Sieving carbons promise practical anodes with extensible low-potential plateaus for sodium batteries

Abstract

Non-graphitic carbons are promising anode candidates for sodium-ion batteries, while their variable and complicated microstructure severely limits the rational design of high-energy carbon anodes that could accelerate the commercialization of sodium-ion batteries as is the case for graphite in lithium-ion batteries. Here, we propose sieving carbons, featuring highly tunable nanopores with the tightened pore entrances, as high-energy anodes with extensible and reversible low-potential plateaus (<0.1 V). It is shown that the tightened pore entrance blocks the formation of the solid electrolyte interphase inside the nanopores and enables sodium clustering to produce the plateau. Theoretical and spectroscopic studies also show that creating a larger area of sodiophilic pore surface leads to an almost linearly increased number of sodium clusters and controlling the pore body diameter guarantees the reversibility of sodium cluster formation, producing a sieving carbon anode with a record-high plateau capacity of 400 mAh g–1. More excitingly, this approach to preparing sieving carbons is potential to be scalable for modifying different commercial porous carbons.

Role of Defects, Pores, and Interfaces in Deciphering the Alkali Metal Storage Mechanism in Hard Carbon

“…However, an extra intermediate Li layer can fit in the same pore size so that the average Li pore-filling picture appears the same as Na's. The electronic analysis results are consistent with experimental NMR experiments 28,30 revealing semimetallic Na clustering and DFT-machine learning calculations 32 depicting partial electron transfer in the same range. K donates 40% of its valence charge to the carbon matrix.…”

“…Further, DFT has directly predicted that it is energetically favorable to form three to four Na layers within the graphitic layers, supporting that semimetallic Na cluster formation within the graphitic layers is the origin of the voltage plateau . Furthermore, DFT computations combined with machine learning on nongraphitic carbon models analyzed the local environment of the inserted Na . Maximum charge transfer was observed at the initial stages of sodiation, where ionic Na resides near vacancies on the sp 2 plane.…”

“… 31 Furthermore, DFT computations combined with machine learning on nongraphitic carbon models analyzed the local environment of the inserted Na. 32 Maximum charge transfer was observed at the initial stages of sodiation, where ionic Na resides near vacancies on the sp 2 plane. On the other hand, only partially ionic Na was detected for Na pore clustering, with charge transfer between 0.2 and 0.6, producing a voltage plateau.…”

Low-content SnO2 nanodots on N-doped graphene: lattice-confinement preparation and high-performance lithium/sodium storage

“…Second, the smaller specific surface area of the composite (132 m 2 g −1 ) as compared to that of the counterpart (156 m 2 g −1 ) facilitated alleviation of the undesirable SEI side effects, and contributed to the reversible capacity. 61…”

Design Strategies for Sodium Electrode Materials: Solid-State Ionics Perspective

“…nano 1 (single phase) nano 1 : nano 2 nano 1 : macro 2 amorphous 1 (single phase) amorphous 1 : amorphous 2 amorphous 1 : nano 2 amorphous 1 : macro 2 γ 1,2 = surface tension of phase 1, 2; v 1,2 = mole volume of phase 1, 2; v Li,1 = partial molar volume of Li in phase 1; r 1,2 = particle size of phase 1, 2; r 0 = atomistic size;  m G 1,2 = melting free enthalpy of phase 1, 2; μ i ex = excess chemical potential of Li interstitial; μ n ex = excess chemical potential of electrons. 题组 88…”