MgO‐Template Synthesis of Extremely High Capacity Hard Carbon for Na‐Ion Battery

Abstract

Extremely high capacity hard carbon for Na-ion battery, delivering 478 mAh g À1 , is successfully synthesized by heating a freeze-dried mixture of magnesium gluconate and glucose by a MgO-template technique. Influences of synthetic conditions and nano-structures on electrochemical Na storage properties in the hard carbon are systematically studied to maximize the reversible capacity. Nano-sized MgO particles are formed in a carbon matrix prepared by pre-treatment of the mixture at 600 8C. Through acid leaching of MgO and carbonization at 1500 8C, resultant hard carbon demonstrates an extraordinarily large reversible capacity of 478 mAh g À1 with a high Coulombic efficiency of 88 % at the first cycle.

Enabling Fast Na+ Transfer Kinetics in the Whole‐Voltage‐Region of Hard‐Carbon Anodes for Ultrahigh‐Rate Sodium Storage

“…Previous reports in the literature state that the interlayer spacing smaller than 0.35 nm is not sufficient for Na + intercalation [1,10,17] while nanopores with smaller diameters (<1.0 nm) are not conducive to the filling of sodium clusters. [7,9] To simulate the Na + intercalation in the graphitic domains of HCs, a representative bilayer graphene model [31,36] (AB stacking) of 5 × 5 supercell with varied interlayer distance and a 15 Å vacuum space along the y-axis were considered. The Na + storage behavior within a short graphitic layer (SGL) is denoted as SGL-0.36, SGL-0.38, and SGL-0.40, respectively, and a bilayer model with a distance of 1 nm between the top and bottom layers has been built to simulate the nanopores among graphitic domains (Figure 5a and Figures S23,S24, Supporting Information).…”

“…[4][5][6][7] Hard carbons (HCs) have attracted extensive attention with suitable potential versus Na + /Na, good structural stability, decent coulombic efficiency, superior reversible capacity etc., and are considered as the most feasible anode materials for further commercialization. [8][9][10] Nevertheless, the unsatisfied rate capability of HCs (generally < 5 A g -1 ) represents the primary constraint in their practical applications, as well as the underlying structure-performance correlation is a substance of controversial discussion.Typical HCs comprise a large number of short-range-ordered graphitic domains and internal micropore domains (or voids between graphitic domains). [11] The graphitic-domain with proper interlayer distance and the internal-nanopore-domain are both believed to be capable of accommodating sodium ions.…”

“…[4][5][6][7] Hard carbons (HCs) have attracted extensive attention with suitable potential versus Na + /Na, good structural stability, decent coulombic efficiency, superior reversible capacity etc., and are considered as the most feasible anode materials for further commercialization. [8][9][10] Nevertheless, the unsatisfied rate capability of HCs (generally < 5 A g -1 ) represents the primary constraint in their practical applications, as well as the underlying structure-performance correlation is a substance of controversial discussion.…”

Hard Carbon Anodes for Next‐Generation Li‐Ion Batteries: Review and Perspective

“…[ 12,31,38–41 ] Beyond LIBs, hard carbons have also been demonstrated to be potential anodes in other alkali metal batteries such as sodium/potassium ion batteries. [ 42–55 ] The latest research progress of carbonaceous anode materials for sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) has been reviewed many times. [ 34,36–41 ] However, not all issues in LIBs have been covered in these literatures.…”

In Situ (Operando) Electrochemical Dilatometry as a Method to Distinguish Charge Storage Mechanisms and Metal Plating Processes for Sodium and Lithium Ions in Hard Carbon Battery Electrodes

“…[ 1d,g,4 ] Even higher values of 478 mAh g −1 are possible for tailor‐made carbons as recently demonstrated by Kamiyama et al. [ 5 ]…”