Regulating surface electron structure of PtNi nanoalloy via boron doping for high-current-density Li-O₂ batteries with low overpotential and long-life cyclability

The realization of high-efficiency, reversible, stable, and safe Li-O₂ batteries is severely hindered by the large overpotential and side reactions, especially at high rate conditions. Therefore, rational design of cathode catalysts with high activity and stability is crucial to overcome the terrible issues at high current density. Herein, we report a surface engineering strategy to adjust the surface electron structure of boron (B)-doped PtNi nanoalloy on carbon nanotubes (PtNiB@CNTs) as an efficient bifunctional cathodic catalyst for high-rate and long-life Li-O₂ batteries. Notably, the Li-O₂ batteries assembled with as-prepared PtNiB@CNT catalyst exhibit ultrahigh discharge capacity of 20510 mA·h/g and extremely low overpotential of 0.48 V at a high current density of 1000 mA/g, both of which outperform the most reported Pt-based catalysts recently. Meanwhile, our Li-O₂ batteries offer excellent rate capability and ultra-long cycling life of up to 210 cycles at 1000 mA/g under a fixed capacity of 1000 mA·h/g, which is two times longer than those of Pt@CNTs and PtNi@CNTs. Furthermore, it is revealed that surface engineering of PtNi nanoalloy via B doping can efficiently tailor the electron structure of nanoalloy and optimize the adsorption of oxygen species, consequently delivering excellent Li-O₂ battery performance. Therefore, this strategy of regulating the nanoalloy by doping nonmetallic elements will pave an avenue for the design of high-performance catalysts for metal-oxygen batteries.