Pressure-Dependent Electrochemical Behavior of Di-Lithium Rhodizonate Cathodes

Abstract

Herein, we investigate the electrochemical properties of the high-capacity organic cathode material di-lithium rhodizonate (Li 2 C 6 O 6 ) under different applied mechanical loads. We demonstrate, through a combination of pressure-dependent voltammetry and electrochemical impedance spectroscopy, that the charge-transfer kinetics at the cathode/electrolyte interface is strongly impacted by the magnitude of the load applied to the cathode. At low pressures, lithium rhodizonate displays untenably high charge-transfer impedances toward lithiation and delithiation. As the load applied to the cathode material is increased, the chargetransfer impedance decreases, reflecting a reduction in the overpotential associated with lithiation and delithiation. Furthermore, pressure-dependent galvanostatic cycling reveals that cells cycled at high pressures exhibit improvements in their overall capacity retention when compared with their low-pressure counterparts. Using a combination of postmortem X-ray diffraction and first-principles calculations, we show that, in the absence of sufficient external load, lithium rhodizonate converts from its redox-active structure to a redox-inactive structure, resulting in the observed rapid capacity fade. As the pressure applied to the electrode is increased, this phase transition is suppressed, resulting in improvements in both long-term stability and electrochemical kinetics.

Microstructure and mechanical properties of electrochemically cycled ice‐templated Li 4 Ti 5 O 12 sintered anodes

“…Finally, this study investigated how electrochemical cycling influenced compressive strength, but another consideration is how compression influences the electrochemical properties. Some materials have been reported to have electrochemical properties, which are sensitive to applied pressure 50 . An unexplored area for these sintered electrodes is whether varying the compressive forces influences the electrochemical properties of the material with all other physical properties kept nominally equivalent in the cell.…”

“…Some materials have been reported to have electrochemical properties, which are sensitive to applied pressure. 50 An unexplored area for these sintered electrodes is whether varying the compressive forces influences the electrochemical properties of the material with all other physical properties kept nominally equivalent in the cell.…”

Carbonyl Chemistry for Advanced Electrochemical Energy Storage Systems

“…72 In addition, lithium-ion storage of Li 2 C 6 O 6 is realized by the sequential reduction of the two redox active orthoquinones, resulting in the formation of two lithiated enediols (Figure 3a). 73 Notably, the pressure-dependent electrochemical properties of Li 2 C 6 O 6 have been studied under different applied mechanical loads. It was demonstrated that the crystallographic structure serves as an important factor for cycling durability and the irreversible phase transition causes the redox inactive feature of the Li 2 C 6 O 6 electrode (Figure 3b).…”

“…Importantly, the dilithium rhodizonate salt (Li 2 C 6 O 6 ) can be prepared from the myo-inositol derived from phytic acid, manifesting the great potential in the practical applications, which has been evaluated in LIBs (uptake capacity of four Li + ions down to 1.5 V) . In addition, lithium-ion storage of Li 2 C 6 O 6 is realized by the sequential reduction of the two redox active ortho -quinones, resulting in the formation of two lithiated enediols (Figure a) . Notably, the pressure-dependent electrochemical properties of Li 2 C 6 O 6 have been studied under different applied mechanical loads.…”

Double Doping of Semiconducting Polymers Using Ion‐Exchange with a Dianion

“…Aromatic oxocarbon anions and dianions represent a pathway to examining the role of the charge state of counterions in doped semiconducting polymers. [26,27] Conjugated cyclic oxocarbon species, including 1,2-benzoquinone and 1,4-benzoquinone dianions, [28] pentacarboxycyclopentadienyl (CPDE), [29] squarate, [30] croconate, [31][32][33][34][35] and rhodizonate [36] have reversible and robust electrochemical properties, and have been examined in lithium batteries, [28,37] ion sensors, [29] and artificial receptors. [33] Tethering of the counterion to a polymeric backbone (as a PIL) facilitates ion-exchange while preventing the infiltration of the cation into the doped film eliminating questions of infiltration of ion pairs that arise with ionic liquids.…”