Characterization of Sputter‐Deposited LiMn2 O 4 Thin Films for Rechargeable Microbatteries

Thin films of LiMn[sub 2]O[sub 4] spinel were fabricated by RF magnetron sputtering. The as-deposited films were amorphous but could be crystallized into a spinel structure by rapid thermal annealing in an oxygen atmosphere. The electrochemical performance of 2000 [angstrom] thick LiMn[sub 2]O[sub 4] thin-film cathodes were tested in a LiMn[sub 2]O[sub 4]/1M LiClO[sub 4] in PC + DME/Li cell. LiMn[sub 2]O[sub 4] spinel films prepared at 750 C showed good intercalation kinetics and very promising cycling behavior. Room temperature cycling of these films had capacities of about 50 [mu]Ah/cm[sup 2]-[mu]m at 200 [mu]A/cm[sup 2] and maintained more than 98% of their original capacity after more than 1000 cycles.