In-Situ Resource Utilization of Pectin and Bosch Carbon for Energy Storage

Various waste sources available during long-duration crewed space exploration missions have been targeted for application in electrochemical energy storage technologies. Pectin, a biopolymer found in plant cell walls, can be extracted from food waste and implemented into various polymer electrolyte formats. This study presents an innovative process simplification and combination with a de-esterification technique to produce repeatable pectin characteristics over ranges of functional group concentration, process yield, and biopolymer molecular weight. Pectin with a low degree of esterification produced through this process has been characterized and formed into hydrogel electrolytes that exhibit an array of beneficial properties typically split between solid and liquid electrolyte forms. Biopolymer hydrogel electrolytes with extremely high ionic conductivity have been electrochemically and physically characterized, and then implemented into supercapacitor coin cells with various valorized carbon electrodes. As supercapacitors, the hydrogels exhibit excellent efficiency, long-term cycling stability, and robust thermal cycling characteristics. Furthermore, carbon produced as a byproduct of a wider system of In-Situ Resource Utilization (ISRU) has been implemented in both sodium-ion batteries with other resources expected to be available on missions to the moon and Mars. ISRU soft carbon was compared with commercial hard carbon in batteries and activated biomass carbon when applied to supercapacitors with pectin electrolytes. These ISRU carbon electrodes are demonstrated to compare favorably with leading commercial alternatives and perform significantly better than another ISRU alternative material (TiO2). The ISRU supercapacitors and batteries produced as part of this study exhibited properties well within the expected range for developmental energy storage technologies of their kinds, and even outperformed in terms of specific power density in both cases.