Patent ID: 8753775

Claim:
A lithium secondary battery comprising: a positive electrode comprising a positive active material; a negative electrode comprising a negative active material; and an electrolyte, and the electrolyte comprises a solvent, a polyether modified silicone oil where a linear polyether chain is linked to a polysiloxane chain, and a solute comprising a lithium salt, the negative active material comprises a multi-phase alloy powder comprising a multi-phase alloy powder particle which comprises Si-phase and SiM-phase, and also comprises either one or both of X-phase or SiX-phase, and an amount of Si-phase on a surface of the multi-phase alloy powder particle is less than that inside of the particle, wherein M is at least one element selected from the group consisting of Ni, Co, As, B, Cr, Cu, Fe, Mg, Mn, and Y, X is at least one element selected from the group consisting of Ag, Cu, and Au, M and X are not both Cu, and each Si-phase, SiM-phase, X-phase and SiX-phase is present in a uniformly mixed state except on the surface of the multi-phase alloy powder particle.