Search

Sodium-ion batteries (SIBs) have broad applications in the field of power grid energy storage owing to their significant cost advantages. Although the 3D framework structure of NaTi 2 (PO 4) 3 with a sodium superionic conductor (NASICON) has recently been regarded as a promising anode material in SIBs, the low inherent electrical conductivity of NaTi 2 (PO 4) 3 has hindered its practical application to batteries. However, since a number of research studies have shown that the conductivities of composite materials can be improved by carbon doping or coating, the carbon-coated NaTi 2 (PO 4) 3 @C (NTP@C) composite is expected to show excellent electrochemical performance in SIBs. In general, the production of NTP@C requires two steps (i.e. sample preparation and carbon coating), and the development of a one-step in situ preparation of NTP@C is desirable. In the present work, NTP@C microspheres with carbon concentrations of 1.4% and 4.95% were prepared in situ by a simple spray method followed by calcination. Of these, the NTP@C with a carbon content of about 4.95% displayed superior properties, delivering a high capacity of 105.26 mA h/g at a current rate of 5 C for the initial cycle, and presenting long-term cycling stability with a slow capacity decay of about 0.018% per cycle over 2000 cycles. The excellent electrochemical performance of the NTP@C microspheres can be attributed to the improved conductivity due to carbon coating and the enhanced stability provided by the microsphere structure. Thus, NTP@C is a promising alternative anode material for SIBs. Image 1 • A facile in-situ preparation of NaTi 2 (PO 4) 3 @C was proposed via one-step method. • The obtained composite with various carbon content shows micro spherical morphology. • The composite with 5% carbon content has excellent electrochemical properties in SIBs. • The coated carbon of NaTi 2 (PO 4) 3 @C enhanced the anodic conductivity and durability. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIB) have wide applications in the field of energy storage due to their low cost. Currently, due to its higher theoretical discharge capacity, tin and tin-based compounds are expected to become SIB anode materials. Here, 2D SnS 2 nanosheets with thickness of about 20 nm loaded on reduced graphene oxide (RGO) material (SnS 2 /RGO) was synthesized by a hydrothermal method, which display superior properties. When the denseness of current is 100 m A/g, the discharge capacity of the first cycle is as high as 956.1 m Ah/g, and the initial Coulombic efficiency is up to 60.0%. From the third cycle to the 200th cycles, the capacity decline rate of each cycle is about 0.13%; after 200 cycles the discharge capacity is still 443.4 m Ah/g. This outstanding performance is ascribed to the composite structure of SnS 2 /RGO, which helps to alleviate the stress of volume change during sodium ion insertion and extraction and enhances the conductivity of the SnS 2 material. Image 1 • SnS 2 electrode material was prepared by hydrothermal method. • The SnS 2 material loaded on RGO to improve the electrochemical performance. • At a current density of 100 mA/g, the initial discharge capacity is as high as 841.4 mAh/g. • After 100 cycles, the high discharge capacity of 471.1 mAh/g was still obtained. [ABSTRACT FROM AUTHOR]