Junjie Niu

We developed a magnesium/sodium (Mg/Na) hybrid battery using a hierarchical disk-whisker FeSe2 architecture (HD-FeSe2) as the cathode material and a modified dual-ion electrolyte. The polarizable Se2– anion reduced the Mg2+ migration barrier, and the 3D configuration possessed a large surface area, which facilitated both Mg2+/Na+ cation diffusion and electron transport. The dual-ion salts with NaTFSI in ether reduced the Mg plating/stripping overvoltage in a symmetric cell. The hybrid battery exhibited an energy density of 260.9 Wh kg–1 and a power density of 600.8 W kg–1 at 0.2 A g–1. It showed a capacity retention of 154 mAh g–1 and a Coulombic efficiency of over 99.5% under 1.0 A g–1 after 800 long cycles. The battery also displayed outstanding temperature tolerance. The findings of 3D architecture as cathode material and hybrid electrolyte provide a pathway to design a highly reliable Mg/Na …

Due to the high capacity and the high discharge potential, Ni-rich layered cathode materials are considered as a class of promising cathode material and attracting considerable attention. Because of the Li+/Ni2+ cation mixing, Li residues, overcharging, crystal orientation of the secondary particles, poor cycling stability and rate capability are usually received in lithium ion batteries. In this presentation, we introduce a layered NMC811 with Ni-gradients by using metal-organic framework (MOF) as precursor ( Cell Reports Physical Science , 3 (2022), 100767). The self-healing phase by forming a cation mixing layer on the surface of particles effectively improved the structural stability by suppressing the phase transition and internal cracks upon cycling. In the half-cell battery, an initial capacity of 203.5 mAh/g at 0.1 C and a capacity retention of 88.5% after 300 cycles at 1/3 C were obtained. The …

Biofilm is a microbiome complex comprising different bacterial colonies that typically adhere to device surfaces in water, which causes serious medical issues such as indwelling infections and outbreaks. Here we introduce a non-nanoparticle, flexible anti-biofilm hygiene coating consisting of lithocholic acid (LCA), zinc pyrithione (Zn) and cinnamaldehyde (Cn) (named as LCA-Zn-Cn) that largely prevents the bacteria adhesion to various water device surfaces such as stainless steel and glass through a synergistic mechanism (ACS Applied Bio Materials, 5 (2022) 3991). The existing chelated groups on LCA and Cn attract plenty of bacteria via hydrophobic interaction. Both bactericidal reaction by grafting biocidal groups from both LCA and Cn and bacteriostatic reaction by inhibiting cell division via zinc ions (Zn) lead to a largely improved bacteria/biofilm prevention. The antibacterial performance was assessed by …

To meet the rapidly growing market in electrical vehicles (EVs) and portable electronic devices, a battery with high energy density is required. In order to reach this goal, Li metal, is considered as the most promising candidate as anode. However, the dendrite forming, low Coulombic efficiency (CE), and unstable solid electrolyte interphase (SEI) pose big challenges in applying Li metal in batteries. Here we introduce a dual-layer coated Li metal surface, which consists a lithium carboxylate organic layer and a doped MXene layer. The porous organic layer increases the wetting of electrolyte and forms a thin solid electrolyte interface (SEI). While the doped MXene leads to about 50% reduced thickness of inorganic-rich components among the SEI layer. A low overpotential of less than 30 mV over 1000 h cycling in symmetric cells was received. The functional groups along with the good electronic conductivity and …

The surface modification of lithium metal anode poses a promising way in reaching high energy-density batteries. Here we introduce a dual-layer interphase that consists of an in-situ formed lithium carboxylate organic layer and an ultra-thin BF3-doped monolayer Ti3C2 MXene on Li metal surface (Shang, Shovon, Wong, Niu. Advanced Materials, 35 (2023) 2210111). The honeycomb-structured organic layer increases the wetting of electrolyte due to the large surface area, leading to a thin solid electrolyte interface (SEI). While the BF3-doped monolayer MXene provides abundant active sites for lithium homogeneous nucleation and growth, resulting in about 50% reduced thickness of inorganic-rich components among the SEI layer. A low overpotential of less than 30 mV over 1000 h cycling in symmetric cells was received. The functional BF3 groups along with the excellent electronic conductivity and smooth …

A foldable battery with high flexibility provides great potential in various wearable electronic devices for health and fitness tracking, chronic disease management, performance monitoring, navigation tracking, and portable gears for soldiers. We report a highly flexible, self‐healing Zn‐ion battery with a free‐standing cathode that is composed of a 3D gear‐like NH4V4O10@C composite on carbon paper. The battery retained a capacity of up to 102.4 mAh g−1 even after being folded 60 times with a high angle of 180°. An aqueous hydrogel consisting polyvinyl alcohol, glycerin and Zn(CF3SO3)2 was used as electrolyte, which showed as high as 580 % tensile strain under a loading weight of 78 N. The battery exhibited a better capacity retention of over 100 mAh g−1 and Coulombic efficiency of over 99.8 % after cutting and twisting to 90°, thereby indicating a great self‐healing performance. The gear‐like …

The recalcitrant nature of perfluoroalkyl substances (PFAS) urge scientists to discover solutions to permanently remove PFAS contaminations from water with less energy in contrast to incineration. In this presentation, we will introduce a duo-functional tri-metallic-oxide (f-TMO) hybrid photocatalyst that was synthesized via a facile process, which displayed both high adsorption capacity and high defluorination rate of a series of PFAS including PFOA, PFOS, PFHpA, PFHxA and PFBA due to the generated holes/electrons (h+/e-) and multi-radicals such as O2 •- and SO4 •- (Samuel, Shang, Niu. Chemosphere , 293 (2022) 133568). The Langmuir adsorption capacities up to 827.84 and 714.46 mg g-1 along with the adsorption efficiency of 99.8% and 99.4% for PFOS and PFOA were respectively achieved. A defluorination ratio of as high as 74.8% with PFOA and a ratio up to 67.6 …

A dual‐layer interphase that consists of an in‐situ‐formed lithium carboxylate organic layer and a thin BF3‐doped monolayer Ti3C2 MXene on Li metal is reported. The honeycomb‐structured organic layer increases the wetting of electrolyte, leading to a thin solid electrolyte interface (SEI). While the BF3‐doped monolayer MXene provides abundant active sites for lithium homogeneous nucleation and growth, resulting in about 50% reduced thickness of inorganic‐rich components among the SEI layer. A low overpotential of less than 30 mV over 1000 h cycling in symmetric cells is received. The functional BF3 groups, along with the excellent electronic conductivity and smooth surface of the MXene, greatly reduce the lithium plating/stripping energy barrier, enabling a dendrite‐free lithium‐metal anode. The battery with this dual‐layer coated lithium metal as the anode displays greatly improved electrochemical …