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

Abstract

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 cm2 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 ∼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.

Lignin‐derived carbon materials for catalysis and electrochemical energy storage

“…In addition, heteroatom doping and loading of sodium storage particles on lignin‐derived hard carbon could also effectively improve the sodium storage performance. Zhang et al [ 112 ] used lignin as a carbon source to synthesize N, P co‐doped hard carbon microspheres with controlled microstructure and morphology by an emulsion‐solvent evaporation method mediated by (NH 4 ) 2 HPO 4 (Figure 13a). The results showed that N, P‐heteroatom co‐doping led to an increased electrical conductivity of the material, in addition to appropriate particle size (10–20 μm in the sphere diameter) and specific surface area (7.7–14.4 m 2 g −1 ), the harmonious coexistence of graphite microcrystals and disordered regions, a larger average layer spacing between graphite phases, and the moderate presence of mesopores and macropores.…”

“…Reproduced with permission: Copyright 2021, John Wiley and Sons. [112] | 293 T A B L E 4 Comparison of the sodium storage properties of different lignin-derived carbon materials Materials Reversible capacity Rate capability References C-1300 297 mAh g −1 (50 cycles, 50 mA g −1 ) 116 mAh g −1 (2.5 A g −1 ) [ 108] NLC 374 mAh g −1 (500 cycles, 25 mA g −1 ) 223 mAh g −1 (0.1 A g −1 ) [ 109]PL-1300 270 mAh g −1 (100 cycles, 50 mA g −1 ) 102 mAh g −1 (0.5 A g −1 )[ 111] 0.20NPL-1300 248 mAh g −1 (200 cycles, 100 mA g −1 ) 111 mAh g −1 (1 A g −1 )[ 112] HCM55-1400 316 mAh g −1 (150 cycles, 30 mA g −1 ) 161 mAh g −1 (0.3 A g −1 )[ 114] CLRSs 210 mAh g −1 (300 cycles, 125 mA g −1 ) 60 mAh g −1 (2.5 A g −1 )[ 115] CNF 122 mAh g −1 (350 cycles, 50 mA g −1 ) 25 mAh g −1 (1 A g −1 )[ 116] PL-CNFs 247 mAh g −1 (200 cycles, 100 mA g −1 ) 80 mAh g −1 (1 A g −1 )[ 117] E-KL/CA-C 340 mAh g −1 (200 cycles, 50 mA g −1 ) 103 mAh g −1 (0.4 A g −1 )[ 118] LC 202 mAh g −1 (100 cycles, 15 mA g −1 ) 45 mAh g −1 (0.15 A g −1 )[ 119]…”

A review on the effects of doping elements on the properties and applications of lignin-based carbon materials

“…58 Phosphorus can enhance the charge leaving domains of carbon atoms and form active sites of carbon materials at edge positions. Zhang et al 59 could easily convert lignin into nanoporous N and P co-doped hard carbon microspheres using an emulsion-solvent evaporation process, and electrochemical measurements of sodium-ion batteries showed that such ligninderived carbon microspheres also follow the widely accepted adsorption-intercalation sodium storage mechanism. They exhibit quite excellent sodium storage performance, such as large reversible and low voltage capacity, high initial coulombic efficiency (78.7-82.4%), good rate capability, and long cycle stability.…”

Locally Curved Surface with CoN4 Sites Enables Hard Carbon with Superior Sodium‐Ion Storage Performances at −40 °C

“…[2,3] However, the limited specific capacity and unsatisfactory Coulombic efficiency seriously limit the commercial application of hard carbon anode materials in sodium-ion batteries. [4,5] Recently, numerous solutions have been attempted to improve the electrochemical performance of hard carbon, including expanding interlayer d-spacing to accelerate intercalation and diffusion of Na + in graphitic-like domains; [6] providing more active adsorption sites on the surface by doping heteroatoms (e.g., N, [7] S, [8] F, [9] P, [10] etc.) and grafting functional groups; [11] optimizing the porous structure to form Na x+ (0≤x≤1) cluster storage within suitable pores; [12][13][14] and improving the initial Coulombic efficiency (ICE) by controlling the specific surface area and shielding defects.…”