Sodium/Lithium-Ion Transfer Reaction at the Interface between Low-Crystallized Carbon Nanosphere Electrodes and Organic Electrolytes

Abstract

Carbon nanosphere (CNS) electrodes are the candidate of sodium-ion battery (SIB) negative electrodes with small internal resistances due to their small particle sizes. Electrochemical properties of low-crystallized CNS electrodes in dilute and concentrated sodium bis­(trifluoromethanesulfonyl) amide/ethylene carbonate + dimethyl carbonate (NaTFSA/EC + DMC) were first investigated. From the cyclic voltammograms, both lithium ion and sodium ion can reversibly insert into/from CNSs in all of the electrolytes used here. The cycling stability of CNSs in concentrated electrolytes was better than that in dilute electrolytes for the SIB system. The interfacial charge-transfer resistances at the interface between CNSs and organic electrolytes were evaluated using electrochemical impedance spectroscopy. In the Nyquist plots, the semicircles at the middle-frequency region were assigned to the parallel circuits of charge-transfer resistances and capacitances. The interfacial sodium-ion transfer resistances in concentrated organic electrolytes were much smaller than those in dilute electrolytes, and the rate capability of CNS electrodes in sodium salt-concentrated electrolytes might be better than in dilute electrolytes, suggesting that CNSs with concentrated electrolytes are the candidate of SIB negative electrode materials with high rate capability. The calculated activation energies of interfacial sodium-ion transfer were dependent on electrolyte compositions and similar to those of interfacial lithium-ion transfer.

Anionic Effects on Li-Ion Activity and Li-Ion Intercalation Reaction Kinetics in Highly Concentrated Li Salt/Propylene Carbonate Solutions

“…The apparent activation energy estimated from the Arrhenius plot of 1/ R ct was 62 kJ mol –1 (Figure S6), which is not significantly different from the value shown in Figure a. The E a (app) value for the [LiClO 4 ]/[PC] = 1/3 HCE was estimated as 71 kJ mol –1 , which was larger than that for the [LiClO 4 ]/[PC] = 1/10 low-concentration electrolyte (LCE) and is comparable to previously reported values. − Abe and co-workers reported an increase in E a (app) for solid electrolyte/liquid electrolyte and carbonaceous electrode/electrolyte interfaces , at high salt concentrations in the range of 3–5 M. They speculated that the cleavage of the ion pairs of Li + -anions at the interface requires a larger Δ G * than that for the desolvation of Li + ions in HCEs . However, here a question arises whether the attractive force between Li + and ClO 4 – is stronger than that between Li + and PC in the studied electrolytes.…”

“…The and is comparable to previously reported values. 58−61 Abe and co-workers reported an increase in E a (app) for solid electrolyte/liquid electrolyte 58 and carbonaceous electrode/electrolyte interfaces 59,60 at high salt concentrations in the range of 3−5 M. They speculated that the cleavage of the ion pairs of Li + -anions at the interface requires a larger ΔG* than that for the desolvation of Li + ions in HCEs. 58 However, here a question arises whether the attractive force between Li + and ClO 4 − is stronger than that between Li + and PC in the studied electrolytes.…”

Kinetics of Interfacial Ion Transfer in Lithium-Ion Batteries: Mechanism Understanding and Improvement Strategies

“…Kondo et al investigated interfacial Li + transfer kinetics at carbonaceous electrodes in concentrated electrolytes. , The E a in concentrated 4 mol kg –1 LiN­(SO 2 CF 3 ) 2 (LiTFSA)/EC was 75 kJ mol –1 , which was much larger than the 56 kJ mol –1 value in 0.9 mol kg –1 LiTFSA/EC. This observation is similar to those at a model interface of solid electrolyte/liquid electrolyte .…”

“…First, we focus on interfacial Li + transfer at transition metal oxides , as positive electrodes and Li 4 Ti 5 O 12 and graphite as negative electrodes. After that, we introduce a detailed analysis on a model interface, solid electrolyte/liquid electrolyte, to discuss the mechanism and rate-determining step. − For graphite negative electrodes, the effects of electrolyte composition and solid electrolyte interphase (SEI) were also studied. − In the latter part, we present strategies to accelerate the interfacial Li + transfer with an eye to electrolyte compositions, surface modifications, and types of battery reactions. − Finally, we emphasize the importance of frequency factors (i.e., pre-exponential factors) as well as activation energies to dominate the kinetics of interfacial Li + transfer. − …”

Effect of Solid Electrolyte Interphase on Sodium-Ion Insertion and Deinsertion in Non-Graphitizable Carbon

“…11,12 Researchers have explored alternative carbon materials, including graphitizable carbon and carbon nanospheres, as negative electrodes for SIBs. Graphitizable carbon has shown a reversible capacity like LIBs, 10,13,14 whereas carbon nanospheres have shown a reversible capacity exceeding 100 mAh g −1 , 15,16 particularly in lowcrystallized forms. Non-graphitizable carbon, with its porous structure, has emerged as a promising candidate for the negative electrodes of SIBs because of its ability to store ions in graphene interlayers within the pores.…”