Chitin and Chitosan—Structurally Related Precursors of Dissimilar Hard Carbons for Na-Ion Battery

We demonstrate that other polysaccharides, such as chitin and chitosan, can be as well up-and-coming parent materials of hard carbons

Joanna Conder; Cyril Vaulot; Cyril Marino; Claire Villevieille; Camélia Matei Ghimbeu

2019

Scholarcy highlights

  • Antibacterial, biodegradable, easy to functionalize and modify, naturally abundant, and nontoxic1, 2 – the list of chitin and chitosan properties is almost endless as is the number of applications for which these two linear polysaccharides are being extensively explored and in which they are already implemented
  • hard carbons derived from lignin, phenolic resins, and their mixture with pitch come to the fore owing to significantly higher carbon yield than that of cellulose-derived HC and decent electrochemical performance
  • Even if the HC-precursors are structurally related and their elemental composition is almost identical, they do not necessary convert into similar carbons during the thermal treatment as we demonstrate. At first glance it seems that both biopolymers, chitin and chitosan, undergo similar thermal decomposition with few percent mass loss between 30 and 100°C due to the evaporation of the physisorbed water followed by a major mass loss between 200 to 400°C caused by decomposition, depolymerization, and formation of char
  • Pyrolysis of two structurally similar bioprecursors, namely chitin and chitosan, yields dissimilar hard carbons in terms of porosity, surface chemistry and the presence of impurities. The latter can be removed from the material by simple acid-treatment without adversely affecting its structural and textural properties, as we showed on the example of chitosan-derived HC
  • HCs prepared from biopolymers or any other parent materials for energy storage applications very often required additional post-thermal treatment(s) and/or further tuning of their morphology, structure, and texture
  • Based on the results presented here we conclude that rich surface chemistry and micro-mesoporous texture of the chitin-derived HC promotes excessive decomposition of the electrolyte, leading to low first-cycle Coulombic efficiency
  • The latter limitation can be overcome by acid-washing, which is an effective remedy to tame continuously declining specific charge

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