Cu3(PO4)2: Novel Anion Convertor for Aqueous Dual‑Ion Battery

Electrode materials which can reversibly react with anions are of interest for aqueous dual-ion batteries.Herein,we propose a novel anion electrode,Cu3(PO4)2,for constructing an aqueous dual-ion cell.The Cu3(PO4)2 electrode can operate in a quasi-neutral condition and deliver a reversible capacity of 115.6 mAh g^−1 with a well-defined plateau at−0.17 V versus Ag/AgCl.Its reaction mechanism shows that Cu3(PO4)2 decomposes into Cu2O and subsequently is converted into Cu during the initial discharge process.In the following charge process,Cu is oxidized into Cu2O.It suggests Cu3(PO4)2 reacts with OH−ions instead of PO43−ions after the initial discharge process and its potential thereby depends upon the OH−ions concentration in electrolyte.Additionally,an aqueous dual-ion cell is built by using pretreated Cu3(PO4)2 and Na0.44MnO2 as anode and cathode,respectively.During cycling,OH−ions and Na^+ions in electrolyte can be stored and released.Such a cell can provide a discharge capacity of 52.6 mAh g^−1 with plateaus at 0.70 and 0.45 V,exhibiting the potential of application.This work presents an available aqueous dual-ion cell and provides new insights into renewable energy storage and adjustment of the OH−ions concentration in aqueous buffer solution.

Enabling nickel ferrocyanide nanoparticles for highperformance ammonium ion storage

Prussian blue and its analogs are extensively investigated as a cathode for ammonium-ion batteries.However,they often suffer from poor electronic conductivity.Here,we report a Ni_(2)Fe(CN)_(6)/multiwalled carbon nanotube composite electrode material,which is prepared using a simple coprecipitation approach.The obtained material consists of nanoparticles with sizes 30-50 nm and the multiwalled carbon nanotube embedded in it.The existence of multiwalled carbon nanotube ensures that the Ni_(2)Fe(CN)_(6)/multiwalled carbon nanotube composite shows excellent electrochemical performance,achieving a discharge capacity of 55.1 mAh·g^(-1)at 1 C and 43.2 mAh·g^(-1)even at 15 C.An increase in the ammoniumion diffusion coefficient and ionic/electron conductivity based on kinetic investigations accounts for their high performance.Furthermore,detailed ex situ characterizations demonstrate that Ni_(2)Fe(CN)_(6)/multiwalled carbon nanotube composite offers three advantages:negligible lattice expansion during cycling,stable structure,and the reversible redox couple.Therefore,the Ni_(2)Fe(CN)_(6)/multiwalled carbon nanotube composite presents a long cycling life and high rate capacity.Finally,our study reports a desirable material for ammonium-ion batteries and provides a practical approach for improving the electrochemical performance of Prussian blue and its analogs.

A fast face detection architecture for auto-focus in smart-phones and digital cameras

Auto-focus is very important for capturing sharp human face centered images in digital and smart phone cameras. With the development of image sensor technology, these cameras support more and more highresolution images to be processed. Currently it is difficult to support fast auto-focus at low power consumption on high-resolution images. This work proposes an efficient architecture for an Ada Boost-based face-priority auto-focus. The architecture supports block-based integral image computation to improve the processing speed on high-resolution images; meanwhile, it is reconfigurable so that it enables the sub-window adaptive cascade classification, which greatly improves the processing speed and reduces power consumption. Experimental results show that 96% detection rate in average and 58 fps(frame per second) detection speed are achieved for the1080p(1920×1080) images. Compared with the state-of-the-art work, the detection speed is greatly improved and power consumption is largely reduced.

PNb_(9)O_(25) nanofiber as a high-voltage anode material for advanced lithium ions batteries

If the operating voltage of anode materials is below 1.0 V versus Lit/Li,the side reaction between electrolyte and anode materials will occur extensively.Thus,high-voltage anode materials have aroused interest recently.In this work,we report the preparation of PNb9O25 nanofiber via a facile electrospinning method.The PNb9O25 nanofiber shows the high rate performance and excellent cycling performance when it is used as anode in lithium ions batteries.For instance,the PNb9O25 nanofiber can deliver a capacity of 233,212.1,193.8,and 181.4 mA h g^(-1) at 0.2,1,3,and 6C,respectively.After 1000 cycles,it can reach at 134.3 mA h g^(-1) with capacity retention of 70.9%.Meanwhile,the ex situ X-ray photoelectron spectroscopy technique has been adopted to investigate the evolution in valence state of each element for PNb9O25 nanofiber.In addition,the PNb9O25 nanofiber is chosen as the anode material in lithium ion full cell in this work,demonstrating the potential for practical application.