According to one approach, an electrode composite (10) is provided. The electrode composite (10) includes a negative electrode active material-containing layer (3b) and an insulating particle layer (4). The negative electrode active material-containing layer (3b) includes negative electrode active material secondary particles (3A) having an average secondary particle size of from 1 µm to 30 µm. The insulating particle layer (4) is provided on the negative electrode active material-containing layer (3b). The insulating particle layer (4) includes a first surface (4-1) and a second surface (4-2) opposed to the first surface (4-1). The first surface (4-1) is in contact with the negative electrode active material-containing layer (3b). The second surface (4-2) has a surface roughness of 0.1 µm or less.