Lignin-Based Mesoporous Hollow Carbon@MnO₂ Nanosphere Composite as an Anodic Material for Lithium-Ion Batteries

The lignin-based mesoporous hollow carbon@MnO₂ nanosphere composites (L-C-NSs@MnO₂) were fabricated by using lignosulfonate as the carbon source. The nanostructured MnO₂ particles with a diameter of 10~20 nm were uniformly coated onto the surfaces of the hollow carbon nanospheres. The obtained L-C-NSs@MnO₂ nanosphere composite showed a prolonged cycling lifespan and excellent rate performance when utilized as an anode for LIBs. The L-C-NSs@MnO₂ nanocomposite (24.6 wt% of MnO₂) showed a specific discharge capacity of 478 mAh g^-1 after 500 discharge/charge cycles, and the capacity contribution of MnO₂ in the L-C-NSs@MnO₂ nanocomposite was estimated ca. 1268.8 mAh g^-1, corresponding to 103.2% of the theoretical capacity of MnO₂ (1230 mAh g^-1). Moreover, the capacity degradation rate was ca. 0.026% per cycle after long-term and high-rate Li⁺ insertion/extraction processes. The three-dimensional lignin-based carbon nanospheres played a crucial part in buffering the volumetric expansion and agglomeration of MnO₂ nanoparticles during the discharge/charge processes. Furthermore, the large specific surface areas and mesoporous structure properties of the hollow carbon nanospheres significantly facilitate the fast transport of the lithium-ion and electrons, improving the electrochemical activities of the L-C-NSs@MnO₂ electrodes. The presented work shows that the combination of specific structured lignin-based carbon nanoarchitecture with MnO₂ provides a brand-new thought for the designation and synthesis of high-performance materials for energy-related applications.