Disclosed are a silicon-carbon composite material for a secondary lithium battery and a preparation method therefor. The silicon-carbon composite material for a secondary lithium battery comprises a core containing a silicon-based material, a first coating layer, and a second coating layer. The first coating layer is an electrically conductive layer, the second coating layer is an ion-conducting layer, and the first coating layer and the second coating layer are not limited to a certain order. In the silicon-carbon composite material provided by the present disclosure, the coating layer is a composite material, which combines the electroconductive (or ion-conducting) capability of a matrix material, and the reinforcing and toughening properties of a reinforcing phase, such that the material has a strong anti-expansion capability. In the secondary battery, the coating layer is less prone to breaking, which results in less fresh surface and so reduces the consumption of an electrolyte and improves the cycle performance of the battery. Additionally, the preparation method of the present disclosure is simple and easy to implement, and is suitable for large-scale industrial production.

The present invention provides a positive-electrode active material for a lithium-ion secondary cell or a sodium-ion secondary cell, which can effectively exhibit more excellent charge/discharge characteristics; and a method for manufacturing the positive-electrode active material. Namely, the present invention relates to a positive-electrode active material for a secondary cell comprising an oxide represented by formula (A): LiFe.sub.aMn.sub.bM.sub.cPO.sub.4, formula (B): LiFe.sub.aMn.sub.bM.sub.cSiO.sub.4, or formula (C): NaFe.sub.gMn.sub.hQ.sub.iPO.sub.4; and carbon derived from a cellulose nanofiber supported thereon.

The present invention provides a positive-electrode active material for a lithium-ion secondary cell or a sodium-ion secondary cell, which can effectively exhibit more excellent charge/discharge characteristics; and a method for manufacturing the positive-electrode active material. Namely, the present invention relates to a positive-electrode active material for a secondary cell comprising an oxide represented by formula (A): LiFe.sub.aMn.sub.bM.sub.cPO.sub.4, formula (B): LiFe.sub.aMn.sub.bM.sub.cSiO.sub.4, or formula (C): NaFe.sub.gMn.sub.hQ.sub.iPO.sub.4; and carbon derived from a cellulose nanofiber supported thereon.

A negative electrode material mixture with a negative electrode active material including a Si-containing material and a carbon material; and a carbon nanotube. The Si-containing material includes, a first composite material in which Si particles are dispersed in a lithium silicate phase and/or a carbon phase, and a second composite material in which Si particles are dispersed in a SiO.sub.2 phase, at least the first composite material. A mass ratio X of the first composite material to a total of the first and second composite materials, and a mass ratio Y of the total of the first second composite materials to a total of the first composite material, the second composite material, and the carbon material satisfy a relational expression (1): 100Y−32.2X.sup.5+65.479X.sup.4−55.832X.sup.3+18.116X.sup.2−6.9275X−3.5356<0, X≤1, and 0.06≤Y. The non-aqueous electrolyte includes LiPF.sub.6 and LiN(SO.sub.2F).sub.2.

Embodiments of the present disclosure are directed to embodiments of synthetic functionalized additives. The synthetic functionalized additive may include a layered magnesium silicate. The layered magnesium silicate may include a first functionalized silicate layer including a first tetrahedral silicate layer covalently bonded to at least two different functional groups, an octahedral brucite layer, including magnesium, and a second functionalized silicate layer including a second tetrahedral silicate layer covalently bonded to at least two different functional groups. The octahedral brucite layer may be positioned between the first functionalized silicate layer and the second functionalized silicate layer. The at least two different functional groups covalently bonded to the first tetrahedral silicate layer may be the same or different than the at least two different functional groups covalently bonded to the second tetrahedral silicate layer.

The present invention refers to a stable sodium and iron silicate solution that has a weight ratio of SiO.sub.2 to Na.sub.2O from 1.5 to 2.5 and a total percentage of solids, expressed by the sum of SiO.sub.2 and Na.sub.2O, from 20% to 55%. Said solution also has a soluble iron content, expressed by Fe, from 0.1% to 7%, and a water content from 38% to 79.9%. The present invention also refers to the process for preparing said stable solution of sodium and iron silicate, which comprises the steps of: (a) providing a siliceous material containing iron; (b) submitting said siliceous material containing iron to a hydrothermal treatment with caustic soda under high temperature and controlled pressure; and (c) filtering said reacted solution to separate the reacted portion of the hydrothermal treatment from the unreacted portion. Additionally, the present invention refers to the uses of said stable sodium and iron silicate solution.

