摘要
Lignin is the second most abundant and the only nature polymer rich in aromatic units.Although aromatic-unit-rich precursors often yield soft carbon after carbonization,the side chains in lignin crosslink with the aromatic units and form a rigid three-dimensional(3D)structure which eventually leads to hard carbons.Through a graphene oxide-catalyzed decomposition and repolymerization process,we successfully reconstructed lignin by partially tailoring the side chains.Compared to directly carbonized lignin,the carbonized reconstructed lignin possesses significantly fewer defects,86%fewer oxygen-functionalities,82%fewer micropores,and narrower interlayer space.These parameters can be tuned by the amount of catalysts(graphene oxide).When tested as anode for K-ion and Na-ion batteries,the carbonized reconstructed lignin delivers notably higher capacity at low-potential range(especially for Na-storage),shows much-improved performance at high current density,and most importantly,reduces voltage hysteresis between discharge and charge process by more than 50%,which is critical to the energy efficiency of the energy storage system.Our study reveals that the voltage hysteresis in K-storage is much severer than that in Na-storage for all samples.For practical K-ion battery applications,the voltage hysteresis deserves more attention in future electrode materials design and the reconstruct ion strategy introduced in this work provides potential low-cost solution.
基金
This work is funded by Alberta Innovates through the Alberta Bio Future,Lignin Challenge 1.0 and Lignin Pursuit subprograms。
