A graphite anode material, an anode, a lithium ion battery and preparation methods thereof. The graphite anode material includes a natural graphite core, a carbon coating layer, and a graphitizing filler. The natural graphite core has pores. The graphitizing filler is filled in the pores inside the natural graphite core. The graphitizing filler further forms the carbon coating layer. The preparation method includes: mixing natural graphite with a filler, and then pulverizing to obtain a graphite powder body; and graphitizing the graphite powder body in a protective atmosphere to obtain a graphite anode material. The preparation method reduces material turnover and residual loss, and achieves simple process and high production efficiency. The anode and lithium ion battery prepared have high first efficiency and excellent cycling performance.

The present invention relates to an anode active material, a nonaqueous lithium secondary battery comprising the same, and a preparation method therefor, and the purpose of the present invention is to improve high-rate charging characteristics without deterioration of charging and discharging efficiency and lifetime characteristics when applying an amorphous carbon coating layer as the anode active material of the nonaqueous lithium secondary battery, wherein the amorphous carbon coating layer comprising MoPx particles composed of MoP and MoP.sub.2 is formed on the surface of a carbon-based material, thereby reducing resistance when intercalating lithium ions into the surface of the carbon-based material, and improving reactivity and structural stability of the surface. The anode active material according to the present invention comprises a carbon-based material, and an amorphous carbon coating layer comprising MoPx particles composed of MoP and MoP.sub.2 formed on the surface of the carbon-based material.

A positive electrode active material having a core/shell structure, which includes a sulfur-carbon composite containing thermally expanded-reduced graphene oxide, a carbon material as a core, and carbon nanotubes as a shell. A method for preparing a positive electrode active material having a core/shell structure for a lithium secondary battery, including the steps of thermally expanding graphene oxide by heat treatment at a temperature in a range of 300° C. to 500° C. to prepare a thermally-expanded graphene oxide. Then, reducing the thermally-expanded graphene oxide by heat treatment at a temperature in a range of 700° C. to 1200° C. to prepare a thermally expanded-reduced graphene oxide. Next, mixing the thermally expanded-reduced graphene oxide and sulfur to prepare a sulfur-carbon composite. Last, mixing the sulfur-carbon composite and carbon nanotubes to form carbon nanotubes on a surface of the sulfur-carbon composite.

A coated positive electrode active material according to the present disclosure includes a positive electrode active material and a coating layer coating at least partially a surface of the positive electrode active material. The coating layer includes Li, Zr, and F. A material of the coating layer may be represented, for example, by composition formula (1) Li.sub.αZr.sub.βF.sub.γ . . . Formula (1). In the composition formula (1), the symbols α, β, and γ satisfy 0<α<8, 0<β≤1.1, and 0<γ≤8. A positive electrode material of the present disclosure includes the coated positive electrode active material and a first solid electrolyte. A battery of the present disclosure includes a positive electrode including the positive electrode material, a negative electrode, and an electrolyte layer provided between the positive electrode and the negative electrode.

A cathode active material for a lithium secondary battery includes a core portion comprising a lithium metal oxide particle, and a coating layer at least partially covering a surface of the core portion and including a lithium boron composite oxide. The lithium boron composite oxide is included in an amount from 100 ppm to 1,500 ppm based on a total weight of the cathode active material. A lithium secondary battery having improved structural stability and electrical property is provided using the cathode active material.

A method can include milling a plurality of silicon particles to form a plurality of milled silicon particles. The milled silicon particles can optionally include collecting the milled silicon particles, powdering the milled silicon particles, and milling the milled silicon particles a second time.

A spheronized carbonaceous negative electrode active material and a method of preparing a spheronized carbonaceous negative electrode active material, which has an average particle diameter (D.sub.50) of 8.5-10.5 μm, a minimum particle diameter (D.sub.min) of 2.3 μm or more, and a tap density of 1.00-1.20 g/cc.

Methods for making nanocomposites are provided. In an embodiment, such a method comprises combining a first type of nanostructure with a bulk material in water or an aqueous solution, the first type of nanostructure functionalized with a functional group capable of undergoing van der Waals interactions with the bulk material, whereby the first type of nanostructure induces exfoliation of the bulk material to provide a second, different type of nanostructure while inducing association between the first and second types of nanostructures to form the nanocomposite.

A positive electrode active material for obtaining a lithium ion secondary battery, wherein capacity, electron conductivity, durability, and heat stability at the time of overcharge are improved, durability and heat stability being achieved at a high level, and including: a lithium nickel manganese composite oxide composed of secondary particles, in which a plurality of primary particles are flocculated, wherein the composite oxide is represented by a general formula (1): Li.sub.dNi.sub.1-a-b-cMn.sub.aM.sub.bTi.sub.cO.sub.2 (wherein, M is at least one kind of element selected from Co, W, Mo, V, Mg, Ca, Al, Cr, Zr and Ta, 0.05≤a≤0.60, 0≤b≤0.60, 0.02≤c≤0.08, 0.95≤d≤1.20), at least a part of titanium in the composite oxide is solid-solved in the primary particles, and, a lithium titanium compound exists on a surface of the positive electrode active material for the lithium ion secondary battery.

A silicon material can include a silicon aggregate comprising a plurality of porous silicon nanoparticles welded together. The silicon aggregate can optionally have a polyhedral morphology. A method can include: receiving a plurality of porous silicon nanoparticles and cold welding the plurality of porous silicon nanoparticles into an aggregated silicon particle.