A solid conductor including: a compound represented by Formula 1, a compound represented by Formula 2, or a combination thereof
Li.sub.1+x+y−zTa.sub.2−xM.sub.xP.sub.1−yQ.sub.yO.sub.8−zX.sub.z  Formula 1
wherein, in Formula 1, M is an element having an oxidation number of +4, Q is an element having an oxidation number of +4, X is a halogen, a pseudohalogen, or a combination thereof, and 0≤x≤2, 0≤y<1, and 0≤z≤2, except that cases i) x and y and z are simultaneously 0, ii) M is Hf, X is F, x is 1, y is 0, and z is 1, iii) M is Hf, X is Cl, x is 2, y is 0, and z is 2, and iv) M is Hf, X is F, x is 2, y is 0, and z is 2,
Li.sub.1+x+y−zTa.sub.2−xM.sub.xP.sub.1−yQ.sub.yO.sub.8.Math.zLiX  Formula 2
wherein, in Formula 2, M is an element having an oxidation number of +4, Q is an element having an oxidation number of +4, X is a halogen, a pseudohalogen, or a combination thereof, and 0≤x≤2, 0≤y<1, and 0≤z2, except that cases i) x and y and z are simultaneously 0, ii) M is Hf, X is F, x is 1, y is 0, and z is 1, iii) M is Hf, X is Cl, x is 2, y is 0, and z is 2, and iv) M is Hf, X is F, x is 2, y is 0, and z is 2.

A solid conductor including: a compound represented by Formula 1, a compound represented by Formula 2, or a combination thereof
Li.sub.1+x+y−zTa.sub.2−xM.sub.xP.sub.1−yQ.sub.yO.sub.8−zX.sub.z  Formula 1
wherein, in Formula 1, M is an element having an oxidation number of +4, Q is an element having an oxidation number of +4, X is a halogen, a pseudohalogen, or a combination thereof, and 0≤x≤2, 0≤y<1, and 0≤z≤2, except that cases i) x and y and z are simultaneously 0, ii) M is Hf, X is F, x is 1, y is 0, and z is 1, iii) M is Hf, X is Cl, x is 2, y is 0, and z is 2, and iv) M is Hf, X is F, x is 2, y is 0, and z is 2,
Li.sub.1+x+y−zTa.sub.2−xM.sub.xP.sub.1−yQ.sub.yO.sub.8.Math.zLiX  Formula 2
wherein, in Formula 2, M is an element having an oxidation number of +4, Q is an element having an oxidation number of +4, X is a halogen, a pseudohalogen, or a combination thereof, and 0≤x≤2, 0≤y<1, and 0≤z2, except that cases i) x and y and z are simultaneously 0, ii) M is Hf, X is F, x is 1, y is 0, and z is 1, iii) M is Hf, X is Cl, x is 2, y is 0, and z is 2, and iv) M is Hf, X is F, x is 2, y is 0, and z is 2.

A negative electrode active material includes: particles of negative electrode active material, the particles of negative electrode active material contain particles of silicon compound containing a silicon compound (SiO.sub.x:0.5≤x≤1.6); the particles of silicon compound contain at least one kind or more of Li.sub.2SiO.sub.3 and Li.sub.4SiO.sub.4; the particles of negative electrode active material contain Li.sub.2CO.sub.3 and LiOH on a surface thereof; and a content of the Li.sub.2CO.sub.3 is 0.01% by mass or more and 5.00% by mass or less relative to a mass of the particles of negative electrode active material and a content of the LiOH is 0.01% by mass or more and 5.00% by mass or less relative to the mass of the particles of negative electrode active material. Thus a negative electrode active material is capable of improving initial charge/discharge characteristics and the cycle characteristics when used as a negative electrode active material of the secondary battery.

A method for the alkaline digestion of soda-lime glass comprising forming a mixture of soda lime glass and a hydroxide solution, the mixture having at least 100 grams of glass per litre of H2O, the hydroxide solution having a concentration of 1M or greater to thereby form an aqueous sodium silicate fraction having a silicate concentration of 50 g/L or greater (calculated as SiO2 equivalent) and a ratio of SiO2:M2O of at least 1, wherein M2O is an alkaline metal oxide, by digesting the glass in the mixture; and separating the aqueous sodium silicate fraction from solids. The solids contain calcium silicate hydrate and undissolved glass. The calcium silicate hydrate can be CSH treated with an acid to thereby dissolve soluble metals from the CSH and separating a liquid phase from a solid phase, the solid phase comprising SiO2 or silica gel.