Activating AlN thin film by introducing Co nanoparticles as a new anode material for thin-film lithium batteries

AlN/Co nanocomposite thin films were fabricated by pulsed laser deposition and investigated as new anode materials for lithium-ion batteries for the first time. The combination of electrochemically inactive AlN and Co in nanometer scale boosted the electrochemical performance of the thin films surprisingly. A high reversible capacity of 555 mAh·g⁻¹ after 100 discharge–charge cycles at a current density of 500 mA·g⁻¹ is obtained for the AlN/Co nanocomposite thin films, and 372 mAh·g⁻¹ can be retained at a high rate up to 16C, exhibiting promising cycle stability and rate capability. The electrochemical reaction mechanism study reveals that Co nanoparticles could not only provide high electronic conductivity for the thin films, which facilitate the thorough decomposition of AlN in the initial discharge process, but also react with Li₃N to form a new species Co₂N during charge process, thus ensuring large capacity and high reversibility of AlN/Co nanocomposite thin films in subsequent cycles. This study provides a new perspective to design advanced electrode materials for lithium-ion batteries.