清洁能源化学与材料实验室知识库

Large Li₂O₂ aggregations can produce high‐capacity of lithium oxygen (Li‐O₂) batteries, but the larger ones usually lead to less‐efficient contact between Li₂O₂ and electrode materials. Herein, a hierarchical cathode architecture based on different discharge characteristics of α‐MnO₂ and Co₃O₄ is constructed, which can enable the embedded growth of large Li₂O₂ aggregations to solve this problem. Through experimental observations and first‐principle calculations, it is found that α‐MnO₂ nanorod tends to form uniform Li₂O₂ particles due to its preferential Li⁺ adsorption and similar LiO₂ adsorption energies of different crystal faces, whereas Co₃O₄ nanosheet tends to simultaneously generate Li₂O₂ film and Li₂O₂ nanosheets due to its preferential O₂ adsorption and different LiO₂ adsorption energies of varied crystal faces. Thus, the composite cathode architecture in which Co₃O₄ nanosheets are grown on α‐MnO₂ nanorods can exhibit extraordinary synergetic effects, i.e., α‐MnO₂ nanorods provide the initial nucleation sites for Li₂O₂ deposition while Co₃O₄ nanosheets provide dissolved LiO₂ to promote the subsequent growth of Li₂O₂. Consequently, the composite cathode achieves the embedded growth of large Li₂O₂ aggregations and thus exhibits significantly improved specific capacity, rate capability, and cyclic stability compared with the single metal oxide electrode.