Se‐Induced Fibrous Nano Red P with Superior Conductivity for Sodium Batteries

Red phosphorus shows great promise as a high‐capacity anode material for Na batteries. Such electrodes that suffered from the fracturing impact of volume change during cycling can be effectively improved by 1D nanomaterials. However, the synthesis of 1D red phosphorus has rarely been studied and employed in sodium batteries. Here, a simple selenium‐induced method to generate fibrous nano red phosphorus is presented. It turns out that a small amount of selenium can not only induce high‐quality fibrous nano red phosphorus from commercial red phosphorus, but also benefit qualitatively to the sodium ionic conductivity. Interestingly, the selenium dopant can also manipulate the chemical state of phosphorus leading to valence tunability which is able to tolerate structural stability under the Na‐rich or Na‐poor condition. As a result, the optimal fibrous nano red phosphorus used as anode outperforms over the traditional red phosphorus ≈6 and ≈10 times in terms of rate performance and cycle stability, respectively. Furthermore, as employed for sodium metal anode protection, the symmetrical cell cycling maintains long stable at a low polarization voltage for over 1000 h. The full cell performs excellent cycling stability of 1500 cycles at 3 C and high‐rate performance up to 30 C. This study provides a Se‐induced method to synthesize 1D red P. The small amount of Se cannot only induce high‐quality fibrous nano red P from commercial red P, but also benefit qualitatively to Na conductivity. Interestingly, Se dopant can also manipulate the chemical state of P leading to valence tunability that tolerates structural stability under the Na‐rich/poor condition.