enhanced in an all-solid lithium battery including a low-angle oriented positive electrode plate and a specific solid electrolyte by adjusting the porosity in the low-angle oriented positive electrode plates to <NUM> to <NUM>% and filling <NUM>% or more of the pores in the plate with the solid electrolyte.

Accordingly, an object of the present invention is to remarkably improve the battery resistance and the high-rate performance during charge/discharge cycles and to significantly enhance the production yield in an all-solid lithium battery including a low-angle oriented positive electrode plate and a specific solid electrolyte.

According to an aspect of the present invention, there is provided an all-solid lithium battery comprising:.

According to another aspect of the present invention, there is provided a method of producing the all-solid lithium battery, comprising the steps of:.

<FIG> schematically illustrates an exemplary all-solid lithium battery of the present invention. The all-solid lithium battery <NUM> shown in <FIG> includes an oriented positive electrode plate <NUM>, a solid electrolyte <NUM>, and a negative electrode plate <NUM>. The oriented positive electrode plate <NUM> is a lithium complex oxide sintered plate having a porosity of <NUM> to <NUM>%.

The lithium complex oxide sintered plate contains a plurality of primary grains composed of lithium complex oxide, and the primary grains have a mean orientation angle of more than <NUM>° to <NUM>° to a main face of the oriented positive electrode plate. This plate is a so-called "low-angle oriented positive electrode plate". The solid electrolyte <NUM> has a melting point lower than the melting point or decomposition temperature of the oriented positive electrode plate <NUM> and the negative electrode plate <NUM>. The negative electrode plate <NUM> is capable of intercalating and deintercalating lithium ions at <NUM> V or higher (vs. Li/Li+), and contains titanium (Ti). In the observation of a cross-section perpendicular to a main face of the oriented positive electrode plate <NUM>, at least <NUM>% of the pores contained in the oriented positive electrode plate <NUM> are filled with the solid electrolyte <NUM>. As described above, the battery resistance and high-rate performance during charge/discharge cycles can be remarkably improved and the production yield can be significantly enhanced in the all-solid lithium battery including a low-angle oriented positive electrode plate and a specific solid electrolyte through adjustment of the porosity in the low-angle oriented positive electrode plate to <NUM> to <NUM>% and filling <NUM>% or more of the pores in the plate with the solid electrolyte.

As described above, the present inventors had had an idea that an all-solid lithium battery with high performance could be manufactured with a low-angle oriented positive electrode plate, a negative electrode plate, and a solid electrolyte, as disclosed in PTLs <NUM> to <NUM>, in the earliest years. Such all-solid lithium batteries had been practically manufactured. Unfortunately, it was found that some batteries among the resultant batteries had high battery resistance and significantly poor high-rate performance. Although no cause of such disadvantages is clear, a plausible cause is as follows: Since a plurality of primary platy grains constituting the low-angle oriented positive electrode plate (specifically, the (<NUM>) plane of these grains) are oriented by a mean orientation angle of <NUM>° or less (e.g., about <NUM>°) to a main face of the oriented positive electrode plate, it is believed to be one of causes of the disadvantage that the surface microstructure on the oriented positive electrode plate is even (compared with the high-angle oriented or unoriented positive electrode plate), resulting in predominant exposure of the (<NUM>) plane corresponding to a main face of primary platy grain. In other words, the solid electrolyte is desired to be preliminarily softened or melted in order to increase adhesiveness at the interfaces between the positive electrode plate and the solid electrolyte and between the negative electrode plate and the solid electrolyte when batteries are manufactured using battery components as described above; however, the softened or melted electrolyte has poor wettability with the (<NUM>) plane that is predominantly exposed on the surface of the positive electrode plate, resulting in poor interfacial contact. In contrast, in the use of an unoriented positive electrode plate having random orientation angles of the primary grains, interfacial separation occurs due to the stress generated during intercalation and deintercalation of lithium ions and breakdown of batteries may occur, as disclosed in PTL <NUM>. These problems can be advantageously solved by adjustment of porosity in the low-angle oriented positive electrode plate to <NUM> to <NUM>% and filling <NUM>% or more of the pores in the plate with the solid electrolyte. That is, the battery resistance and high-rate performance during charge/discharge cycles can be remarkably improved and the production yield of batteries can be significantly enhanced. Although the mechanism providing these unexpected improvements is not clear, a plausible speculation is that the solid electrolyte penetrates into and permeates the pores in the oriented positive electrode plate, resulting in strong interfacial contact between the solid electrolyte and the planes other than the (<NUM>) plane (i.e., crystalline planes having good wettability with the solid electrolyte). In other words, since the pores have random shapes inside the oriented positive electrode plate, the solid electrolyte can sufficiently come in contact with the planes other than the (<NUM>) plane in spite of predominant exposure of the (<NUM>) plane on the surface of the oriented positive electrode plate.

As described above, in the observation of a cross-section perpendicular to a main face of the oriented positive electrode plate <NUM>, <NUM>% or more, preferably <NUM>% or more, more preferably <NUM>% or more, further more preferably <NUM>% or more of the pores contained in the oriented positive electrode plate <NUM> is filled with the solid electrolyte <NUM>. Such a filling rate can further reduce the battery resistance and improve the high-rate performance during charge/discharge cycles, and enhance the production yield of batteries. In the use of an inorganic solid electrolyte, a higher filling rate of the electrolyte is preferred in the pores of the positive electrode plate <NUM>. Although the filling rate is ideally <NUM>%, it is practically <NUM>% or less, more practically <NUM>% or less. The filling rate (%) of the electrolyte in the pores can be determined through (i) polishing of the battery with a cross section polisher (CP), (ii) SEM observation and EDX analysis of the resultant cross-section of the oriented positive electrode plate at a specific magnification (e.g., <NUM> folds) and a specific field of view (e.g., <NUM> by <NUM>), and subsequent image analysis, (iii) measurement of the area of pores filled with the solid electrolyte and the overall area of pores, and (iv) dividing the area of pores filled with the solid electrolyte by the overall area of pores and multiplying the resulting value by <NUM>.

In the observation of a cross-section perpendicular to a main face of oriented positive electrode plate <NUM>, the solid electrolyte <NUM> is in contact with preferably at least <NUM>%, more preferably at least <NUM>%, further more preferably at least <NUM>% of the outer peripheral length of pores contained in the oriented positive electrode plate <NUM>. Such a contact rate can further reduce the battery resistance and improve the high-rate performance during charge/discharge cycles, and further enhance the production yield of batteries. These advantages are presumably based on a further increase in the contact area between the solid electrolyte and the oriented positive electrode plate. In the use of an inorganic solid electrolyte, a higher contact rate of the electrolyte is preferred in the pores of positive electrode plate <NUM>. Although the contact rate is ideally <NUM>%, it is practically <NUM>% or less, more practically <NUM>% or less. The contact rate (%) between the outer periphery of pores and the solid electrolyte can be determined through (i) polishing of the battery with a cross section polisher (CP), (ii) SEM observation and EDX analysis of the resultant cross-section of the oriented positive electrode plate at a specific magnification (e.g., <NUM> folds) and a specific field of view (e.g., <NUM> by <NUM>), and subsequent image analysis, (iii) measurement of contact length between grains constituting the outer periphery of pores (i.e., grains adjacent to pores) and the solid electrolyte, and the outer peripheral length of pores, and (iv) dividing the contact length between the grains constituting the outer periphery of pores and the solid electrolyte by the outer peripheral length of pores and multiplying the resulting value by <NUM>.

