Abstract
We graft an electrically conductive poly(aniline-co-anthranilic acid) (PAAA) polymer capable of interacting with Si particles onto chitosan, a natural hydrophilic polymer, to form a chitosan-grafted-PAAA (CS-g-PAAA) copolymer, and use it as a new water soluble polymeric binder for Si anodes to relieve the physical stress resulting from Si volume change during charge/discharge cycles. The carboxylic acid functional groups within the PAAA structure, as well as the chitosan functional groups, bind to silicon particles to form a stable 3D network, resulting in high adhesion. Because the binder is conductive, the electrode using the CS-g-PAAA-8 : 1 with an optimal composition ratio of CS to PAAA of 8 : 1 shows a high initial capacity of 2785.6 mA h g−1, and maintains a high capacity of 1301.0 mA h g−1 after 300 cycles. We also extract chitosan directly from crab shells, and fabricate a Si@ECS-g-PAAA electrode by grafting PAAA onto the extracted-chitosan (ECS). This electrode records an initial capacity of 3057.3 mA h g−1, and maintains a high capacity of 1408.8 mA h g−1 with 51.4% retention after 300 cycles. Overall, we develop a polymeric binder with outstanding cell properties, ease of fabrication, and high water solubility for Si anodes by grafting a conductive PAAA onto chitosan.
Highlights
Lithium ion batteries are in high demand for portable electronic devices, electric vehicles, and large-scale energy storage systems because of their high energy density, long cycle life, and light weight
The polymeric binders were designed to provide both strong adhesion to Si and electrical conductivity (Scheme S1†)
The current was used to form a new solid electrolyte interface (SEI) layer, causing a reduced coulombic efficiency (CE). These results suggest that the introduction of poly(aniline-co-anthranilic acid) (PAAA) to CS was effective as an Si binder, but the poor adhesion of the binder in the presence of excess PAAA reduced CE and the retention capacity of the electrode
Summary
Lithium ion batteries are in high demand for portable electronic devices, electric vehicles, and large-scale energy storage systems because of their high energy density, long cycle life, and light weight. Energy consumption patterns are changing with the growing popularity of LIBs, and this has led to more extensive research on the development of high-capacity active materials for LIBs with enhanced energy density and durability.[1,2,3]. Si, undergoes a large volume change (up to 320%) in the lithiation/delithiation process, resulting in the pulverization and electrical isolation of silicon particles. This forms an unstable solid electrolyte interface (SEI) layer on the Si surface, and the repeated charge/discharge process arising from the continuous use of Li+ ions causes the electrode to experience a rapid decline in capacity.[4,5,6]
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