Multiple uniform lithium-ion transport channels in Li6.4La3Zr1.4Ta0.6O12/Ce(OH)3 modified polypropylene composite separator for high-performance lithium metal batteries.

Lithium (Li) metal anodes (LMAs) are regarded as leading technology for advanced-generation batteries due to their high theoretical capacity and favorable redox potential. However, the practical integration of LMAs into high-energy rechargeable batteries is hindered by the challenge of Li dendrite growth. In this work, nanoparticles of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) loaded with Ce(OH)3 (LLZTCO) were designed and synthesized by a hydrothermal method. A functional composite separator was crafted by coating one side of a polypropylene (PP) separator with a composite electrolyte comprised of polyvinylidene fluoride (PVDF) and LLZTCO. The synergistic interactions between PVDF and LLZTCO provide numerous rapid lithium-ion (Li+) channels, facilitating the efficient redistribution of disparate Li+ flux originating from the insulated PP separator. The composite separator demonstrated an ionic conductivity (σ) of 3.68 × 10-3 S cm-1, substantial Li+ transference number (t+) of 0.73, and a high electrochemical window of 4.8 V at 25℃. Furthermore, the Li/LLZTCO@PP/Li symmetric cells demonstrated stable cycling for over 2000 h without significant dendrite formation. The Li/LiFePO4 (LFP) cells assembled with LLZTCO@PP separators exhibited a capacity retention of 91.6 % after 400 cycles at 1C. This study offers a practical approach to fabricating composite separators with enhanced safety and superior electrochemical performance.

Controlled three-dimensional leaf-like NiCoO2@NiCo layered double hydroxide heterostructures for oxygen evolution electrocatalysts in rechargeable Zn-air batteries.

Rechargeable zinc-air batteries (ZABs) have garnered attention as a viable choice for large-scale energy storage due to their advantageous characteristics, such as high energy density and cost-effectiveness. Strategies aimed at improving the kinetics of the oxygen evolution reaction (OER) through advanced electrocatalytic materials or structural designs can significantly enhance the efficiency and longevity of ZABs. In this study, we introduce a three-dimensional (3D) leaf-vein system heterojunction architecture. In this structure, NiCoO2 nanowire arrays form the central vein, surrounded by an outer leaf composed of NiCo layered double hydroxide (LDH) nanosheets. All these components are integrated onto a substrate made of Ni foam. Notably, when tested in an alkaline environment, the NiCoO2@NiCo LDH exhibited an overpotential of 272 mV at a current density of 10 mA cm-2, and extended durability evaluations over 12 h underscored its robustness at 99.76 %. The rechargeable ZABs achieved a peak power density of 149 mW cm-2. Furthermore, the NiCoO2@NiCo LDH demonstrated stability by maintaining high round-trip efficiencies throughout more than 680 cycles (equivalent to 340 h) under galvanostatic charge-discharge cycling at 5 mA cm-2. The leaf-vein system heterojunction significantly increased the active sites of the catalysts, facilitating charge transport, improving electronic conductivity, and enhancing overall stability.

Enhanced electrochemical performance in an aluminium doped δ-MnO2 supercapacitor cathode: experimental and theoretical investigations.

One of the biggest challenges faced by the layered manganese oxide MnO2 used as a supercapacitor cathode is the capacity fading caused by chemo-mechanical degradation and/or structural transformation occurring in the discharging/charging process. Here, based on systematical experimental measurements and theoretical calculations, we show that both the stability and rate performance of the δ-MnO2 supercapacitor cathode can be significantly enhanced by Al doping. Compared with pure δ-MnO2, Al doping (δ-Al0.06MnO2) clearly improves the specific capacitance (7% enhancement at 0.1 mA cm-2) and cycling stability (12% enhancement after 5000 cycles) simultaneously. These improvements can be attributed to the enhanced electronic transport and formation of more active sites, which are introduced by Al doping. Additionally, our calculations demonstrate that the doped systems (Al atoms located at Mn or O sites) show smaller surface energies than that of pure δ-MnO2, which hinders side reactions or structure transformations and leads to a better cycling lifetime. Our work gives a comprehensive understanding of the impacts on the performance of δ-MnO2 introduced by Al doping, and provides a feasible scheme to study the electrochemical mechanism of metal-doped δ-MnO2.

A Fast Charge/Discharge and Wide-Temperature Battery with a Germanium Oxide Layer on a Ti3C2 MXene Matrix as Anode.

A rapid charge/discharge secondary battery is critical in portable electronic devices and electric vehicles. Germanium, due to the metallic property and facile alloying reaction with lithium, displays great potential in fast charge/discharge batteries in contrast to other intercalation batteries. In order to accommodate the over 300% volume change, a 2D hybrid composite electrode consisting of a homogeneous, amorphous GeOx(x=1.57) layer bonded on Ti3C2 MXenes was successfully developed via an industry available method. The expanded interlayer space inside the MXene matrix accommodates the restricted isotropic expansion from the stress-released, ultrathin GeOx layer. Owing to the improved e-/Li+ conductivity from both metallic reduced Ge and MXene, the battery showed an excellent charge/discharge performance as fast as 3 min (20.0 C). A high-capacity retention of ∼1048.1 mAh/g along with a Coulombic efficiency (CE) of 99.8% at 0.5 C after 500 cycles was achieved. Under 1.0 C, the capacity was still up to 929.6 mAh/g with a CE of 99.6% (<0.02% capacity decay per cycle) after ultralong (1000) cycling. An almost doubled capacity of 671.6 mAh/g compared to graphite (372 mAh/g at 0.1 C) under 5.0 C and a capacity of 300.5 mAh/g under 10.0 C after 1000 cycles were respectively received. Under cold conditions, due to the low interface energy barrier, an efficient alloying reaction happens which prevents the Li plating on the electrode surface. High capacities of 631.6, 333.9, and 841.7 mAh/g under -20, -40, and 60 °C after 100 cycles demonstrate a wide temperature tolerance of the battery. In addition, a full-cell battery paired with LiNi0.8Mn0.1Co0.1O2 (NMC811) displayed a high capacity of 536.8 mAh/g after 200 cycles. A high capacity retention of a full pouch cell after 50 cycles was also obtained. The superhigh rate capability along with long cycling, wide temperature range, scalable production, and relatively low cost of this hybrid composite display promising potential in specific energy storage applications.