Na/Al Codoped Layered Cathode with Defects as Bifunctional Electrocatalyst for High-Performance Li-Ion Battery and Oxygen Evolution Reaction.

The rational design of bifunctional electrocatalyst through simple synthesis with high activity remains a challenging task. Herein, Na/Al codoped Li-excess Li-Ru-Ni-O layered electrodes are demonstrated with defects/dislocations as an efficient bifunctional electrocatalyst toward lithium-ion battery (LIB) and oxygen evolution reaction (OER). Toward LIB cathode, specific capacity of 173 mAh g-1 (0.2C-rate), cyclability (>95.0%), high Columbic efficiency (99.2%), and energy efficiency (90.7%) are achieved. The codoped electrocatalyst has exhibited OER activity at a low onset potential (270 mV@10 mA cm-2 ), with a Tafel slope 69.3 mV dec-1 , and long-term stability over 36 h superior to the undoped and many other OER electrocatalysts including the benchmark IrO2 . The concurrent doping resides in the crystal lattice (where Na shows the pillaring effect to improve facile Li diffusion), Al improves the stabilization of the layered structure, and defective structures provide abundant active sites to accelerate OER reactions.