Free-standing N,Co-codoped TiO2 nanoparticles for LiO2-based Li–O2 batteries†
Li–O2 batteries based on lithium superoxide (LiO2) would address the issues of significant polarization, low energy density and inferior cycle performance. However, LiO2 as an intermediate product in the discharge process is very active and could be readily disproportionated into Li2O2. Thus, it is challenging to find an appropriate cathode catalyst, which can stabilize the active discharge product LiO2. In this work, heteroatom N and Co codoped titanium dioxide nanoparticles grown on carbon fibers (N,Co-TiO2/CFs) are fabricated and employed as a non-noble metal cathode catalyst for Li–O2 batteries. LiO2 formed in the Li–O2 batteries can be repeatedly charged and discharged with a very low charge potential of approximately 3.0 V (vs. Li/Li+). N,Co-codoped TiO2 is proposed to be responsible for the generation of stable LiO2. This discovery opens a new way for the fabrication of non-noble metal cathode catalysts for high-performance LiO2-based Li–O2 batteries.