Nanosheets of Ca.sup.2+ and Y.sup.3+, with CO.sub.3.sup.2− in the interlayer with a uniform diameter and lengths of several tens of microns have been successfully synthesized in a hydrotalcite layer structure (a layered double hydroxide), using a hydrothermal method. The formation mechanism of lamellar CaY—CO.sub.3.sup.2− layered double hydroxides (LDHs) depends on the molar ratio of Ca and Y and the reaction time and temperature. The resulting LDH materials exhibit excellent affinity and selectivity for heavy transition metal and metalloid ions.

A method for preparing a composition including mineral particles functionalized by at least one organic group and having a specific surface defined according to the BET method greater than 500 m.sup.2/g, involves: —choosing a phyllosilicate composition, including mineral particles having a thickness of less than 100 nm, a largest dimension of less than 10 μm and belonging to the family of lamellar silicates; —choosing at least one functionalizing agent, from the group formed from the oxysilanes and oxygermanes having at least one organic group, —bringing the phyllosilicate composition into contact with a functionalizing solution including the functionalizing agent, so as to obtain a phyllosilicate composition including mineral particles functionalized by the organic group, while choosing the organic group from the group formed from the cationic heteroaryl groups, the quaternary ammonium groups and the salts of same. The phyllosilicate composition obtained by the method is also described.

A lithium-manganese composite oxide represented by formula (1): Li.sub.1+x[(Fe.sub.yNi.sub.1−y).sub.zMn.sub.1−z].sub.1−xO.sub.2 (1) wherein x, y, and z satisfy the following: 0<x≤⅓, 0≤y<1.0, and 0<z≤0.6, and wherein the content ratio of Li to the total content of Fe, Ni, and Mn (Li/(Fe+Ni+Mn)) is 1.55 or less on a molar ratio basis, the lithium-manganese composite oxide containing a crystalline phase having a layered rock-salt structure. This composite oxide is a novel material made from less resource-constrained and cheaper elements, and exhibits a high specific capacity, excellent charge-and-discharge cycle characteristics, and a high discharge capacity at a high current density (excellent rate characteristics), when used in the positive electrode material for lithium-ion secondary batteries.

Electrode materials for electrochemical cells and batteries and methods of producing such materials are disclosed herein. The electrode materials comprise an active lithium metal oxide material prepared by: (a) contacting the lithium metal oxide material with an aqueous acidic solution containing one or more metal cations; and (b) heating the so-contacted lithium metal oxide from step (a) to dryness at a temperature below 200° C. The metal cations in the aqueous acidic solution comprise one or more metal cations selected from the group consisting of an alkaline earth metal ion, a transition metal ion, and a main group metal ion.

Described is a method for extracting lithium from salt lake brine and simultaneously preparing aluminum hydroxide. This method includes a. adding an aluminum salt to the brine, adding an alkali solution, then subjecting to crystallization reaction and solid-liquid separation to obtain lithium-containing brine; b. evaporating and concentrating the lithium-containing brine, adding an aluminum salt, adding an alkali solution dropwise to perform a co-precipitation reaction and solid-liquid separation to obtain a lithium-containing layered material filter cake, wherein in steps a and b, the alkali solution is an alkali solution free of carbonate ion; c. dispersing the lithium-containing layered material filter cake in deionized water to form a suspension slurry, then adjusting the pH value of the suspension slurry so as to carry out a lithium deintercalation reaction; d. filtering to obtain aluminum hydroxide filter cake; e. washing the aluminum hydroxide filter cake with deionized water and drying.

This lithium transition metal composite oxide, which configures a secondary battery positive electrode active material, is a composite oxide represented by general formula Li.sub.α[Li.sub.xMn.sub.yCo.sub.zMe(.sub.1-x-y-z)]O.sub.2 (in the formula, Me is at least one species selected from Ni, Fe, Ti, Bi and Nb, and 0.5<α<1, 0.05<x<0.25, 0.4<y<0.7, and 0<z<0.25), and has at least one crystal structure selected from the O2 structure, the T2 structure and the O6 structure. The ratio (Co2/Co1) of the Co molar fraction (Co2) in the surface of the oxide to the Co molar fraction (Co1) in the entire lithium transition metal composite oxide is 1.2<(Co2/Co1)<6.0.

A hybrid functionalized lamellar comprises a layered double hydroxide and [Sn.sub.2S.sub.6].sup.4− anions intercalated with the gallery of the layered double hydroxide to form a [Sn.sub.2S.sub.6].sup.4− intercalated layered double hydroxide.

A method of preparing a positive electrode active material for a secondary battery includes preparing a positive electrode active material precursor containing 60 mol % or more of nickel (Ni) among total metals, mixing the positive electrode active material precursor and a lithium raw material source and performing primary pre-sintering in an oxidizing atmosphere to form a pre-sintered product, and performing secondary main sintering on the pre-sintered product in an air atmosphere to form a lithium transition metal oxide.

Provided is an active material for a fluoride-ion secondary battery, the active material containing a composite fluoride. The composite fluoride has a layered structure and is represented by a composition formula A.sub.mM.sub.nF.sub.x, where A is an alkali metal, M is a transition metal, 0<m≤2, 1≤n≤2, and 3≤x≤4. The alkali metal may be at least one kind selected from the group consisting of Na, K, Rb, and Cs. The transition metal may be a 3d transition metal.

A method for preparing an anion adsorbent may be provided, which comprises the steps of: mixing at least two metal salts with each other, thereby forming a stack structure in which cationic compound layers and anionic compound layers containing anions and water of crystallization are alternately stacked on one another; performing a first heat treatment on the stack structure to expand between the cationic compound layers, thereby preparing a preliminary anion adsorbent; and performing a second heat treatment on the preliminary anion adsorbent to remove the anions and the water of crystallization from the anionic compound layers while allowing at least one of the anions to remain, thereby preparing the anion adsorbent.