In the observation of a cross-section perpendicular to a main face of oriented positive electrode plate <NUM>, the solid electrolyte <NUM> is in contact with preferably at least <NUM>%, more preferably at least <NUM>% of the planes other than the (<NUM>) plane of lithium complex oxide at the surface of pores included in the oriented positive electrode plate <NUM>. Such a contact rate can further reduce the battery resistance and improve the high-rate performance during charge/discharge cycles, and further enhance the production yield of batteries. These advantages are presumably based on the formation of superior interfacial contact due to high wettability of the planes other than the (<NUM>) plane to the solid electrolyte used in the present invention. The upper limit of the contact rate, which is in contact with the solid electrolyte <NUM>, of the planes other than the (<NUM>) plane in the lithium complex oxide is not limited. The rate is practically <NUM>% or less, more practically <NUM>% or less. The contact rate (%) between the planes other than the (<NUM>) plane and the solid electrolyte at the surface of pores can be determined through (i) polishing of the battery with a cross section polisher (CP), (ii) SEM observation, EDX analysis and EBSD measurement of the resultant cross-section of the oriented positive electrode plate at a specific magnification (e.g., <NUM> folds) and a specific field of view (e.g., <NUM> by <NUM>), (iii) determination of whether the crystal planes of grains exposed at the surface of pores are the (<NUM>) planes or the planes other than the (<NUM>) plane based on the EBSD results, and measurement of the first outer peripheral length of pores where the solid electrolyte is in contact with the planes other than the (<NUM>) plane and the second outer peripheral length of pores where the planes other than the (<NUM>) plane are exposed, and (iv) dividing the first outer peripheral length of pores where the solid electrolyte is in contact with the planes other than the (<NUM>) plane by the second outer peripheral length of pores where the planes other than the (<NUM>) plane are exposed and multiplying the resulting value by <NUM>.

The oriented positive electrode plate <NUM> is a lithium complex oxide sintered plate. The lithium complex oxide sintered plate includes a plurality of primary grains composed of lithium complex oxide having a layered rock salt structure, and the primary grains are oriented by a mean orientation angle of more than <NUM>° to <NUM>° to a main face of oriented positive electrode plate. <FIG> illustrates an exemplary cross-sectional SEM image perpendicular to a main face of the oriented positive electrode plate <NUM>, and <FIG> illustrates a cross-sectional electron backscatter diffraction (EBSD) image perpendicular to a main face of the oriented positive electrode plate <NUM>. <FIG> is an area-based histogram illustrating the distribution of orientation angles of primary grains <NUM> in the EBSD image of <FIG>. In the EBSD image shown in <FIG>, discontinuity of the crystal orientation can be observed. In <FIG>, the orientation angle of each primary grain <NUM> is determined by the shade of color, and a darker shade indicates a smaller orientation angle. The orientation angle is a tilt angle of the (<NUM>) plane of each primary grain <NUM> to a main face of the plate. In <FIG> and <FIG>, black portions inside the oriented positive electrode plate <NUM> indicate pores.

The oriented positive electrode plate <NUM> is an oriented sintered plate composed of multiple primary grains <NUM> bonded to each other. Each primary grain <NUM> is mainly in a platy shape, and may be formed in, for example, a cuboid shape, a cubic shape, and a spherical shape. The cross-sectional shape of each primary grain <NUM> may be a rectangle, a polygon other than a rectangle, a circle, an ellipse, or any other complicated shape.

Each primary grain <NUM> is composed of lithium complex oxide. The lithium complex oxide is an oxide represented by LixMO<NUM> (<NUM><x<<NUM>, M is at least one transition metal, and M typically contains at least one of Co, Ni and Mn). The lithium complex oxide has a layered rock salt structure. The layered rock salt structure is a crystal structure in which a lithium layer and a transition metal layer other than lithium are alternately stacked with an oxygen layer therebetween, i.e., a crystal structure in which a transition metal ion layer and a lithium single layer are alternately stacked with oxide ions therebetween (typically an α-NaFeO<NUM> structure, i.e., a structure in which transition metals and lithium metals are regularly disposed along the [<NUM>] axis of a cubic rock salt structure). Examples of lithium complex oxides include LixCoO<NUM> (lithium cobaltate), LixNiO<NUM> (lithium nickelate), LixMnO<NUM> (lithium manganate), LixNiMnO<NUM> (lithium nickel manganate), LixNiCoO<NUM> (lithium nickel cobaltate), LixCoNiMnO<NUM> (lithium cobalt nickel manganate), and LixCoMnO<NUM> (lithium cobalt manganate), and particularly preferably, LixCoO<NUM> (lithium cobaltate, typically LiCoO<NUM>). The lithium complex oxide may contain at least one element selected from Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Ag, Sn, Sb, Te, Ba. , Bi, and W.

As shown in <FIG> and <FIG>, the averaged value of the orientation angles, i.e., the mean orientation angle of primary grains <NUM> is more than <NUM>° to <NUM>°. This angle range provides the following advantages <NUM>) to <NUM>). <NUM>) Since each primary grain <NUM> greatly tilts from the thickness direction of the positive electrode plate, the adhesiveness between the individual primary grains can be improved. This configuration can improve the lithium ion conductivity between one primary grain <NUM> and another primary grain <NUM> adjacent on two ends of the one primary grain <NUM> in the main face direction, resulting in an improvement in high-rate performance. <NUM>) Cycle characteristics can be improved. In detail, the expansion and contraction of the oriented positive plate <NUM> accompanied by the expansion and contraction of each primary grain <NUM> in the direction perpendicular to the (<NUM>) plane depending on intercalation and deintercalation of lithium ions can be decreased in the main face direction by smaller orientation angle of the (<NUM>) plane to the main face direction, resulting in a reduction in stress generated between the oriented positive plate <NUM> and the solid electrolyte <NUM>. <NUM>) The high-rate performance can be further improved. This further improvement is caused by smooth intercalation and deintercalation of lithium ions in the oriented positive electrode <NUM>, because the expansion and contraction of oriented positive electrode plate <NUM> proceeds more dominantly in the thickness direction than in the main face direction and thereby lithium ions can intercalate and deintercalate smoothly.

The mean orientation angle of primary grains <NUM> is determined through (i) polishing of the oriented positive electrode plate with a cross section polisher (CP), (ii) EBSD analysis of the resultant cross-section of oriented positive electrode plate at a specific magnification (e.g., <NUM> folds) and a specific field of view (e.g., <NUM> by <NUM>), (iii) measurement of angles between the (<NUM>) plane of primary grains and a main face of oriented positive electrode plate (i.e., tilt of crystal orientation from the (<NUM>) plane) as orientation angles based on all grains specified in the resultant EBSD image, and (iv) averaging of all the resulting angles to be a mean orientation angle. The mean orientation angle of the primary grains <NUM> is preferably <NUM>° or less, and more preferably <NUM>° or less from the viewpoint of a further improvement in high-rate performance. The mean orientation angle of the primary grains <NUM> is preferably <NUM>° or more, and more preferably <NUM>° or more from the viewpoint of a further improvement in high-rate performance.

