La‐doped Porous Fe2O3 Nanorods as Advanced Anodes for Lithium/Sodium Ion Batteries and Sulfur Host for Li‐Sulfur Batteries

Abstract Transition metal oxides are investigated as electrochemically active anodes for several years due to the merits of high specific capacity, low cost, abundant resources and controllable synthesis. But the poor cycle performances have hindered their further wide application. Herein, porous La‐doped FeOOH nanorods have been synthesized through a facile hydrothermal method, which could be transformed into porous La‐doped Fe 2 O 3 (Fe 2 O 3 ‐La) via a simple heating process. Compared with the undoped Fe 2 O 3 , the Fe 2 O 3 ‐La showed larger surface area, higher specific capacities and more stable cycle performances for lithium/sodium ion batteries. In addition, as an advanced sulfur host for lithium‐sulfur batteries, the Fe 2 O 3 ‐La also displayed much more excellent cycle and rate performances than the undoped Fe 2 O 3 . The superior electrochemical performances of the Fe 2 O 3 ‐La may could be attributed to the doping of La, which could induce more porous morphology and offer more reactive sites. The positive effects of La‐doping for electrochemical performances of porous Fe 2 O 3 nanorods provide novel insights for further applications of rare earth metal doping.