An oxide includes 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 5+ or 6+, Q is an element having an oxidation number of 4+, X is a halogen atom, a pseudohalogen, or a combination thereof,
0≤x<0.6, 0≤y<1, and 0≤z<1, wherein x and y are not 0 at the same time,
Li.sub.1−x+yTa.sub.2−xM.sub.xP.sub.1−yQ.sub.yO.sub.8.zLiX  Formula 2
wherein, in Formula 2, M is an element having an oxidation number of 5+ or 6+, Q is an element having an oxidation number of 4+, X is a halogen atom, a pseudohalogen or a combination thereof, 0≤x<0.6, 0≤y<1, and 0≤z<1, wherein x and y are not 0 at the same time, and
wherein in Formulas 1 and 2, M, Q, x, y, and z are independently selected.

An oxide includes 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 5+ or 6+, Q is an element having an oxidation number of 4+, X is a halogen atom, a pseudohalogen, or a combination thereof,
0≤x<0.6, 0≤y<1, and 0≤z<1, wherein x and y are not 0 at the same time,
Li.sub.1−x+yTa.sub.2−xM.sub.xP.sub.1−yQ.sub.yO.sub.8.zLiX  Formula 2
wherein, in Formula 2, M is an element having an oxidation number of 5+ or 6+, Q is an element having an oxidation number of 4+, X is a halogen atom, a pseudohalogen or a combination thereof, 0≤x<0.6, 0≤y<1, and 0≤z<1, wherein x and y are not 0 at the same time, and
wherein in Formulas 1 and 2, M, Q, x, y, and z are independently selected.

A negative electrode active material tor a secondary battery includes a silicate composite particle including crystalline silicon particles, an amorphous phase comprising an Li element, an O element, and an Si element, and a silicon oxide phase, wherein the silicon oxide phase and the silicon particles are dispersed in the amorphous phase.

A negative electrode active material tor a secondary battery includes a silicate composite particle including crystalline silicon particles, an amorphous phase comprising an Li element, an O element, and an Si element, and a silicon oxide phase, wherein the silicon oxide phase and the silicon particles are dispersed in the amorphous phase.

This application provides a silicon-based material, a preparation method thereof, and a secondary battery, a battery module, a battery pack, and an apparatus associated therewith. The silicon-based material includes a core structure and a coating layer provided on at least partial surface of the core structure, where the core structure includes both a silicon phase and a lithium metasilicate phase, and a particle size P of the lithium metasilicate phase is ≥30 nm. The silicon-based material of this application can not only increase energy density of a secondary battery with the silicon phase, but also improve structural stability and chemical stability of the silicon-based material, so that the secondary battery can deliver satisfactory and balanced cycling performance and first-cycle coulombic efficiency in overall.

A negative electrode active material for a secondary battery comprising silicate composite particles including silicon particles and a lithium silicate phase. The silicon particles are dispersed in the lithium silicate phase, the silicate composite particles have a porosity of 2% or less. In a diffraction pattern by X-ray diffraction (XRD), a ratio I.sub.2/I.sub.1 is 0.3 or less, the ratio I.sub.2/I.sub.1 being a ratio of an integrated intensity I.sub.2 of a peak derived from the lithium silicate phase that appears in a range of 2θ of 23° to 25° relative to an integrated intensity I.sub.1 of a peak derived from Si(111) plane of the silicon particles that appears in a range of 2θ of 27° to 30°.

Methods of making a negative electrode material for an electrochemical cell that cycles lithium ions is provided. The method may include centrifugally distributing a molten precursor comprising silicon, oxygen, and lithium by contacting the molten precursor with a rotating surface in a centrifugal atomizing reactor. The molten precursor is formed by combining lithium, silicon, and oxygen. For example, the precursor may be formed from a mixture comprising silicon dioxide (SiO.sub.2), lithium oxide (Li.sub.2O), and silicon (Si). The method may further include solidifying the molten precursor to form a plurality of substantially round solid electroactive particles comprising a mixture of lithium silicide (Li.sub.ySi, where 0<y≤4.4) and a lithium silicate (Li.sub.4SiO.sub.4) and having a D50 diameter of less than or equal to about 20 micrometers.

Methods of making a negative electrode material for an electrochemical cell that cycles lithium ions is provided. The method may include centrifugally distributing a molten precursor comprising silicon, oxygen, and lithium by contacting the molten precursor with a rotating surface in a centrifugal atomizing reactor. The molten precursor is formed by combining lithium, silicon, and oxygen. For example, the precursor may be formed from a mixture comprising silicon dioxide (SiO.sub.2), lithium oxide (Li.sub.2O), and silicon (Si). The method may further include solidifying the molten precursor to form a plurality of substantially round solid electroactive particles comprising a mixture of lithium silicide (Li.sub.ySi, where 0<y≤4.4) and a lithium silicate (Li.sub.4SiO.sub.4) and having a D50 diameter of less than or equal to about 20 micrometers.

A positive-electrode active material contains a lithium composite oxide containing manganese. The crystal structure of the lithium composite oxide belongs to a space group Fd-3m. The integrated intensity ratio I.sub.(111)/I.sub.(400) of a first peak I.sub.(111) on the (111) plane to a second peak I.sub.(400) on the (400) plane in an XRD pattern of the lithium composite oxide satisfies 0.05≤I.sub.(111)/I.sub.(400)≤0.90.

A negative electrode active material including a core containing SiO.sub.x (0≤x<2) and a lithium-containing compound, and a shell disposed on the core and containing SiO.sub.x (0≤x<2) and magnesium silicate.