As shown in <FIG>, the orientation angle of each primary grain <NUM> may be widely distributed from <NUM>° to <NUM>°, and most of the orientation angles are preferably distributed in a region of more than <NUM>° to <NUM>°. In other words, when the cross-section of the oriented sintered plate constituting the oriented positive electrode plate <NUM> is analyzed in the EBSD image, the total area of primary grains <NUM> that have the orientation angle of more than <NUM>° to <NUM>° to a main face of the oriented positive electrode plate <NUM> (hereinafter, referred to as low-angle primary grains) is preferably <NUM>% or more, and more preferably <NUM>% or more of the total area of the primary grains <NUM> (specifically, <NUM> primary grains <NUM> used in calculation of the mean orientation angle) included in the cross-section. This configuration can increase the proportion of the primary grains <NUM> having higher mutual adhesiveness, thereby high-rate performance can be further improved. In addition, the total area of the low-angle primary grains having an orientation angle of <NUM>° or less is more preferably <NUM>% or more of the total area of the <NUM> primary grains <NUM> used in the calculation of the mean orientation angle. Furthermore, the total area of the low-angle primary grains having an orientation angle of <NUM>° or less is more preferably <NUM>% or more of the total area of the <NUM> primary grains <NUM> used in the calculation of the mean orientation angle.

Since each primary grain <NUM> is mainly platy, the cross-section of each primary grain <NUM> respectively extends in a predetermined direction as shown in <FIG> and <FIG>, and typically has a substantially rectangular shape. In other words, when the cross-section of the oriented sintered plate is analyzed in the EBSD image, the total area of primary grains <NUM> that have an aspect ratio of <NUM> or more among the primary grains <NUM> included in the analyzed cross-section is preferably <NUM>% or more, and more preferably <NUM>% or more of the total area of the primary grains <NUM> (specifically, <NUM> primary grains <NUM> used in calculation of the mean orientation angle) included in the cross-section. In detail, the configuration shown in the EBSD image of <FIG> can increase the mutual adhesiveness between the primary grains <NUM>, resulting in a further improvement of high-rate performance. The aspect ratio of the primary grains <NUM> is a value determined by dividing the maximum Feret diameter by the minimum Feret diameter of the primary grains <NUM>. The maximum Feret diameter is the maximum distance between two parallel straight lines by which the primary grains <NUM> are sandwiched in the EBSD image from cross-sectional observation. The minimum Feret diameter is the minimum distance between two parallel straight lines by which the primary grains <NUM> are sandwiched.

A plurality of primary grains constituting the oriented sintered plate has a mean grain diameter of preferably <NUM> or less. Specifically, the primary grains <NUM> has a mean grain diameter of preferably <NUM> or less, more preferably <NUM> or less. Such a diameter range can reduce the distance for lithium ions to travel in the primary grains <NUM>, resulting in a further improvement in high-rate performance. For example, in a charge state, the lithium ions move from the inside of primary grains <NUM> to the solid electrolyte in the pores of the positive electrode, further pass through the film-shaped (or planar) solid electrolyte <NUM> and move into the grains of negative electrode as a counter electrode. In this mechanism, since the traveling distance of lithium ions can be reduced in the positive electrode including the primary grains <NUM> where the solid electrolyte in the pores serve as a delaying factor, and thereby high-rate performance can be improved. The mean grain diameter of primary grains <NUM> can be measured by the analysis of a cross-sectional SEM image of the sintered plate. For example, the sintered plate is processed with a cross section polisher (CP) to expose a polished cross-section. The polished cross-section is observed by SEM (scanning electron microscopy) at a specific magnification (e.g., <NUM> folds) and a specific field of view (e.g., <NUM> by <NUM>). In this case, the field of view is selected such that <NUM> or more primary grains are located in this field. In the resultant SEM image, circumscribed circles are drawn for all primary grains and the diameters of circumscribed circles are measured and averaged to be a mean grain diameter of primary grains.

The lithium complex oxide sintered plate constituting the oriented positive electrode plate <NUM> has a porosity of <NUM> to <NUM>%. Such a porosity range can sufficiently fill the pores in the oriented positive electrode plate <NUM> with the solid electrolyte <NUM>, resulting in a significant reduction in the battery resistance and an improvement in the high-rate performance during charge/discharge cycles, and a remarkable enhancement in the production yield of batteries. The porosity in the oriented positive electrode plate <NUM> indicates the volume rate of pores in the oriented positive electrode plate <NUM>. This porosity can be determined by the analysis in a cross-sectional SEM image of the oriented positive electrode plate. For example, the porosity (%) can be determined through (i) processing of the sintered plate with a cross section polisher (CP) to expose a polished cross-section, (ii) scanning electron microscope (SEM) observation of the polished cross-section at a specific magnification (e.g., <NUM> folds) and a specific field of view (e.g., <NUM> by <NUM>), and (iii) analysis of the resultant SEM image, and dividing the total area of all the pores in the field of view by the total area (i.e., cross-sectional area) of the sintered plate in the field of view and further multiplying the resulting value by <NUM>.

The oriented positive electrode plate <NUM> has a thickness of <NUM> or more, preferably <NUM> or more, particularly preferably <NUM> or more, most preferably <NUM> or more from the viewpoint of an increase in the active material capacity per unit area and an increase in energy density of the all-solid lithium battery <NUM>. The upper limit of the thickness is not limited. The oriented positive electrode plate <NUM> has a thickness of preferably less than <NUM>, more preferably less than <NUM>, further more preferably <NUM> or less, particularly preferably <NUM> or less, particularly more preferably <NUM> or less, most preferably <NUM> or less, <NUM> or less, or <NUM> or less from the viewpoint of restraint in deterioration of battery properties (particularly, an increase in electrical resistance) due to repeated charge/discharge cycles. In addition, the oriented positive electrode plate has dimensions of preferably <NUM> by <NUM> or more, more preferably <NUM> by <NUM> or more. In another expression, the oriented positive electrode plate has an area of preferably at least <NUM><NUM>, more preferably at least <NUM><NUM>.

A face, remote from the solid electrolyte <NUM>, of the oriented positive electrode plate <NUM> is preferably provided with a positive electrode collector <NUM>. In addition, a face, remote from the solid electrolyte <NUM>, of the negative electrode plate <NUM> is preferably provided with a negative electrode collector <NUM>. Examples of the material constituting the positive electrode collector <NUM> and the negative electrode collector <NUM> include platinum (Pt), platinum (Pt)/palladium (Pd), gold (Au), silver (Ag), aluminum (Al), copper (Cu), and ITO (indium-tin oxide film).

