Voltage fade prevents effective use of the excess capacity and represents the most crucial technical challenge faced by Li-and Mn-rich cathode materials (LMR) in modern batteries.Although oxygen release has been arguably considered as an initiator for the failure mechanism, its prerequisite driving force has yet to be fully understood. Herein, relying on the in-situ nanoscale sensitive coherent X-ray diffraction imaging (BCDI) technique, we are able to track the dynamic structure evolution of the LMR cathode. The results, surprisingly, reveal that continuous nanostrain accumulation arose from lattice displacement in nano-domain structures during cell operation is the original driving force for detrimental structure degradations together with oxygen loss that triggers the well-known rapid voltage decay in LMR. By further leveraging primary to multi-particle structure and electrode-level as well as atomic scale observations, we demonstrate that the heterogeneous nature of the LMR cathode inevitably causes pernicious phase displacement which cannot be eliminated by the previous trials. With these fundamental discoveries, we propose the structural design strategy to mitigate the lattice displacement and inhomogeneous electrochemical/structural evolutions, thereby achieving stable voltage and capacity profiles. These findings highlight the significance of lattice displacement in voltage decay mechanism and will inspire a wave of efforts to unlock the potential of the broad-scale commercialization of LMR cathode material.

The high conductive TiO(2) nanoneedles film is first employed as a support matrix for immobilizing model enzyme, cytochrome c (cyt c) to facilitate the electron transfer between redox enzymes and electrodes. Reversible and direct electron transfer of cyt c is successfully achieved at the nanostructured TiO(2) surface with the redox formal potential (E(0)') of 108.0 +/- 1.9 mV versus Ag|AgCl and heterogeneous electron transfer rate constant (k(s)) of 13.8 +/- 2.1 s(-1). Experimental data indicate that cyt c is stably immobilized onto the TiO(2) nanoneedles film and maintains inherent enzymatic activity toward H(2)O(2). On the basis of these results, the cyt c-TiO(2) nanocomposits film is capable of sensing H(2)O(2) at a suitable potential, 0.0 V (vs Ag|AgCl), where not only common anodic interferences like ascorbic acid, uric acid, 3,4-dihydroxyphenylacetic acid but also a cathodic interference, O(2), are effectively avoided. Besides high selectivity, the present biosensor for H(2)O(2) shows broad dynamic range and low detection limit. These remarkable analytical advantages, as well as the characteristic of TiO(2) nanoneedles film such as high conductivity, biocompatibility, and facile ability to miniaturize establishes a novel approach to detection of extracellular H(2)O(2) released from human liver cancer cells.

Here, we report on a novel superoxide anion (O2(*-)) biosensor based on direct electron transfer of copper, zinc-superoxide dismutase (Cu, Zn-SOD) at zinc oxide nanodisks surface for in vivo tracking of O2(*-) in bean sprouts. Direct electron transfer of SOD is achieved at ZnO nanodisks film prepared by a one-step electrodeposited method, with a high heterogeneous electron rate constant of 17 +/- 2 s(-1). Spectroscopic data demonstrate that SOD strongly immobilized onto the nanostructured ZnO surfaces processes its inherent activity toward O2(*-) dismutation. A combination of the facilitated direct electron transfer and the bifunctional enzymatic catalytic activities of the SOD substantially provides a dual electrochemical approach to determination of O2(*-) with high selectivity, wide linear range, long stability, and good reproducibility. In particular, SOD adsorbed on the ZnO nanodisks film is capable of sensing O2(*-) cathodically at a very positive potential, 0 mV (vs Ag|AgCl), where the common interfering species such as hydrogen peroxide, uric acid, ascorbic acid, and 3,4-dihydroxyphenylacetic acid were effectively avoided. The excellent analytical performance of the present O2(*-) biosensor, combined with the remarkable characteristics of nanostructured ZnO films, such as biocompatibility, ease of preparation, and facile to miniaturize, paves an electrochemical way for reliable and durable in vivo determination of O2(*-) in bean sprouts.

Fabrication of two-dimensional (2D) nanomaterials by conjugated polymers attracts increasing interest on account of their potential applications in optoelectronic devices. Precise control over the shape and size of the 2D nanostructures, however, is still challenging. We have developed a series of 2D rectangular micelles by hierarchical self-assembly of poly­(3-hexylthiophene) (P3HT)-b-poly­(ethylene glycol) (PEG) in i-PrOH. The aspect ratios and the sizes of the 2D rectangular micelles are controlled by the ratios of P3HT and PEG blocks, and the sizes of these 2D micelles are strongly concentration-dependent. Large and complex assembled architectures can be obtained in highly concentrated solutions. It is found that the block copolymers first assemble into fibers and then reorganize into 2D rectangular micelles with π–π interactions playing a key role in the formation of the 2D micelles. This offers a new method to prepare 2D nanostructures with controllable shapes and sizes for organic electronic devices.

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