Facile Synthesis of N,P-codoped Hard Carbon Nanoporous Microspheres from Lignin for High-Performance Anodes of Sodium-Ion Batteries

We demonstrate a facile emulsion-solvent evaporation process to easily convert lignin into nanoporous N,P-codoped hard carbon microspheres. The combined physiochemical characterizations indicate this material possesses micro-structure suitable for electrochemical energy storage. The electrochemical measurements of sodium ion battery (SIB) show that such lignin-derived carbon microspheres also follow the widely-accepted adsorption-intercalation Na-storage mechanism. The Na+ diffusion coefficient in as-obtained electrode could reach 10(-9) cm(2) s(-1). They exhibit quite excellent and balanced Na-storage performances, such as large reversible and low-voltage capacity (up to 307-336 and 229-246 mAh g(-1), respectively), high initial coulombic efficiency (78.7-82.4 %), and good rate performance as well as long cycling stability (e. g., retaining at 248 mAh g(-1) and a retention of similar to 92.2 % after running at 0.1 A g(-1) for 200 cycles). Consequently, this work not only provides a facile approach to realize high added-value utilization of lignin but also contributes to the development of eco-environmental batteries using low-cost materials.

Automated summary

A facile emulsion-solvent evaporation process was used to convert lignin into nanoporous N,P-codoped hard carbon microspheres, which exhibit excellent Na-storage performances suitable for electrochemical energy storage. The lignin-derived carbon microspheres follow the widely accepted adsorption-intercalation Na-storage mechanism, with a high Na+ diffusion coefficient and balanced capacity, efficiency, rate performance, and cycling stability.