The oriented positive electrode plate <NUM>, the solid electrolyte <NUM>, and the negative electrode plate <NUM> are accommodated in a container <NUM>. The container <NUM> may be of any type that can accommodate a unit cell or a laminated battery that a plurality of the unit cells is stacked in series or in parallel. In particular, since an all-solid lithium battery <NUM> has no risk of electrolyte leakage, the container <NUM> may be of a relatively simple type, and the cell or battery may be packaged with a cover material. For example, the all-solid lithium battery can be manufactured in a chip form for mounting on an electronic circuit or in a laminate cell form (e.g., a multilayer product of aluminum (Al)/polypropylene (PP)) for low-profile and broad space applications. The positive electrode collector <NUM> and/or the negative electrode collector <NUM> may have a structure that can serve as a part of the container <NUM>. In order to further increase the heat resistance, a heat-resistant resin, such as polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), polyimide, and polyamide, may be used in place of polypropylene, and a metal, for example, aluminum or stainless steel, may also be used after ensuring insulation between the cover material and the collector.

The solid electrolyte <NUM> is a lithium ion conductive material having a melting point lower than the melting point or pyrolytic temperature of the oriented positive electrode plate <NUM> or the negative electrode plate <NUM>. The solid electrolyte <NUM> typically has a higher melting point than the operational temperature of the battery, and specifically has a melting point higher than the operational temperature of the battery and not higher than <NUM>. Since such a solid electrolyte <NUM> has a low melting point, the solid electrolyte can melt at a temperature of <NUM> to <NUM> and permeate into the pores of the oriented positive electrode plate <NUM> and the pores of the negative electrode plate <NUM> if desired, as described later, resulting in strong interfacial contact.

According to the invention, the solid electrolyte <NUM> is represented by the formulas specified in claim <NUM>. In other embodiments, which do not form part of the invention, the solid electrolyte <NUM> may contain a different lithium halide-based material. Examples of the lithium halide-based materials include one selected from the group consisting of Li<NUM>OCl, Li(<NUM>-x)Mx/<NUM>OA (where <NUM>≤x≤<NUM>, M is at least one selected from the group consisting of Mg, Ca, Ba and Sr, and A is at least one selected from the group consisting of F, Cl, Br and I), Li<NUM>(OH)<NUM>-aFaCl (where <NUM>≤a≤<NUM>), and Li<NUM>OHX (where X is Cl and/or Br), and Li<NUM>OCl or Li<NUM>(OH)<NUM>F<NUM>Cl. According to the invention, a preferred example of the solid electrolyte <NUM> includes a lithium halide-based material that has a formula Lia(OH)bFcBr (where <NUM>≤a≤<NUM>, b=a-c-<NUM>, and <NUM>≤c≤<NUM>) and an antiperovskite crystal phase, for example, Li<NUM>(OH)<NUM>F<NUM>Br. Alternatively, in embodiments not forming part of the invention, the solid electrolyte <NUM> may be a material other than the lithium halide-based material. According to the invention, the solid electrolyte may be a material that has a formula xLiOH-yLi<NUM>SO<NUM> (where x+y=<NUM>, and <NUM>≤x≤<NUM>), such as 3LiOH·Li<NUM>SO<NUM>. Each material as described above is advantageous in high ion conductivity.

A typical form of the solid electrolyte <NUM> is a solid electrolyte layer. The solid electrolyte layer can be produced by any process. Suitable examples of such processes include vapor phase deposition, such as sputtering and CVD; liquid phase deposition, such as screen printing and spin coating; compression of powder; heating of a raw material to a temperature above the melting point and then solidification of the melt; and heating of compressed raw powder to a temperature above the melting point and then solidification of the melt.

Since the solid electrolyte <NUM> has a low melting point as described above, the solid electrolyte can melt at a temperature of <NUM> to <NUM> and permeate into the pores of the oriented positive electrode plate <NUM> and the pores of the negative electrode plate <NUM> if desired, as described later, resulting in strong interfacial contact. According to the invention, the solid electrolyte <NUM> is preferably a melt-solidified material composed of xLiOH·yLi<NUM>SO<NUM> (where x+y=<NUM>, and <NUM>≤x≤<NUM>). According to another embodiment, which is not part of the invention, the electrolyte is a melt-solidified material composed of Li<NUM>OCl. According to other embodiments, which are not part of the invention, the solid electrolyte <NUM> may be one melt-solidified material selected from the group consisting of Li<NUM>OCl, Li(<NUM>-x)Mx/<NUM>OA (where <NUM>≤x≤<NUM>, M is at least one selected from the group consisting of Mg, Ca, Ba and Sr, and A is at least one selected from the group consisting of F, Cl, Br and I), Li<NUM>(OH)<NUM>-aFaCl (where <NUM>≤a≤<NUM>), and Li<NUM>OHX (where X is Cl and/or Br). According to the invention, the solid electrolyte <NUM> is preferably a melt-solidified material that has a formula Lia(OH)bFcBr (where <NUM>≤a≤<NUM>, b=a-c-<NUM>, and <NUM>. <NUM>≤c≤<NUM>) and an antiperovskite crystal phase.

The solid electrolyte <NUM> may have any dimension. The solid electrolyte has a thickness of preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, further more preferably <NUM> to <NUM> in a region other than the permeated portion of the solid electrolyte into the pores of the oriented positive electrode plate <NUM> and the pores of the negative electrode plate <NUM> from the viewpoint of high-rate performance during charge/discharge cycles and mechanical strength. The thickness of the solid electrolyte layer may be controlled by a layering process, or with spacers in the case of heating of compressed raw powder to a temperature above the melting point and then solidification of the melt. In other words, the all-solid lithium battery preferably includes spacers for defining the thickness of the solid electrolyte layer <NUM> between the oriented positive electrode plate <NUM> and the negative electrode plate <NUM>. The spacers have an electrical resistivity of preferably <NUM>×<NUM><NUM> Ω·cm or more, and more preferably <NUM>×<NUM><NUM> Ω·cm or more. The spacers are composed of any material, preferably composed of ceramic, such as Al<NUM>O<NUM>, MgO, and ZrO<NUM>.

The negative electrode plate <NUM> can intercalate and deintercalate lithium ions at <NUM> V or more based on Li/Li+ and contains Ti. A preferred negative electrode active material satisfying such conditions is an oxide containing at least Ti. Preferred examples of such a negative electrode active material include lithium titanate Li<NUM>Ti<NUM>O<NUM> (hereinafter referred to as "LTO"), niobium titanium complex oxide Nb<NUM>TiO<NUM>, and titanium oxide TiO<NUM>. More preferred examples of the negative electrode active material include LTO and Nb<NUM>TiO<NUM>. A further preferred example of the negative electrode active material is LTO. Typical LTO is known to have a spinel structure. Alternatively, LTO may have a different structure during the charging/discharging cycles of the battery. For example, LTO may have two phases consisting of Li<NUM>Ti<NUM>O<NUM> having a spinel structure and Li<NUM>Ti<NUM>O<NUM> having a rock-salt structure during the charging/discharging cycles, and the reaction continues between the two phases. Thus, LTO may have any structure other than the spinel structure.

The negative electrode plate <NUM> is preferably composed of a sintered plate containing, for example, LTO or Nb<NUM>TiO<NUM>. Since the negative electrode plate composed of a sintered plate contains no binder, high capacity and satisfactory charge/discharge efficiency can be achieved due to a high packing density of the negative-electrode active material, for example, LTO or Nb<NUM>TiO<NUM>. The binder in the green sheet will eventually disappear or burn while the green sheet is fired into the negative electrode plate. The LTO sintered plate can be produced by a process disclosed in PTL <NUM> (<CIT>).

