An electrode for an electrochemical device is disclosed. The electrode comprises a lithium host material; and a porous coating on the lithium host material. The porous coating can comprise a solid-state ion conducting electrolyte material selected from: (i) lithium aluminum oxides, (ii) lithium containing phosphates, (iii) Li.sub.xPON wherein x is 1, 1.5, 3, or 6, (iv) Li.sub.xSiPON wherein x is 1, 1.5, 3, or 6, (v) Li.sub.xSiON wherein x is 2, 4, or 6, (vi) lithium lanthanum zirconium oxides, and (vii) mixtures of two or more of (i), (ii), (iii), (iv), (v), and (vi).

The porous coating comprising the solid-state ion conducting electrolyte material may be formed from one or more precursors that form the porous coating comprising the solid-state ion conducting electrolyte material upon cycling of the electrochemical device.

A proton conductor contains a metal oxide that has a perovskite structure and that is represented by formula (1): A.sub.xB.sub.1-yM.sub.yO.sub.3-δ, where an element A is at least one element selected from the group consisting of Ba, Ca, and Sr, an element B is at least one element selected from the group consisting of Ce and Zr, an element M is at least one element selected from the group consisting of Y, Yb, Er, Ho, Tm, Gd, In, and Sc, δ indicates an oxygen deficiency amount, and 0.95≤x≤1 and 0<y≤0.5 are satisfied.

Provided are a member for a sodium-ion secondary battery and a sodium-ion secondary battery both of which are not susceptible to deterioration of charge/discharge cycle characteristics due to charge and discharge. A member 8 for a sodium-ion secondary battery includes: a solid electrolyte layer 2 having sodium-ion conductivity; a metallic sodium layer 6 disposed on one principal surface 2b of the solid electrolyte layer 2 and made of metallic sodium; and a metallic layer 5 provided between the solid electrolyte layer 2 and the metallic sodium layer 6 and made of a metal different from the metallic sodium.

An all-solid secondary battery includes: a cathode layer including a cathode active material; an anode layer including an anode current collector, a first anode active material layer, and a second anode active material layer between the anode current collector and the first anode active material layer; and a solid electrolyte layer between the cathode layer and the anode layer and including a solid electrolyte, wherein the first anode active material layer is adjacent to the solid electrolyte layer, has pores, and contains a metal or metal alloy capable of forming an alloy or a compound with lithium, and the second anode active material layer includes a second anode active material including a carbon anode active material and optionally a metal or metalloid anode active material.

A sulfide-impregnated solid-state battery is provided. The battery comprises a cell core constructed by basic cell units. Each unit comprises a positive electrode comprising a cathode layer and a positive meshed current collector comprising a conductive material which is further coated by oxide-based solid-state electrolyte. The cell unit further comprises a negative electrode comprising an anode layer and a negative meshed current collector comprising a conductive material which is further coated by oxide-based solid-state electrolyte. The positive and negative electrodes are stacked together to form the cell unit. The two coated oxide-based solid electrolyte layers are disposed between the positive and negative electrode as dual separators. Such a cell unit may be repeated or connected in parallel or bipolar stacking to form the cell core to achieve a desired battery voltage, power and energy. The cell core comprises a sulfide-based solid-state electrolyte dispersed in the pore structures of cell core.

A method of preparing a lithium-ion conducting garnet via low-temperature solid-state synthesis is disclosed. The lithium-ion conducting garnet comprises a substantially phase pure aluminum-doped cubic lithium lanthanum zirconate (Li.sub.7La.sub.3Zr.sub.2O.sub.14). The method includes preparing nanoparticles comprising lanthanum zirconate (La.sub.2Zr.sub.2O.sub.7-np) via pyrolysis-mediated reaction of lanthanum nitrate (La(NO.sub.3).sub.3) and zirconium nitrate (Zr(NO.sub.3).sub.4). The method also includes pyrolyzing a solid-state mixture comprising the La.sub.2Zr.sub.2O.sub.7-np, lithium nitrate (LiNO.sub.3), and aluminum nitrate (Al(NO.sub.3).sub.3) to give the Li.sub.7La.sub.3Zr.sub.2O.sub.14 and thereby prepare the lithium-ion conducting garnet. A lithium-ion conducting garnet prepared via the method is also disclosed.

A solid oxide electrochemical device comprises a solid electrolyte layer, the first surface and second surface having surface pores formed therein; a first composite electrolyte layer composed of metal and a solid electrolyte and having a first porosity; a second composite electrolyte layer composed of metal and the solid electrolyte and having the first porosity, the solid electrolyte layer sandwiched between the first composite electrolyte layer and the second composite electrolyte layer; a cathode on one of the first composite electrolyte layer and the second composite electrolyte layer; and an anode on another of the first composite electrolyte layer and the second composite electrolyte layer. The anode comprises an anode metal layer comprising pores; anode active material; and reforming catalyst, wherein the anode active material and the reforming catalyst line walls of the pores in the anode metal layer.

Provided is a member for a power storage device that, even when the amount of electrode active material supported is increased, enables charge and discharge and thus achieves a high capacity. A member 6 for a power storage device includes: a solid electrolyte layer 1; and an electrode layer 2 provided on the solid electrolyte layer 1 and made of a sintered body of an electrode material layer 2A containing an electrode active material precursor powder having an average particle diameter of not less than 0.01 μm and less than 0.7 μm.

A positive electrode active material includes a lithium-transition metal composite phosphate including a first crystalline phase having a composition represented by Formula 1 and having an olivine structure, and a second crystalline phase having a composition represented by Formula 2 and having a pyrophosphate-containing structure, wherein the second crystalline phase is in an amount of greater than 0 mole percent and not greater than 50 mole percent with respect to a total number of moles of the first crystalline phase and the second crystalline phase, a positive electrode, a secondary battery:

Li.sub.xM1.sub.yPO.sub.4   Formula 1

Li.sub.aM2.sub.b(P.sub.2O.sub.7).sub.4   Formula 2 In Formulas 1 and 2, 0.9≤x≤1.1, 0.9≤y≤1.1, 5.5≤a≤6.5, and 4.8≤b≤5.2, and M1 and M2 are each independently an element from Groups 3 to 11 in the 4th period of the Periodic Table of the Elements, or a combination thereof.

An all-solid lithium ion secondary battery includes a pair of electrodes and a solid electrolyte provided between the pair of electrodes. At least one of the pair of electrodes includes an active-material layer and an intermediate layer. An active material constituting the active-material layer has a core-shell structure which has a core region and a shell region and a composition of the intermediate layer is intermediate between the solid electrolyte and the shell region.