Dual‐ion batteries have been developed as a promising technology in recent years, but their high self‐discharge rate leading to low coulombic efficiency (CE) limits their practical applications. This work provides a deft strategy to circumvent this issue by using FeFe(CN)6 as the anode material for hosting Na+ cations, in combination with a graphite cathode for accommodating the bis(trifluoromethanesulfonyl)imide anions (TFSI−). The relatively high bonding force between FeFe(CN)6 and Na+ can hinder self‐extraction of ions from the electrodes, thereby decreasing the self‐discharge rate. The FeFe(CN)6 nanospheres, synthesized by a facile solution reaction method, are well crystallized and dispersed. Na+ insertion into the FeFe(CN)6 cube is determined by cyclic voltammetry (CV), galvanostatic charge–discharge, and X‐ray diffraction tests, suggesting a reversible process. Under a current of 0.05 mA cm−2 the batteries present an acceptable discharge plateau within 1.5–0.7 V and a well‐defined capacity of 75.0 mAh g−1, with a high CE above 98.5% (±0.1%); under 0.2 mA cm−2, cells display a high cyclability of 83.0% capacity retention for 100 cycles, with an excellent CE exceeding 99.6% (±0.1%). Moreover, the batteries exhibit a low self‐discharge rate with a resting capacity decay of 0.32% h−1, outperforming many of the reported dual‐ion cells.
A 1280 × 1,024 In0.53Ga0.47As short wave infrared (SWIR) focal plane array (FPA) detector with a planar-type back-illuminated process has been fabricated. With indium bump flip-chip bonding techniques, the InGaAs photodiode arrays were hybrid-integrated to the CMOS readout integrated circuit (ROIC) with correlated double sampling (CDS). The response spectrum is 0.9–1.7 μm. The test results show that the dark current density is 2.25 nA/cm2 at 25 °C, the detectivity D* is up to 1.1 × 1013 cm · Hz1/2/W, the noise electron is as low as 48 e− under correlated double sampling mode, the quantum efficiency is 88% at 1550 nm, and the operability is more than 99.9%. Moreover, the dark current and noise electron have been studied theoretically in depth. The results indicate that the diffusion current is the main contribution of the dark current, and the readout integrated circuit noise electron is the main source of FPA noise.
Gated InGaAs avalanche photodiodes are often used for synchronous single-photon detection in the near-infrared wavelengths of 1310 and 1550 nm for optical fiber communication. However, one of the main obstacles limiting their application is the difficulty in extracting a weak photon-induced avalanche pulse from background noise. Here, we describe a double-pulse superposition technique to detect the signal, which uses a synchronized pulse to raise the avalanche signal above the discriminating threshold so the avalanche signal can be easily detected. This technique provides a simple idea for a practical gated single-photon detector to sense avalanche signals since the parasitic capacitance signal from an applied external circuit is unavoidable and will always be coupled to the avalanche signal. Under the same measurement conditions, a comparison was made with the conventional capacitive balance technique, and the experimental results showed a high agreement between the effects of the two signal extraction techniques under several nanoseconds scale gating widths, and the doublepulse superposition technique is highly efficient and easy to implement even under complicated background noise.
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