The negative electrode plate <NUM> may have high compactness or some pores. The pores, if contained, in the negative electrode plate can sufficiently (or uniformly) release the stress generated by the expansion and contraction of crystal lattices accompanied by the intercalation and deintercalation of lithium ions in the charge/discharge cycles, resulting in an effective reduction in cracking at grain boundaries accompanied by repeated charge/discharge cycles.

The negative electrode plate <NUM> has a porosity of preferably <NUM> to <NUM>%, more preferably <NUM> to <NUM>%. Such a porosity range can desirably achieve the stress relaxation by the pores and high energy capacity. The porosity of the negative electrode plate <NUM> is a volume rate of the pores in the negative electrode plate <NUM>, and can be determined by the analysis of a cross-sectional SEM image of the negative electrode plate <NUM> similar to the porosity of the oriented positive electrode plate <NUM> as described above.

In the observation of a cross-section perpendicular to a main face of the negative electrode plate <NUM>, the solid electrolyte <NUM> occupies <NUM>% or more, preferably <NUM>% or more, more preferably <NUM>% or more, further more preferably <NUM>% or more of the pores contained in the negative electrode plate <NUM>. Such a filling rate can further reduce the battery resistance and improve the high-rate performance during charge/discharge cycles, and further enhance the production yield of batteries. In the use of an inorganic solid electrolyte, a higher filling rate of the electrolyte is preferred in the pores of the positive electrode plate <NUM>. Although the filling rate is ideally <NUM>%, it is practically <NUM>% or less, more practically <NUM>% or less. The filling rate (%) of the electrolyte in the pores can be determined through the analysis of the cross-sectional SEM image of the negative electrode plate <NUM>, as in the analysis of the oriented positive electrode plate <NUM> as described above.

In the observation of a cross-section perpendicular to a main face of the negative electrode plate <NUM>, the solid electrolyte <NUM> is in contact with preferably at least <NUM>%, more preferably at least <NUM>%, further more preferably at least <NUM>% of the outer peripheral length of the pores contained in the negative electrode plate <NUM>. Such a contact rate can further reduce the battery resistance and improve the high-rate performance during charge/discharge cycles, and further enhance the production yield of batteries. Accordingly, the contact area further increases between the solid electrolyte and the negative electrode plate. In the use of an inorganic solid electrolyte, a higher contact rate of the electrolyte is preferred in the pores of the negative electrode plate <NUM>. Although the contact rate is ideally <NUM>%, it is practically <NUM>% or less, more practically <NUM>% or less. The contact rate (%) between the outer periphery of the pores and the solid electrolyte can be determined through the analysis of the cross-sectional SEM image of the negative electrode plate <NUM>, as in the analysis of the oriented positive electrode plate <NUM> as described above.

The negative electrode plate <NUM> has a thickness of <NUM> or more, preferably <NUM> or more, more preferably <NUM> or more, particularly preferably <NUM> or more, mostly preferably <NUM> or more from the viewpoint of an increase in the active material capacity per unit area and an increase in energy density of the all-solid lithium battery <NUM>. The thickness of the negative electrode plate <NUM> may have any upper limit. The negative electrode plate <NUM> has a thickness of preferably <NUM> or less, more preferably <NUM> or less to reduce the deterioration of the battery properties accompanied by repeated charge/discharge cycles (particularly, due to an increase in electric resistance). In addition, the negative electrode plate <NUM> has dimensions of preferably <NUM> by <NUM> or more, more preferably <NUM> by <NUM> or more. In another expression, the negative electrode plate <NUM> has an area of preferably at least <NUM><NUM>, more preferably at least <NUM><NUM>.

As described above, the oriented positive electrode plate <NUM> is preferably a LiCoO<NUM> (LCO) sintered plate, and the negative electrode plate <NUM> is preferably a Li<NUM>Ti<NUM>O<NUM> (LTO) sintered plate. In particular, an averaged value of the orientation angles, i.e., a mean orientation angle of more than <NUM>° to <NUM>° in the LCO oriented positive electrode plate causes no expansion and contraction to occur in the main face direction during charge/discharge cycles, and the LTO negative electrode plate and the solid electrolyte also do not expand and contract during the charge/discharge cycles, resulting in no stress generation (in particular, the stress at the interface between the oriented positive electrode plate <NUM> or negative electrode plate <NUM> and the solid electrolyte <NUM>) and stable charge and discharge. In the use of Nb<NUM>TiO<NUM> sintered plate in the negative electrode plate <NUM>, primary grains constituting the Nb<NUM>TiO<NUM> sintered plate are preferably oriented to reduce the expansion and contraction.

Although being capable of charging or discharging at room temperature, the all-solid lithium battery of the present invention preferably charges or discharges at <NUM> or more. A temperature of <NUM> or more can achieve rapid charge/discharge at a high cycle capacity retention rate. In other words, a temperature of <NUM> or more enables the all-solid lithium battery <NUM> to rapidly charge or discharge. That is, the all-solid lithium battery can run stably at a high rate at this temperature. Repeated charge/discharge can retain high capacity. In other words, a high cycle capacity retention rate can be achieved. The operational temperature of the all-solid lithium battery during the charge/discharge cycles is preferably <NUM> or more, more preferably <NUM> to <NUM>, further preferably <NUM> to <NUM>, particularly preferably <NUM> to <NUM>. Examples of a heating means achieving such an operational temperature include various heaters and exothermic devices. Preferred examples of the heating means are electroconductive ceramic heaters. In other words, the all-solid lithium battery of this embodiment is preferably provided as a secondary battery system including a heating means.

The inventive all-solid lithium battery <NUM> is preferably produced as follows: Solid electrolyte powder containing at least one selected from the group consisting of xLiOH·yLi<NUM>SO<NUM> and Lia(OH)bFcBr is placed on the oriented positive electrode plate <NUM> (or the negative electrode plate <NUM>). The negative electrode plate <NUM> (or the oriented positive electrode plate <NUM>) is placed on the solid electrolyte powder. The negative electrode plate <NUM> is pressed toward the oriented positive electrode plate <NUM> (or the oriented positive electrode plate is pressed toward the negative electrode plate) at <NUM> to <NUM>, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM> to melt the solid electrolyte powder and permeate the melt into the pores in the oriented positive electrode plate. This press treatment is performed by any process that can generate a load, for example, a mechanical load or weight. Subsequently, the oriented positive electrode plate <NUM>, the molten electrolyte, and the negative electrode plate <NUM> are spontaneously or controllably cooled to solidify the molten electrolyte into the solid electrolyte <NUM>.

As described above, the all-solid lithium battery <NUM> may include spacers that define the thickness of the solid electrolyte layer <NUM> between the oriented positive electrode plate <NUM> and the negative electrode plate <NUM>. This configuration is preferably achieved by disposing spacers along with the solid electrolyte powder between the oriented positive electrode plate <NUM> and the negative electrode plate <NUM>.

The present invention will be described in more detail by the following examples. In the following examples, LiCoO<NUM> is abbreviated as "LCO" and Li<NUM>Ti<NUM>O<NUM> is abbreviated as "LTO". Only examples <NUM>-<NUM>, <NUM> and <NUM> are according to the invention. All other examples are not according to the invention.

