Improve the Electrochemical Performance of Na₂Ti₃O₇ Nanorod through Pitch Coating

Abstract

Na 2 Ti 3 O 7 is proposed as a potential anode for sodium ion batteries (SIBs) because of its advantages of low operating voltage, high energy density, and low cost. However, the low conductivity and the structural instability of the intercalated phase limit its practical application. Herein, Na 2 Ti 3 O 7 @C nanorod composites are prepared by using Na 2 Ti 3 O 7 as the active substance particles and pitch as the carbon precursor. Pitch is selected due to the characteristics of low crystallinity, easy graphitization, and porous structure after carbonization. The results of electrochemical performance tests show that the Na 2 Ti 3 O 7 @C composite electrode has a good rate performance and stable cycle stability. In addition, the electrode thickness expansion rate of the Na 2 Ti 3 O 7 @C composite (22.28%) is lower than that of pure Na 2 Ti 3 O 7 (117.51%). The improvement of electrochemical performances mainly benefit from the porous structure of the pitch carbon layer, which reduces the volume expansion of Na 2 Ti 3 O 7 material from the charge−discharge process, avoids the damage of the solid electrolyte interphase (SEI) film outside the Na 2 Ti 3 O 7 @C composites, and thus maintains the integrity of the structure to extend the service life. This work offers some new perceptions into the mechanism of carbon coating.

Achieving High Initial Coulombic Efficiency and Capacity in a Surface Chemical Grafting Layer of Plateau‐type Sodium Titanate

“…The superior cycling stability is attributed to the Al 2 O 3 heterostructure inducing the formation of a more stable and sodium fluoride‐rich SEI film that prevents continuous decomposition of the electrolyte, which is further discussed later. The performance achieved by Na 2 Ti 3 O 7 with heterogeneous is superior to most sodium titanate previously reported in the literature [11,12b,13,20–21,24,30] (Figure 3f).…”

Soft carbon in non-aqueous rechargeable batteries: a review of its synthesis, carbonization mechanism, characterization, and multifarious applications

“…, 10 4 S cm −1 of conductivity and only 22% volume expansion were obtained in one study. 137 The beneficial effect of the carbon coating was visualized using surface and cross-sectional SEM images before and after cycling. The emergence of large cracks seen in the uncoated sample was not observed in the coated sample.…”

Building a Stable Plateau-Type Na2Ti3O7 Anode Interface toward Advanced Sodium-Ion Batteries

“…27 Even with the enhancement in the cycling performance of carbon-coated samples, the rate of capacity retention after 100 cycles remains at only 65%. 28,29 The solid electrolyte interface (SEI) film on Na 2 Ti 3 O 7 is primarily composed of carbonates (Na 2 CO 3 ), semicarbonates (NaCO 3 R), chlorides (NaCl), fluorides (NaF), and poly(ethylene oxide)s. 30 Poly(ethylene oxide) and alkyl carbonates were discovered to be partially dissolved among these components, contributing to the instability of the SEI layer and negatively influencing battery performance. As a result, there is an urgent requirement to develop a straightforward and convenient method to enhance the interfacial stability of NTO anode materials, aiming to significantly improve the electrochemical performance of Na 2 Ti 3 O 7 anodes.…”

“…Nonetheless, the cycle life of NTO is still restricted, as the desertion/insertion of sodium may lead to microcracks on the anode electrode surface, which can lead to ongoing electrolyte decomposition and inadequate cycle stability. , According to previous reports, the capacity decay rate of layered structure Na 2 Ti 3 O 7 in 50 cycles can be as high as 70% . Even with the enhancement in the cycling performance of carbon-coated samples, the rate of capacity retention after 100 cycles remains at only 65%. , The solid electrolyte interface (SEI) film on Na 2 Ti 3 O 7 is primarily composed of carbonates (Na 2 CO 3 ), semicarbonates (NaCO 3 R), chlorides (NaCl), fluorides (NaF), and poly­(ethylene oxide)­s . Poly­(ethylene oxide) and alkyl carbonates were discovered to be partially dissolved among these components, contributing to the instability of the SEI layer and negatively influencing battery performance.…”