High-capacity and ultrastable lithium storage in SnSe2-SnO2@NC microbelts enabled by heterostructures.

The ingenious design of high-performance tin-based lithium-ion batteries (LIBs) is challenging due to their poor conductivity and drastic volume change during continuous lithiation/delithiation cycles. Herein, we present a strategy to confine heterostructured SnSe2-SnO2 nanoparticles into macroscopic nitrogen-doped carbon microbelts (SnSe2-SnO2@NC) as anode materials for LIBs. The composites exhibit an excellent specific capacity of 436.3 mA h g-1 even at 20 A g-1 and an ultrastable specific capacity of 632.7 mA h g-1 after 2800 cycles at 5 A g-1. Density Functional Theory (DFT) calculations reveal that metallic SnSe2-SnO2 heterostructures endow the lithium atoms at the interface with high adsorption energy, which promotes the anchoring of Li atoms, and enhances the electrical conductivity of the anode materials. This demonstrates the superior Li+ storage performance of the SnSe2-SnO2@NC microbelts as anode materials.

Polyoxometalate steric hindrance driven chirality-selective separation of subnanometer carbon nanotubes.

Subnanometer single-chirality single-walled carbon nanotubes (SWCNTs) are of particular interest in multiple applications. Inspired by the interdisciplinary combination of redox active polyoxometalates and SWCNTs, here we report a cluster steric hindrance strategy by assembling polyoxometalates on the outer surface of subnanometer SWCNTs via electron transfer and demonstrate the selective separation of monochiral (6,5) SWCNTs with a diameter of 0.75 nm by a commercially available conjugated polymer. The combined use of DFT calculations, TEM, and XPS unveils the mechanism that selective separation is associated with tube diameter-dependent interactions between the tube and clusters. Sonication drives the preferential detachment of polyoxometalate clusters from small-diameter (6,5) SWCNTs, attributable to weak tube-cluster interactions, which enables the polymer wrapping and separation of the released SWCNTs, while strong binding clusters with large-diameter SWCNTs provide steric hindrance and block the polymer wrapping. The polyoxometalate-assisted modulation, which can be rationally customized, provides a universal and robust pathway for the separation of SWCNTs.