Co<NUM>O<NUM> powder (available from Seido Chemical Co. , a mean particle size of <NUM>) and Li<NUM>CO<NUM> powder (available from The Honjo Chemical Corporation) were weighed into a Li/Co molar ratio of <NUM>, mixed, and then heated at <NUM> for five hours. The resultant powder was pulverized in a pot mill into a volume-based D50 of <NUM>, to give LCO powder composed of platy particles. The resultant LCO powder (<NUM> parts by weight), a dispersive medium (toluene:<NUM>-propanol = <NUM>:<NUM>) (<NUM> parts by weight), a binder (polyvinyl butyral: Product No. BM-<NUM>, available from Sekisui Chemical Co. ) (<NUM> parts by weight), a plasticizer (di-<NUM>-ethylhexyl phthalate (DOP), available from Kurogane Kasei Co. ) (<NUM> parts by weight), and a dispersant (product name: RHEODOL SP-O30, available from Kao Corporation) (<NUM> parts by weight) were mixed. The mixture was defoamed by stirring under reduced pressure to prepare an LCO slurry with a viscosity of <NUM> cP. The viscosity was measured with an LVT viscometer available from Brookfield. The slurry was molded into an LCO green sheet onto a PET film by a doctor blade process. The dried thickness of the LCO green sheet was <NUM>.

Li<NUM>CO<NUM> raw material powder (volume-based particle diameter D50: <NUM>, available from The Honjo Chemical Corporation) (<NUM> parts by weight), a binder (poly(vinyl butyral): Product No. BM-<NUM>, available from Sekisui Chemical Co. ) (<NUM> parts by weight), a plasticizer di-<NUM>-ethylhexyl phthalate (DOP), available from Kurogane Kasei Co. ) (<NUM> parts by weight), and a dispersant (RHEODOL SP-O30, available from Kao Corporation) (<NUM> parts by weight) were mixed. The mixture was defoamed by stirring under reduced pressure to prepare a Li<NUM>CO<NUM> slurry with a viscosity of <NUM> cP. The viscosity was measured with an LVT viscometer available from Brookfield. The Li<NUM>CO<NUM> slurry was molded into a Li<NUM>CO<NUM> green sheet on a PET film by a doctor blade process. The dried thickness of the Li<NUM>CO<NUM> green sheet was adjusted such that the Li/Co molar ratio of the Li content in the Li<NUM>CO<NUM> green sheet to the Co content in the LCO green sheet was <NUM>.

The LCO green sheet was separated from the PET film, and was cut into a <NUM> square. The cut piece was placed on the center of a bottom magnesia setter (dimensions: <NUM> square, height: <NUM>). The LCO green sheet was heated to <NUM> at a heating rate of <NUM>/h, and was degreased for three hours. The LCO green sheet was then kept at <NUM> for three hours to calcine the LCO green sheet. The dried Li<NUM>CO<NUM> green sheet was cut into a size such that the Li/Co molar ratio of the Li content in the Li<NUM>CO<NUM> green sheet to the Co content in the calcined LCO plate was <NUM>. The cut piece of the Li<NUM>CO<NUM> green sheet, as an excess-lithium source, was placed on the calcined LCO plate, and a porous top magnesia setter was placed thereon. The calcined LCO plate and the green sheet piece disposed between the top and bottom setters were placed into an alumina sheath of a <NUM> square (available from Nikkato Co. At this time, the alumina sheath was not tightly sealed, and was covered with a lid with a gap of <NUM>. The laminate was heated to <NUM> at a heating rate of <NUM>/h, and was degreased for three hours. The laminate was then heated to <NUM> at <NUM>/h, and was kept for five hours. The laminate was then heated to <NUM> at <NUM>/h, and was kept for <NUM> hours to fire. After the firing, the fired laminate was cooled to room temperature, and was removed from the alumina sheath. Thus, the sintered LCO plate was yielded as a positive electrode plate. An Au film (a thickness of <NUM>) as a current collecting layer was deposited by sputtering on a face, in contact with the bottom setter, of the sintered LCO plate, and the LCO positive electrode plate was then cut into a <NUM> by <NUM> square by a laser process.

LTO powder (a volume-based D50 particle size of <NUM>, available from Sigma-Aldrich <CIT> parts by weight ), a dispersion medium (toluene: <NUM>-propanol = <NUM>:<NUM>) (<NUM> parts by weight), a binder (poly(vinyl butyral): product number BM-<NUM>, available from Sekisui Chemical Co. ) (<NUM> parts by weight), a plasticizer (DOP: di(<NUM>-ethylhexyl) phthalate, available from Kurogane Kasei Co. ) (<NUM> parts by weight), and a dispersant (product name: Rheodor SP-O30, available from Kao Corporation) (<NUM> parts by weight) were mixed. The resultant mixture of raw materials for the negative electrode was stirred and defoamed under reduced pressure, and then the viscosity was adjusted to <NUM> cP to prepare LTO slurry. The viscosity was measured with an LVT viscometer available from Brookfield. The resulting slurry was applied onto a PET film by a doctor blade process into an LTO green sheet. The dried thickness of LTO green sheet was adjusted such that the fired thickness was <NUM>.

The resultant green sheet was cut into a <NUM> square with a box knife and placed onto an embossed zirconia setter. The green sheet on the setter was placed into an alumina sheath and held at <NUM> for five hours, then heated at a rate of <NUM>/h and fired at <NUM> for five hours. An Au film (a thickness of <NUM>) as a current collecting layer was deposited on a face, in contact with the setter, of the resultant LTO sintered plate by sputtering, and the LTO sintered plate was then cut into a <NUM> by <NUM> by a laser process.

An aqueous raw material solution was prepared by dissolving of LiOH (<NUM>) and LiCl (<NUM>) into a small amount of deionized water. Each amount of these precursors was determined such that the stoichiometric ratio corresponded to the reactant formula: Li<NUM>OCl + H<NUM>O. Most of the water was removed with a rotary evaporator and a bath at about <NUM>. The resulting solid was placed in an alumina boat. The boat was disposed in an electric furnace and heated in vacuum at about <NUM> for about <NUM> hours to give Li<NUM>OCl powder, which is a reaction product, as a solid electrolyte.

The Li<NUM>OCl powder was placed on the positive electrode plate; the positive electrode plate and the Li<NUM>OCl powder were heated at <NUM> on a hot plate; and the negative electrode plate was placed while being pressed from the top. At this time, the Li<NUM>OCl powder was melted followed by solidification, and a solid electrolyte layer having a thickness of <NUM> was thereby formed. The unit cells composed of the positive electrode plate, the solid electrolyte and the negative electrode plate were used to prepare <NUM> laminated batteries.

The following properties were evaluated on the LCO positive electrode plate synthesized in Procedure (<NUM>), the LTO negative electrode plate synthesized in Procedure (<NUM>), and the battery prepared in Procedure (<NUM>).

Each of the LCO positive electrode plate and the LTO negative electrode plate was polished with a cross section polisher (CP) (IB-15000CP, available from JEOL Ltd. ), and the resultant cross-section of the electrode plate was observed with a SEM (JSM6390LA, available from JEOL Ltd. ) at a <NUM>-fold field of view (<NUM> by <NUM>). The image analysis was then performed, and the porosity (%) of each electrode plate was determined through dividing the area of all the pores by the total area of each plate and multiplying the resulting value by <NUM>.

