Solvated Sodium Storage via a Coadsorptive Mechanism in Microcrystalline Graphite Fiber

Abstract

various sodium storage chemistry. For example, metal alloys, [6][7][8] oxides/chalcogenides, [9][10][11] phosphorus, [12][13][14] and carbonaceous materials [15][16][17] have been extensively studied as potential anodes for SIBs. Among all these anode materials, graphite exhibits a unique sodium storage electrochemistry when coupled with different electrolytes, which is of great interest. In detail, a negligible amount of sodium ions can be intercalated into the graphite structure when coupled with ester-based electrolytes because of weak binding between Na + and the graphite interlayer. [18][19][20] While sodium can be reversibly stored in graphite in ether-based electrolytes. [21,22] The answer to the riddle is that Na + and ether molecules can cointercalate between the graphene layers in graphite. [23][24][25][26] The unique sodium storage mechanism confers graphite electrodes with remarkable reversibility and fast sodium intercalation kinetics, opening a new avenue toward exploiting graphite as a promising anode for advanced SIBs. [27][28][29] However, there is still a lack of investigation at the atomic scale, such as the solvated Na + structure and possible changes during charging/discharging.Motivated by these findings, the related electrochemical performance and sodium storage mechanism have been extensively investigated, including the structural changes and sodium storage mechanisms of graphite in the sodium storage Graphite has been widely accepted for its reversible solvated sodium cointercalation mechanism into the graphite layers in ether-based electrolytes. However, the cointercalation suffers from insufficient Coulombic efficiency with high redox potentials, which significantly limits its energy output. Herein, instead of the conventional solvated Na + cointercalation into the graphite, a new coadsorptive mechanism is proposed through the microcrystalline graphite fiber (MCGF), which can reversibly store the solvated Na + at the ribboned grain boundaries and in the mesopores of the MCGF. The mechanism is manifested by various advanced spectroscopy techniques, including in situ synchrotron small-angle X-ray scattering to track the long-periodic structure evolution and ex situ synchrotron X-ray absorption fine structure to verify the interaction of solvated Na and graphite layers. The origin of the boosted rate-capability and reversibility is further revealed by density functional theory simulations and aberration-corrected transmission electron microscopy. As a proof-of-concept, the MCGF electrode exhibits high initial coulombic efficiency (92.5%), fast-charging (within 4 min), and enhanced cycling stability (≈98% retention after 800 cycles). The results provide a new understanding of the sodium storage mechanism in graphite-based materials, which may inspire further exploration of carbon electrodes for Na-ion batteries.

Intercalation Reaction of Molybdenum Trioxide Cathode for Rechargeable Ion Batteries

“…Composite with carbon materials, polymers, Mxene, and other conductive materials are one of the most commonly used modification strategies to optimize the conductivity [102] and cycle stability of the MoO 3 cathode. Composite carbon materials [103] include carbon nanotubes, [56,104] graphene, [54,95] which are used as substrates, [95] coatings, [100] or three‐dimensional conductive networks [54] to combine with MoO 3 , thus playing a crucial role in the ion transport and structural stability of MoO 3 . In the composite with graphene, the MoO 3 /graphene self‐supporting film prepared through rapid microwave hydrothermal reaction has higher cycle stability than the original [54] .…”

ZIF-8 coating on graphite: a high-rate and long-term cycling anode for sodium-ion capacitors

“…7F). 24,25,[35][36][37] When other inactive components (including aluminum foil, acetylene black, and poly(vinylidene uoride) (PVDF)) are included for calculation, the energy and power densities will decrease to about 29% of the above values (Fig. S10 ESI †).…”

“…18 This solvent co-intercalation can avoid the desolvation step, thus possessing fast reaction kinetics, which opens a new avenue to employ graphite as a promising negative electrode in SICs. 19,20 Until now, properties of Na + -solvent co-intercalation into graphite have been extensively investigated, including: (1) revealing the intercalation mechanism of Na in the (t)-GIC system using operando X-ray diffraction; 21 (2) surface layer evolution on the graphite surface during Co-intercalation of sodium-solvent; 22 (3) developing novel graphite structures (such as few-layer graphitic carbon, 23 freestanding microcrystalline graphite fiber 24 ) toward fast and long-term co-intercalation of solvated Na + . Despite these advances, irreversible capacity in the initial cycle is always observed, resulting in a relative ICE value (about 50%).…”

Enhanced Polarization Effect of Flexible Magnetoelectric PVDF-TrFE/Fe3O4 Smart Nanocomposites for Nonvolatile Memory Application

“…Information storage is crucial to the development of the Internet of Things (IoT) and construction of the digital twin-enabled metaverse. , Magnetoelectric random access memory is regarded as a promising candidate in memory application. The magnetoelectric (ME) coupling of nanocomposites allows magnetism to be controlled by an electric field, providing the possibility to store binary information by the magnetization direction of the ferromagnetic layer .…”