Abstract:

LiMn₂O₄ nanoparticles are facilely synthesized using a sol–gel processing method. Graphene is added to LiMn₂O₄ electrode aiming at increasing specific capacity and improving rate capability. In order to further improve cycling stability of LiMn₂O₄/graphene electrode, atomic layer deposition (ALD) is used to deposit ultrathin ZnO coating composed of six ZnO ALD layers and modify the surface of either LiMn₂O₄/graphene electrode or individual LiMn₂O₄ particles to form nanoarchitectured LiMn₂O₄/graphene/ZnO electrodes. Both ZnO-ALD-modified LiMn₂O₄/graphene electrodes demonstrate enhanced cycling performance at 1C, retaining the final discharge capacity above 122 mA h g⁻¹ after 100 electrochemical cycles, which is higher than 115 mA h g⁻¹ of pristine LiMn₂O₄/graphene electrode and 109 mA h g⁻¹ of bare LiMn₂O₄ electrode. The improved electrochemical performance of nanoarchitectured LiMn₂O₄/graphene/ZnO electrodes can be attributed to the cooperative effects from high electronic conductivity of graphene sheets to facilitate electron transportation and effective protection of ZnO ALD coating to restrict Mn dissolution and electrolyte decomposition.