As an n-type wide-bandgap (E g = 3.6 eV) semiconductor, SnO 2 is one of the most intensively studied materials owing to its myriad technologically important applications such as gas sensors and lithium rechargeable batteries. [1][2][3][4][5][6][7][8] To date, various nanostructures of SnO 2 , such as nanoparticles, [2] nanorods/belts/arrays, [3] nanotubes, [4] nanodisks, [5] nanoboxes, [6] hollow spheres, [7] and mesoporous structures, [8] have been prepared.Recently, hollow inorganic micro-and nanostructures have attracted considerable attention because of their promising applications such as nanoscale chemical reactors, efficient catalysts, drug-delivery carriers, and photonic building blocks. [9][10][11][12][13][14][15][16][17][18][19][20] Until now the general approach for preparation of hollow COMMUNICATIONS

Graphene has aroused intensive interest because of its unique structure, superior properties, and various promising applications. Graphene nanostructures with significant disorder and defects have been considered to be poor materials because disorder and defects lower their electrical conductivity. In this paper, we report that highly disordered graphene nanosheets can find promising applications in high-capacity Li ion batteries because of their exceptionally high reversible capacities (794−1054 mA h/g) and good cyclic stability. To understand the Li storage mechanism of graphene nanosheets, we have prepared graphene nanosheets with structural parameters tunable via different reduction methods including hydrazine reduction, low-temperature pyrolysis, and electron beam irradiation. The effects of these parameters on Li storage properties were investigated systematically. A key structural parameter, Raman intensity ratio of D bands to G bands, has been identified to evaluate the reversible capacity. The greatly enhanced capacity in disordered graphene nanosheets is suggested to be mainly ascribed to additional reversible storage sites such as edges and other defects.

Conjugated polymeric molecules have been heralded as promising electrode materials for the next-generation energy-storage technologies owing to their chemical flexibility at the molecular level, environmental benefit, and cost advantage. However, before any practical implementation takes place, the low capacity, poor structural stability, and sluggish ion/electron diffusion kinetics remain the obstacles that have to be overcome. Here, we report the synthesis of a few-layered two-dimensional covalent organic framework trapped by carbon nanotubes as the anode of lithium-ion batteries. Remarkably, upon activation, this organic electrode delivers a large reversible capacity of 1536 mAh g −1 and can sustain 500 cycles at 100 mA g −1 . Aided by theoretical calculations and electrochemical probing of the electrochemical behavior at different stages of cycling, the storage mechanism is revealed to be governed by 14-electron redox chemistry for a covalent organic framework monomer with one lithium ion per C=N group and six lithium ions per benzene ring. This work may pave the way to the development of high-capacity electrodes for organic rechargeable batteries.

The preparation of SnO2 nanotubes with coaxially grown carbon nanotube overlayers with good conformal control of shape and size is reported. The SnO2‐core/carbon‐shell nanotubes (see Figure) are excellent reversible lithium‐ion storage compounds combining the best features of carbon (for cyclability) and SnO2 (for capacity). These structures deliver high specific capacity (∼ 540–600 mA h g–1) and good cyclability (0.0375% capacity loss per cycle).