The sintered LCO plate was polished with a cross section polisher (CP) (IB-15000CP, available from JEOL Ltd. ), and the resultant cross-section of the positive electrode plate (cross-section perpendicular to a main face of the positive electrode plate) was subjected to the EBSD measurement at a <NUM>-fold field of view (<NUM> by <NUM>) to give an EBSD image. This EBSD measurement was performed using a Schottky field emission scanning electron microscope (model JSM-7800F, available JEOL Ltd. For all grains identified in the resultant EBSD image, the angle defined by the (<NUM>) plane of the primary grain and the main face of the positive electrode plate (that is, the tilt of the crystal orientation from the (<NUM>) plane) is determined as a tilt angle. The mean value of the angles was determined as a mean orientation angle (i.e., a mean tilt angle) of the primary grains.

The prepared battery was polished with a cross section polisher (CP) (IB-15000CP, available from JEOL Ltd. ), and the resultant cross-section of the positive electrode plate or negative electrode plate was observed with a SEM (JSM6390LA, available from JEOL Ltd. ) and analyzed with an EDX at a <NUM>-fold field of view (<NUM> by <NUM>). The image analysis was then performed, and the area of the pores filled with the solid electrolyte and the area of all pores were measured, the area of all pores being the total area of the area of the pores filled with the solid electrolyte and the area of the pores not filled with the solid electrolyte. The filling rate of electrolyte (%) in the pores was determined through dividing the area of the pores filled with the solid electrolyte by the area of all the pores and multiplying the resulting value by <NUM>.

The prepared battery was polished with a cross section polisher (CP) (IB-15000CP, available from JEOL Ltd. ), and the resultant cross-section of the positive electrode plate or negative electrode plate was observed with a SEM (JSM6390LA, available from JEOL Ltd. ) and analyzed with an EDX at a <NUM>-fold field of view (<NUM> by <NUM>). The image analysis was then performed, and the contact length between the grains constituting the outer periphery of the pores (i.e., grains adjacent to the pores) and the solid electrolyte and the outer peripheral length of the pores was measured, the outer peripheral length being the total length of the contact length between the grains constituting the outer periphery of pores and the solid electrolyte, and the non-contact length between the grains constituting the outer periphery of pores and the solid electrolyte. The contact rate (%) between the outer periphery of pores and the solid electrolyte was determined thorough dividing the contact length between the grains constituting the outer periphery of pores and the solid electrolyte by the outer peripheral length of pores and multiplying the resulting value by <NUM>.

The prepared battery was polished with a cross section polisher (CP) (IB-15000CP, available from JEOL Ltd. ), and the resultant cross-section of the positive electrode plate was observed with a SEM (JSM6390LA, available from JEOL Ltd. ), analyzed with an EDX and measured with an EBSD at a <NUM>-fold field of view (<NUM> by <NUM>). The EBSD measurement was performed as in the measurement of the mean orientation angle of primary grains as described above. Whether the crystal planes of grains exposed at the surface of pores are the (<NUM>) planes or the planes other than the (<NUM>) plane was determined, and the first outer peripheral length of pores where the solid electrolyte is in contact with the planes other than the (<NUM>) plane and the second outer peripheral length of pores where the planes other than the (<NUM>) plane are exposed are measured based on the EBSD results. The contact rate (%) between the planes other than (<NUM>) plane and the solid electrolyte at the surface of pores was determined through dividing the first outer peripheral length of pores where the solid electrolyte is in contact with the planes other than the (<NUM>) plane by the second outer peripheral length of pores where the planes other than the (<NUM>) plane are exposed and multiplying the resulting value by <NUM>.

Each battery resistance of <NUM> prepared batteries was measured by AC impedance spectroscopy using an electrochemical measurement system SP-<NUM> available from BioLogic. The minimum value among <NUM> batteries was defined as the reference resistance. The batteries having a resistance value within ten times the reference resistance were determined to be non-defective products, and the number of non-defective products was defined as the production yield of batteries.

For the batteries determined to be non-defective products, the cycle capacity retention of the battery was measured in a potential range of <NUM> V to <NUM> V at a battery operational temperature of <NUM> in accordance with the following procedures.

Batteries were prepared and evaluated as in Example <NUM> except that a Li<NUM>CO<NUM> green cut sheet was not placed on the LCO calcined plate in Procedure (1c).

Batteries were prepared and evaluated as in Example <NUM> except that the keeping at <NUM> for five hours was not performed during the firing in Procedure (1c) and the heating was performed at <NUM> in Procedure (<NUM>).

Batteries were prepared and evaluated as in Example <NUM> except that the Co<NUM>O<NUM> powder having a D50 particle size of <NUM> was used in Procedure (1a).

Batteries were prepared and evaluated as in Example <NUM> except that the Li/Co ratio was <NUM> in Procedure (1b) and the firing time at <NUM> was <NUM> hours in Procedure (1c).

Batteries were prepared and evaluated as in Example <NUM> except that positive electrode plates and negative electrode plates were produced as follows:.

In Procedure (1c), an LCO sintered plate was produced as in Example <NUM> except that the Li/Co ratio, which is the molar ratio of the Li content in the Li<NUM>CO<NUM> green sheet to the Co content in the LCO calcined plate, was <NUM> and the firing was performed at a maximum temperature of <NUM>.

In Procedure (2a), an LTO sintered plate was produced as in Example <NUM> except that another LTO powder (a volume-based D50 particle size of <NUM>, available from Ishihara Sangyo Co. ) was used in the LTO raw powder.

Batteries were prepared and evaluated in Example <NUM> except that a LiOH·Li<NUM>SO<NUM>-based powder produced as follows was used in the solid electrolyte, and the batteries were prepared as follows:.

Commercially available LiOH (purity ≥ <NUM>%) and Li<NUM>SO<NUM> (purity ≥ <NUM>%) were provided. These raw materials are weighed into a LiOH:Li<NUM>SO<NUM> molar ratio of <NUM>:<NUM> and mixed in an Ar atmospheric glove box having a dew point of -<NUM> or lower. The mixture was placed in a glass tube in an Ar atmosphere and melted by heating at <NUM> for two hours. The glass tube was then placed into water and kept for ten minutes, and the melt was quenched to form a solidified material. The solidified material was then pulverized in a mortar in an Ar atmosphere to give 3LiOH·Li<NUM>SO<NUM> powder, which is a solid electrolyte.

A LiOH·Li<NUM>SO<NUM>-based powder containing ZrO<NUM> beads (<NUM> wt%) having a diameter of <NUM> was placed on the positive electrode plate, and the negative electrode plate was then placed on the powder. A weight (<NUM>) was then placed on the negative electrode plate and the laminate was heated at <NUM> for <NUM> minutes in an electric furnace. In this heating, the LiOH·Li<NUM>SO<NUM>-based powder was melted followed by solidification to thus form a solid electrolyte layer having a thickness of <NUM>. The resulting unit cells composed of the positive electrode plate, the solid electrolyte, and the negative electrode plate were used to produce <NUM> laminated batteries.

Batteries were prepared and evaluated as in Example <NUM> except that positive and negative electrode plates prepared as in Example <NUM> were used.

