Abstract: Disclosed is a fuel cell system wherein the flow of fuel and oxygen is optimized thereby improving the thermal efficiency of the entire system. The fuel cell system comprises at least one stack for generating electrical energy by an electrochemical reaction between hydrogen gas and oxygen, a fuel supply portion for supplying fuel to the stack, and an oxygen supply portion for supplying oxygen to the stack. The stack is formed in a stacked configuration with MEAs and separators. The separators are positioned on either surface of the MEAs. The separators have a plurality of ribs proximate to the MEAs which define a plurality of channels wherein the ratio of a width of the channels to the width of the ribs is from about 0.8 to 1.5.

Abstract: A method for preparing a positive active material for a rechargeable lithium battery is provided. In this method, a lithium source, a metal source, and a doping liquid including a doping element are mixed and the mixture is heat-treated.

Abstract: Disclosed is a lithium secondary battery including a positive electrode comprising a combination of positive active materials. The combination includes a material represented by one or both of Formulae 1 and 2; and a material of Formula 3 as follows: LiaNibMncMdO2 ??(Formula 1) where 0.90?a?1.2; 0.5?b?0.9; 0<c<0.4; 0?d?0.2; LiaNibCocMndMeO2 ??(Formula 2) where 0.90?a?1.2, 0.5?b?0.9, 0<c<0.4, 0<d<0.4, and 0?e?0.2; LiaCoMbO2 ??(Formula 3) where 0.90?a?1.2 and 0?b?0.2; and each M of Formulae 1-3 is independently selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl, Si, Ge, Sn, P, As, Sb, Bi, S, Se, Te, Po, and combinations.

Abstract: A fuel cell system optimizing the ratio of width of a channel to a width of a rib forming a passage for supplying fuel and air, the ratio of width thereof to a height of a channel, and the number of passages, thereby improving the fuel diffusing performance and reducing a pressure drop therein is provided. The fuel cell system includes at least one stack for generating electrical energy by an electrochemical reaction between hydrogen and oxygen, a fuel supply portion for supplying fuel to the stack, and an oxygen supply portion for supplying oxygen to the stack. The stack is formed into a stacked configuration having a plurality of membrane electrode assemblies separated by separators. The separators have ribs which closely contact the adjacent membrane electrode assemblies and form channels through which the oxygen and hydrogen flow. The ratio of the width of a channel to the height of the same is between about 0.6 and about 0.8.

Abstract: A fuel cell system includes a fuel supply unit for supplying fuel, an air supply unit for supplying air, and a stack for generating electric energy through an electro-chemical reaction between hydrogen supplied from the fuel supply unit and oxygen supplied from the air supply unit. The stack includes a membrane-electrode assembly and separators disposed on both sides of the membrane-electrode assembly. Each of the separators has a pathway for transferring the air or the hydrogen, and a ratio of the width to the depth of the pathway is within a range from 0.7 to 1.3.

Abstract: Provided is a positive electrode for a lithium secondary battery including a positive active material and a conductive agent comprising a plurality of plate-structured carbon particles.

Abstract: Disclosed is a method of preparing a positive active material for a rechargeable lithium battery including adding first and second compounds to a solvent to prepare an acidic solution with a pH from 0.

Abstract: A positive active material for a rechargeable lithium-sulfur battery includes a core of a sulfur compound and a surface-passivation layer formed on the core. The surface-passivation layer is made of a coating-element-included compound selected from the group consisting of a coating-element-included hydroxide, a coating-element-included oxyhydroxide, a coating-element-included oxycarbonate, a coating-element-included hydroxycarbonate, a mixture thereof.

Abstract: A positive electrode for a rechargeable lithium battery of preparing the same. The positive electrode includes a current collector, a positive active material layer coated on the current collector, and a surface-treatment layer. The positive active material layer includes a positive active material. The surface-treatment layer includes a compound selected from the group consisting of a coating-element-included hydroxide, a coating-element-included oxyhydroxide, a coating-element-included oxycarbonate, a coating-element-included hydroxycarbonate, and a mixture thereof. The positive electrode is prepared by coating a current collector with a positive active material composition to form a positive active material layer, and treating the current collector coated with the positive active material layer with a coating liquid, and drying the treated current collector. The coating liquid includes a coating element or coating-element-included compound.

Abstract: A positive active material for a rechargeable lithium-sulfur battery includes a core of a sulfur compound and a surface-passivation layer formed on the core. The surface-passivation layer is made of a coating-element-included compound selected from the group consisting of a coating-element-included hydroxide, a coating-element-included oxyhydroxide, a coating-element-included oxycarbonate, a coating-element-included hydroxycarbonate, a mixture thereof.

