Patent ID: 7794878

Claim:
A negative electrode for a lithium secondary battery, comprising a sheet-like current collector and an active material layer being carried on said current collector and including a silicon atom, wherein said active material layer comprises a plurality of columnar particles, each of said columnar particles is grown to tilt in one direction with respect to a direction normal to said current collector, and in a thickness direction of said active material layer, porosity Pc of a current collector side lower half of said active material layer and porosity Ps of a surface side upper half of said active material layer satisfy the relation, Pc<Ps, wherein the porosity Pc is an areal ratio of a void portion present at a lower half relative to the total area of said lower half and porosity Ps is an areal ratio of a void portion present at an upper half relative to the total area of said upper half, in a cross-section of said active material layer, an angle θ between a growth direction of said columnar particles and said direction normal to said current collector is increasing from a current collector-side to an active material layer surface-side, and a maximum angle θs and a minimum value θc of said angle θ satisfy the relation below: 10 °≦θs−θc, 0 °≦θc< 80°, and 10 °≦θs< 90°.