Batteries were prepared and evaluated as in Example <NUM> except that positive electrode plates prepared as in Example <NUM> were used and the negative electrode plates were produced as follows:.

An LTO sintered plate was produced as in Example <NUM> except that the firing was performed for five hours at a maximum temperature of <NUM> in Procedure (2b).

Batteries were prepared and evaluated as in Example <NUM> except that the thickness of the LCO sintered plate was <NUM> and the thickness of the LTO sintered plate was <NUM>.

Batteries were prepared and evaluated as in Example <NUM> except that positive and negative electrode plates were produced as in Example <NUM>.

Batteries were prepared and evaluated as in Example <NUM> except that positive and negative electrode plates were produced as in Example <NUM>, and Li(OH)<NUM>F<NUM>Cl-based powder produced as follows was used in the solid electrolyte, and the solid electrolyte powder was heated at <NUM> for <NUM> minutes in Procedure (<NUM>).

Commercially available LiOH (purity ≥ <NUM>%), LiCl (purity ≥ <NUM>%) and LiF (purity = <NUM>%) were provided as raw materials. In an Ar atmospheric glove box having a dew point of - <NUM> or lower, each raw material was weighed into a LiOH:LiCl:LiF molar ratio of <NUM>:<NUM>:<NUM> and mixed. The resultant mixed powder was transferred into a crucible made of alumina (purity = <NUM>%), and the crucible was placed in a quartz tube and sealed with a flange. This quartz tube was fixed in a tubular furnace and heated at <NUM> for <NUM> minutes. During this heating, an Ar gas having a dew point of -<NUM> or lower was injected through a gas inlet at the flange and discharged from a gas outlet, and the mixed powder was stirred. After cooling, the gas inlet and the gas outlet were closed, and the quartz tube was returned into the Ar atmospheric glove box having a dew point of -<NUM> or lower and the crucible was recovered. The reactant composite was collected from the crucible and pulverized in a mortar to give Li<NUM>(OH)<NUM>F<NUM>Cl powder, which is a solid electrolyte. In this process, the heating temperature and time in an Ar gas atmosphere can be modified as appropriate. In general, the heating temperature should be <NUM> to <NUM>, and the heating time should be <NUM> hours or longer.

Batteries were prepared and evaluated as in Example <NUM> except that positive and negative electrode plates were produced as in Example <NUM>, Li(OH)<NUM>F<NUM>Br-based powder produced as follows was used in the solid electrolyte, and the solid electrolyte powder was heated at <NUM> for <NUM> minutes in Procedure (<NUM>).

Commercially available LiOH (purity ≥ <NUM>%), LiBr (purity ≥ <NUM>%) and LiF (purity = <NUM>%) were provided as raw materials. In an Ar atmospheric glove box having a dew point of - <NUM> or lower, each raw material was weighed into a LiOH:LiBr:LiF molar ratio of <NUM>:<NUM>:<NUM> and mixed. The resultant mixed powder was transferred into a crucible made of alumina (purity = <NUM>%), and the crucible was placed in a quartz tube, and sealed with a flange.

This quartz tube was fixed in a tubular furnace and heated at <NUM> for <NUM> minutes. During this heating, an Ar gas having a dew point of -<NUM> or lower was injected through a gas inlet at the flange and discharged from a gas outlet, and the mixed powder was stirred. After cooling, the gas inlet and the gas outlet were closed, and the quartz tube was returned into the Ar atmospheric glove box having a dew point of -<NUM> or lower and the crucible was recovered. The reactant composite was collected from the crucible and pulverized in a mortar to give Li<NUM>(OH)<NUM>F<NUM>Br powder, which is a solid electrolyte. In this process, the heating temperature and time in an Ar gas atmosphere can be changed as appropriate. In general, the heating temperature should be <NUM> to <NUM>, and the heating time should be <NUM> hours or longer.

Batteries were prepared and evaluated as in Example <NUM> except that positive electrode plates were produced as follows:.

Commercially available Co<NUM>O<NUM> powder (a mean particle size D50 of <NUM>), Li<NUM>CO<NUM> powder, Ni(OH)<NUM> powder, and MnCO<NUM> powder were weighed into a molar ratio of Li(Co<NUM>Ni<NUM>Mn<NUM>)O<NUM> and mixed. The mixture was heated at <NUM> for five hours to give calcined powder. The calcined powder was pulverized in a pot mill into a mean particle size D50 of <NUM>. The resultant powder (<NUM> parts by weight), a dispersive medium (toluene:<NUM>-propanol = <NUM>:<NUM>) (<NUM> parts by weight), a binder (<NUM> parts by weight), a plasticizer (<NUM> parts by weight), and a dispersant (<NUM> parts by weight) were mixed. The resultant mixture was defoamed by stirring under reduced pressure to prepare an Li(Co,Ni,Mn)O<NUM> slurry with an adjusted viscosity. The slurry as prepared above was shaped into a green sheet onto a PET film by a doctor blade process. The thickness of the LCO green sheet was adjusted such that the fired thickness was <NUM>.

The Li(Co,Ni,Mn)O<NUM> green sheet separated from the PET film was cut out. A cut piece of green sheet was placed on the center of a bottom magnesia setter, and a porous top magnesia setter was placed on the piece. The cut piece of green sheet sandwiched between two setters was placed in an alumina sheath. In this step, the alumina sheath was loosely capped with a small gap. The resultant laminate was heated to <NUM> at a rate of <NUM>/h, degreased for three hours, and then fired at <NUM> for <NUM> hours to give a Li(Co,Ni,Mn)O<NUM> sintered plate. The resulting sintered plate was then cut into a <NUM> by <NUM> by a laser process to produce a positive electrode plate.

The results of Examples <NUM> to <NUM> are shown in Tables 1A and 1B.

Claim 1:
An all-solid lithium battery comprising:
an oriented positive electrode plate that is a lithium complex oxide sintered plate having a porosity of <NUM> to <NUM>%, wherein the porosity is determined as described in the description and wherein the lithium complex oxide sintered plate contains a plurality of primary grains composed of lithium complex oxide having a layered rock salt structure, and the primary grains are oriented at a mean orientation angle of more than <NUM>° to <NUM>° to a main face of the oriented positive electrode plate, wherein the orientation angle is a tilt angle of the (<NUM>) plane of each primary grain to a main face of the oriented positive electrode plate determined as described in the description;
a negative electrode plate containing Ti and capable of intercalating and deintercalating lithium ions at <NUM> V or higher (vs. Li/Li+); and
a solid electrolyte having a melting point lower than a melting point or decomposition temperature of the oriented positive electrode plate and the negative electrode plate, wherein at least <NUM>% of pores in the oriented positive electrode plate is filled with the solid electrolyte in an observation of a cross-section perpendicular to a main face of the oriented positive electrode plate,
(i) wherein the solid electrolyte is represented by a formula xLiOH·yLi<NUM>SO<NUM> where x+y=<NUM>, and <NUM>≤x≤<NUM> or
(ii) wherein the solid electrolyte is represented by a formula Lia(OH)bFcBr where <NUM>≤a≤<NUM>, b=a-c-<NUM>, and <NUM>≤c≤<NUM> and comprises an antiperovskite crystal phase.