Oxygen Vacancies of CeO2 Nanospheres by Mn-Doping: An Efficient Electrocatalyst for N2 Reduction under Ambient Conditions.

The electrochemical N2 reduction reaction (NRR) demonstrates a process of NH3 synthesis from N2 molecules under ambient conditions, which is environmentally friendly and recyclable. However, it requires an efficient electrocatalyst to activate inert N2 molecules, which is still difficult to satisfy. Recently, as an active NRR electrocatalyst and a typical metal oxide, CeO2 has featured ultrahigh thermal stability and the ability to apply heteroatom doping, which is an imperative approach importing oxygen vacancy by replacing metal ions with selective elements to greatly influence the activity of catalysts. Here, we analyze the unique properties of manganese dopants in modulating the activity of CeO2 nanospheres for NRR. It attains a larger NH3 yield of 27.79 µg h-1 mgcat-1 and a higher Faradaic efficiency of 9.1% than pure CeO2 at -0.30 V in 0.1 M HCl, with high electrochemical and structure stability. With calculations by density functional theory, the performance enhancement of Mn-doped CeO2 is also proved mathematically.

Face-lifting the surface of LiNi0.8Co0.15Al0.05O2cathode via Y(PO3)3to form anin situtriple composite Li-ion conductor coating layer with the enhanced electrochemical performance.

Due to the assets such as adequate discharge capacity and rational cost, LiNi0.8Co0.15Al0.05O2(NCA), a high-nickel ternary layered oxide, is regarded to be a favorable cathode contender for lithium-ion batteries. However, the superior commercial application is restricted by the surface residual alkaline lithium salt (LiOH or/and Li2CO3) of nickel-rich cathode materials, which will expedite the disintegration of the structure and the engendering of gas (CO2). Therefore, in this paper, we devise and fabricate a Y(PO3)3modified LiNi0.8Co0.15Al0.05O2(NCA), intending to optimize the surface residual alkaline lithium salt (antecedent deportation of H2O and CO2) while forming anin situtriple composite Li-ion conductor coating (Y(PO3)3-Li3PO4-YPO4) to enhance the electrochemical behavior. Under this method, the 2 mol% Y(PO3)3modified NCA electrode reveals exceptional rate capability (5 C/156.3 mAh g-1) and extraordinary cycle stability after 200 cycles (2 C/88.3%), whereas the original sample is only 5 C/123.1 mAh g-1and 2 C/71.2% after 200 cycles. Conspicuously, even under the draconian circumstances of the high temperature and the high rate at 55 °C/1 C, the 2 mol% Y(PO3)3modified NCA electrode sustains a high reversible capacity, with an admirable capacity retention rate of 89.4% after 100 cycles. These contented results signify that the surface remodeling tactic presents a viable scheme for ameliorating high-nickel materials' performance and appropriateness.

Utilizing dual functions of LaPO4to enhance the electrochemical performance of LiNi0.87Co0.09Al0.04O2cathode material.

In this paper, via a facile wet coating method, the LaPO4coating layer has been introduced onto the LiNi0.87Co0.09Al0.04O2(NCA) surface while a small part of La3+has also been doped on the surface to realize the dual functions modification of coating and doping. The morphology and structure of the samples were investigated by XRD, SEM and TEM measurements. The chemical compositions of the samples were analyzed via EDS and XPS data. The results showed that the coating of LaPO4and the doping of La3+were successfully achieved on the surface of NCA. Electrochemical tests indicate that the sample modified with 2 wt% LaPO4(L2-NCA) possesses the best electrochemical performance. After 100 cycles, compared with the capacity retention rate of pristine NCA of 87.1%/74.2% at 0.5 C at 25 °C/60 °C, L2-NCA showed better cycling stability, and the capacity retention rate increased to 96.0%/85.1%, respectively. Besides, the rate performance of the modified samples at 1 C, 2 C and 5 C were also significantly improved. These satisfactory results reveal that the surface modification of LaPO4provides a feasible scheme to uprate the performance of Ni-rich cathode materials.

Optimizing surface residual alkali and enhancing electrochemical performance of LiNi0.8Co0.15Al0.05O2cathode by LiH2PO4.

LiNi0.8Co0.15Al0.05O2(NCA), a promising ternary cathode material of lithium-ion batteries, has widely attracted attention due to its high energy density and excellent cycling performance. However, the presence of residual alkali (LiOH and Li2CO3) on the surface will accelerate its reaction with HF from LiPF6, resulting in structural degradation and reduced safety. In this work, we develop a new coating material, LiH2PO4, which can effectively optimize the residual alkali on the surface of NCA to remove H2O and CO2and form a coating layer with excellent ion conductivity. Under this strategy, the coated sample NCA@0.02Li3PO4(P2-NCA) provides a capacity of 147.8 mAh g-1at a high rate of 5 C, which is higher than the original sample (126.5 mAh g-1). Impressively, the cycling stabilities of P2-NCA under 0.5 C significantly improved from 85.2% and 81.9% of pristine-NCA cathode to 96.1% and 90.5% at 25 °C and 55 °C, respectively. These satisfied findings indicate that this surface modification method provides a feasible strategy toward improving the performance and applicability of nickel-rich cathode materials.

An Approach to Segment and Track-Based Pedestrian Detection from Four-Layer Laser Scanner Data.

Pedestrian detection is a critical perception task for autonomous driving and intelligent vehicle, and it is challenging due to the potential variation of appearance and pose of human beings as well as the partial occlusion. In this paper, we present a novel pedestrian detection method via four-layer laser scanner. The proposed approach deals with the occlusion problem by fusing the segment classification results with past knowledge integration from tracking process. First, raw point cloud is segmented into the clusters of independent objects. Then, three types of features are proposed to capture the comprehensive cues, and 18 effective features are extracted with the combination of the univariate feature selection algorithm and feature correlation analysis process. Next, based on the segment classification at individual frame, the track classification is conducted further for consecutive frames using particle filter and probability data association filter. Experimental results demonstrate that both back-propagation neural network and Adaboost classifiers based on 18 selected features have their own advantages at the segment classification stage in terms of pedestrian detection performance and computation time, and the track classification procedure can improve the detection performance particularly for partially occluded pedestrians in comparison with the single segment classification procedure.

Dual functions of zirconium metaphosphate modified high-nickel layered oxide cathode material with enhanced electrochemical performance.

High-nickel LiNi0.9Co0.1O2 cathode shows an enormous potential in next-generation high energy density lithium-ion batteries. However, its cation mixing and the second hexagon to the third hexagonal of phase transition (H2 - H3) pose severe challenges to its practical and commercial applications. In this work, zirconium metaphosphate is applied to optimize the microstructure near surface zone of LiNi0.9Co0.1O2 cathode material to suppress its cation mixing and the H2 - H3 phase transformation during long cycling process. It is found that single-atom or atomic group plays different roles in doping strategy due to their different thermodynamic properties. Specifically, Zr4+ tends to form a uniform doping to optimize crystal structure, while PO43- group presents a gradient distribution near the surface area and generates Li3PO4 coating layer to enhance the Li+ mass transfer. As a result, the modified LiNi0.9Co0.1O2 cathode shows an improved cycling stability with a high capacity retention of 93.7% after 100 cycles, whereas the bare LiNi0.9Co0.1O2 cathode only delivers a low capacity retention of 81.7%. This work highlights the critical role of thermodynamic properties of doped atoms toward the electrochemical performance and can be extended to other layered cathode materials.