Kunjie Zhu

Hollow bean-pod-like SiO2-supported-SnO2/C nanocomposites for durable lithium and sodium storage

In order to better resolve the large volume expansion problem of SnO2-based anode materials, a hollow bean-pod-like SiO2-supported-SnO2/C nanostructure with a sufficient internal void space is designed. Dual voids exist in this structure in combination with a SiO2 support in the core and carbon as an outside shell, providing triple guarantees to improve the performance of SnO2-based anode materials for Li and Na storage. As a result, after 550 charge/discharge cycles, a discharge capacity of 649 mA h g−1 can still be obtained for Li storage, and a discharge capacity of 104 mA h g−1 can still be maintained after 1000 charge/discharge cycles for Na storage.

Synthesis of coral-like Fe2N@C nanoparticles and application in sodium ion batteries as a novel anode electrode material

Fast development of low-cost sodium ion batteries (SIBs) has boosted research efforts to identify proper anode materials, and now more attention is paid on carbon composites with better performance than simplex compounds. According to the explored different kinds of anode materials for SIBs in the past, only a few works are about transition metal nitrides. Herein a carbon-coated iron nitride was synthesized and applied for the first time in sodium ion batteries (SIBs), and the primary mechanism was detected via in situ XRD confirming Fe2N activity during discharge in SIBs. Fe2N nanoparticles as anodes in SIBs showed better stability than most of the materials reported in SIBs. The cycling performance of the synthesized coral-like Fe2N@C nanoparticles was significantly promoted compared to the pure nitride, and the improved performance of the carbon coated coral-like Fe2N suggests that more explorations about nitride electrode materials for SIBs are needed.

Enhanced thermoelectric performance in p-type Mg 3 Sb 2 via lithium doping

The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective, nontoxicity and environment friendly characteristics. However, the intrinsically p-type Mg3Sb2 shows low figure of merit (zT=0.23 at 723 K) for its poor electrical conductivity. In this study, a series of Mg3−x Li x Sb2 bulk materials have been prepared by high-energy ball milling and spark plasma sintering (SPS) process. Electrical transport measurements on these materials revealed significant improvement on the power factor with respect to the undoped sample, which can be essentially attributed to the increased carrier concentration, leading to a maximum zT of 0.59 at 723 K with the optimum doping level x = 0.01. Additionally, the engineering zT and energy conversion efficiency are calculated to be 0.235 and 4.89%, respectively. To our best knowledge, those are the highest values of all reported p-type Mg3Sb2-based compounds with single element doping.