Deformation-adaptive N,P-doped porous carbon nanofibers as a protective interlayer for stable Li metal anodes

Stress concentration acts as a key catalyst for Li dendrite growth, compromising the interfacial structure of Li metal batteries, which accelerates capacity degradation and increases safety risks. Consequently, managing Li deposition and alleviating stress are crucial for enhancing the reversibility of Li plating/stripping and extending battery life. Herein, we have developed a highly flexible film made of nitrogen and phosphorus co-doped porous carbon nanofibers (NPCNFs). The hierarchically porous structure of NPCNFs offers remarkable flexibility, effectively mitigating stress concentration during prolonged Li cycling. Additionally, the nitrogen and phosphorus-rich lithiophilic sites within the NPCNFs lower the nucleation barrier for Li metal, promoting a stable, bottom-up Li deposition model. This approach also circumvents the "tip effects" associated with residual stress. With these advantages, the Li metal anode, protected by an NPCNFs layer, achieves high coulombic efficiency and superior cyclability, maintaining performance over 1400 h with a low plating overpotential of just 13 mV. When paired with a sulfur cathode, the NPCNFs@Li || S full cells exhibit a long cycle life, retaining 63.3% capacity after 300 cycles. Notably, the corresponding pouch cells demonstrate robust electrochemical and structural stability under significant deformation, affirming the practicality and effectiveness of flexible carbon-based protective layers.