Roles of Ti in Electrode Materials for Sodium-Ion Batteries

Abstract

Sodium-ion batteries offer a promising alternative to lithium-ion batteries due to their low cost, environmental friendliness, high abundance of sodium, and established electrochemical process. However, problems, such as low capacity, low storage voltage and capacity fade of electrode materials, must be resolved for the applications of sodium ion batteries. Many Ti-containing compounds were reported as cathode and anode materials, but very few studies focus on the role of Ti in electrodes used in sodium-ion batteries. This paper systemically reviews the roles of Ti in electrodes of sodium ion batteries. The Ti 4+ /Ti 3+ redox couple is a good choice for anodes due to its low potential and it exhibits different storage voltages in different structures. Although Ti 4+ does not participate in charge transfer in cathodes, it can indirectly enhance the capacity, cycling life and rate performance via structure change, cation order-disorder transition, and its interaction with the crystal lattice structure. This review will provide a new insight in designing and understanding novel high-performance electrodes. Keywords: sodium ion batteries, cathode, anode, titanium-based composite, order-disorder phase transition possibility of releasing fluorine gas becomes an environmental issue in large-scale production (Gover et al., 2006). Unlike LiFePO 4 , the olivine NaFePO 4 is thermally unstable in ambient environment and has to be produced (Kim et al., 2015) by the ion exchange of Li + in olivine LiFePO 4 with Na + , which complicates the production and increases cost (Oh et al., 2012). The commercial success of layered-LiCoO 2 in lithiumion batteries (Mizushima et al., 1980) has prompted extensive investigation of its sodium counterpart Na x TMO 2 (TM: Ni, Mn, Co, Ti) which crystallize into layered or tunneled structures depending on sodium content. The layered-structure consists of TM-O and Na-O layers. Compared to Li + , Na + has a larger radius and stronger interaction with O 2−. The sodiumlayered structure is further divided into O3, P3, P2, and O2. The O and P represent the octahedral and trigonal prismatic coordination environment of alkali ions, respectively; 3 and 2 describe the number of TM layers of repeated stacking (Delmas et al., 1980). The oxides P2/O3-Na x CoO 2 , Na x MnO 2 Na x VO 2 and Na x NiMnO 2 etc. are also investigated (Delmas et al.

FeTiO3 as Anode Material for Sodium‐Ion Batteries: from Morphology Control to Decomposition

“…The higher capacity retention observed for the FTO_hyd70 sample is in turn related to the electrochemical activity of the layered titanate as insertion like anode material. The layered structure characterized by huge interlayer distance allows for facile insertion/de‐insertion of Na ions and thus in improved stability upon cycling respect to a conversion‐type anode material, as already reported for similar systems . The performance of the FTO_hyd70 are not directly comparable with the highly promising literature data for layered titanate systems− as in our case the layered titanate is only a fraction of the active material, in which also Fe 2 O 3 is present.…”

“…The layered structure characterized by huge interlayer distance allows for facile insertion/de‐insertion of Na ions and thus in improved stability upon cycling respect to a conversion‐type anode material, as already reported for similar systems . The performance of the FTO_hyd70 are not directly comparable with the highly promising literature data for layered titanate systems− as in our case the layered titanate is only a fraction of the active material, in which also Fe 2 O 3 is present. Moreover, the formulation of the anode mixture in terms of binder and relative ratio of carbon : binder : active materials has not been optimized to obtain the best possible performance, goal that was out of the scope of the present study.…”

Flexible Na batteries

“…Natural wood fibers and oxidized wood fibers have been successfully used to fabricate paper-like anodes used in NIBs, as shown in Figure 3A, where wood fibers were oxidized by using 2,2,6,6-tetramethylpiperidine-1-oxyl-mediated. 57,58 However, almost all of these compounds suffer from poor electrical conductivity and ionic conductivity. The oxidized carbon paper delivered a reversible capacity of~260 mAh g −1 with an initial coulombic efficiency of~72%.…”

“…34,[54][55][56] Due to the low redox potential of the Ti 4+/3+ couple of 0.4-1.0 V, Ti-based oxides have been widely used as Na battery anodes on the basis of an intercalation-type mechanism. 57,58 However, almost all of these compounds suffer from poor electrical conductivity and ionic conductivity. Nanocrystallization treatments and conductive material coatings have been found to improve their electrochemical performance.…”

Advanced MoSe2/Carbon Electrodes in Li/Na‐Ions Batteries

“…Numerous members of metal‐based materials have been summarized in detail, like MoS 2 , TiO 2 , and V‐based materials . Among them, MoS 2 , as the important brother of MoSe 2 , has been summarized systematically overviewed.…”