Abstract: A positive active material includes a core including a lithiated compound, and at least two surface-treatment layers formed on the core. The surface-treatment layer includes at least one compound selected from the group consisting of a coating-element-included hydroxide, a coating-element-included oxyhydroxide, a coating-element-included oxycarbonate, and a coating-element-included hydroxycarbonate. The coating element is selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, and As.

Abstract: Provided are a positive active material and a method of preparing for the same. The positive active material comprises a core and a surface-treatment layer on the core. The core includes at least one lithiated compound, and the surface-treatment layer includes at least one coating element-included oxide. The lithiated compound includes a secondary particle of which average particle size is larger than or equal to 1 &mgr;m and less than 10 &mgr;m. The secondary particle is formed of an agglomeration of small primary particles of an average size of 1 to 3 &mgr;m in diameter. The positive active material is prepared by coating the lithiated compound with an organic solution or an aqueous solution including a coating-element source and heat-treating the coated compound.

Abstract: A process of manufacturing a positive active material for a lithium secondary battery includes adding a metal source to a doping element-containing coating liquid to surface-treat the metal source, wherein the metal source is selected from the group consisting of cobalt, manganese, nickel, and combination thereof; drying the surface-treated metal source material to prepare a positive active material precursor; mixing the positive active material precursor with a lithium source; and subjecting the mixture to heat-treatment. Alternatively, the above drying step during preparation of the positive active material precursor is substituted by preheat-treatment or drying followed by preheat-treatment.

Abstract: Disclosed is a positive active material for a rechargeable lithium battery, including a lithiated intercalation compound and an additive compound. The additive compound comprises one or more intercalation element-included oxides which have a charging voltage of 4.0 to 4.6V when 5-50% of total intercalation elements of the one or more intercalation element-included oxides are released during charging.

Abstract: Disclosed is a negative active material for a lithium rechargeable battery comprising a core having a carbon source with a surface-treatment layer formed on the surface of the core. The surface-treatment layer has at least one amorphous, semi crystalline, or crystalline coating element compound selected from the group consisting of coating-element-included hydroxides, coating-element-included oxyhydroxides, coating-element-included-oxycarbonates, and coating-element-included hydroxidecarbonates. Also disclosed is a method of preparing a negative active material for a lithium rechargeable battery comprising coating a carbon source with a coating liquid, and drying the carbon source. The coating liquid comprises a solute of a coating element source and a solvent of a mixture of an organic solvent and water.

Abstract: A positive active material for a rechargeable lithium-sulfur battery includes a core of a sulfur compound and a surface-passivation layer formed on the core. The surface-passivation layer is made of a coating-element-included compound selected from the group consisting of a coating-element-included hydroxide, a coating-element-included oxyhydroxide, a coating-element-included oxycarbonate, a coating-element-included hydroxycarbonate, a mixture thereof.

Abstract: A process of manufacturing a positive active material for a lithium secondary battery includes preparing a coating-element-containing organic suspension by adding a coating-element source to an organic solvent, adding water to the suspension to prepare a coating liquid, coating a positive active material with the coating liquid, and drying the coated positive active material.

Abstract: An active material for a battery has a surface treatment layer that includes a conductive agent and at least one coating-element-containing compound selected from the group consisting of a coating-element-containing hydroxide, a coating-element-containing oxyhydroxide, a coating-element-containing oxycarbonate, a coating-element-containing hydroxycarbonate, and a mixture thereof.

Abstract: A positive electrode for a rechargeable lithium battery of preparing the same. The positive electrode includes a current collector, a positive active material layer coated on the current collector, and a surface-treatment layer. The positive active material layer includes a positive active material. The surface-treatment layer includes a compound selected from the group consisting of a coating-element-included hydroxide, a coating-element-included oxyhydroxide, a coating-element-included oxycarbonate, a coating-element-included hydroxycarbonate, and a mixture thereof. The positive electrode is prepared by coating a current collector with a positive active material composition to form a positive active material layer, and treating the current collector coated with the positive active material layer with a coating liquid, and drying the treated current collector. The coating liquid includes a coating element or coating-element-included compound.

Abstract: A method for preparing a positive active material for a rechargeable lithium battery is provided. In this method, a lithium source, a metal source, and a doping liquid including a doping element are mixed and the mixture is heat-treated.