NMR study for electrochemically inserted Na in hard carbon electrode of sodium ion battery

Abstract

The state of sodium inserted in the hard carbon electrode of a sodium ion battery having practical cyclability was investigated using solid state 23 Na NMR. The spectra of anode samples charged (reduced) above 50 mAh g -1 showed clear three components. Two peaks at

Structural and Electrochemical Properties of Hard Carbon Negative Electrodes for Sodium Secondary Batteries Using the Na[FSA]–[C₃C₁pyrr][FSA] Ionic Liquid Electrolyte

“…5,6 For example, several positive electrode materials like We have also investigated the charge-discharge behavior of hard carbon (HC) negative electrodes in this ionic liquid at 363 K. 10,11 HC is mainly composed of two structural domains, i.e., randomly-arranged graphene domains and their interstitial sites (pores), and its charge-discharge behavior as a negative electrode material for sodium secondary batteries has been well investigated in organic solvent electrolytes. [12][13][14][15][16][17][18][19][20] However, there have been few studies on the correlation of HC structure and its electrochemical behavior in ionic liquid electrolytes.…”

Expanded graphitic materials prepared from micro- and nanometric precursors as anodes for sodium-ion batteries

“…Thus, different carbon materials with diverse structures (micro-and nanostructures) and varied morphologies, usually with a certain degree of porosity and low-ordered structure consisting of few-layer graphite nanocrystallites, have been investigated for this application [12]. Among them, hard carbons are arguably the most promising candidates thus far [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], being able to deliver reversible capacities >300 mA h g -1 at low-to-moderate current rates with remarkable stability along cycling, although some aspects need to be improved for their implementation as anodes for SIBs, such as their relatively low coulombic efficiency in the first cycle, which is related to their high surface area and porosity, or their modest rate performance. The turbostratic structure of these materials, consisting in few-layer-stacked graphite nanocrystallites with high interlayer distances (0.37-0.40 nm), together with their inherent porosity (i.e.…”

The Role of Boron in B/C/N and B/C Materials as an Anode of Sodium Ion Batteries

“…On the other hand, electrochemical behavior of C/N materials and carbon is based on the insertion of Na + ion into the nano-pore among the small crystallites. [4][5][6] It should be the advantage that B/C/N and B/C materials had the capacity only by the intercalation.…”

“…However, graphite cannot be used as the anode of Na ion batteries because of the difficulties in intercalating Na into graphite. [1][2][3] Instead of graphite, hard carbon [4][5][6] and other materials have been studied as potential host materials for anodes of Na ion batteries. In the case of hard carbon as the matrix of anode, Na might not be intercalated into the layered structure, but is inserted into nano-pores among the boundaries of carbon crystals.…”

“…In the case of hard carbon as the matrix of anode, Na might not be intercalated into the layered structure, but is inserted into nano-pores among the boundaries of carbon crystals. [4][5][6] We have recently investigated the intercalation of Na into boron/ carbon/nitrogen (B/C/N) materials by using an electrochemical method as well as a chemical reaction method, and found that Na could be intercalated into a material that produces lower stage compounds. 7,8 The B/C/N materials with a graphite-like layered structure are types of hetero-atom substituted carbon alloys, 9 and have been prepared using a chemical vapor deposition (CVD) method or other methods.…”