Ultralow Resistance Two-Stage Electrostatically Assisted Air Filtration by Polydopamine Coated PET Coarse Filter.

Airborne particulate matters (PM) pose serious health threats to the population, and efficient filtration is needed for indoor and vehicular environments. However, there is an intrinsic conflict between filtration efficiency, air resistance, and service life. In this study, a two-stage electrostatically assisted air (EAA) filtration device is designed and the efficiency-air resistance-filter life envelope is significantly improved by a thin coating of polydopamine (PDA) on the polyethylene terephthalate (PET) coarse filter by in situ dopamine polymerization. The 8 mm thick EAA PDA-140@PET filter has a high filtration efficiency of 99.48% for 0.3 µm particles, low air resistance of 9.5 Pa at a filtration velocity of 0.4 m s-1 , and steady performance up to 30 d. Compared with the bare PET filter, the penetration rate for 0.3 µm particles is lowered by 20×. The coated PDA is of submicron thickness, 10-3  × the gap distance between filter fibers, so low air resistance could be maintained. The filter shows steadily high filtration efficiency and an acceptable increase of air resistance and holds nearly as many particles as its own weight in a 30 day long-term test. The working mechanism of the EAA coarse filter is investigated, and the materials design criteria are proposed.

Sacrificial Poly(propylene carbonate) Membrane for Dispersing Nanoparticles and Preparing Artificial Solid Electrolyte Interphase on Li Metal Anode.

Lithium-metal batteries have been regarded as next-generation high-energy-density candidates beyond lithium-ion batteries. However, the lithium-morphology instabilities accompanied by continuous side reactions with electrolytes inevitably leads to dissatisfactory performances and even safety issues, where the unstable interface between lithium-metal anode and electrolytes has been regarded as the root cause. Artificial solid electrolyte interphase engineering has attracted a lot of attention to stabilize lithium-metal anodes. Here, a novel method with universality is reported to produce the organic-inorganic artificial solid electrolyte interphase. Using poly(propylene carbonate) as a sacrificial matrix, nanoparticles are dispersed on lithium-metal anodes surface uniformly to prepare artificial solid electrolyte interphase, where poly(propylene carbonate) turns into liquid propylene carbonate upon contact with lithium-metal anode. Silicon, Li1.5Al0.5Ge1.5(PO4)3, or Li1.4Al0.4Ti1.6(PO4)3 nanoparticles are coated to suppress lithium-morphology instabilities and demonstrated ∼4 times longer cycle life. Preparing various organic/inorganic artificial solid electrolyte interphase is feasible by introducing various components in the fabrication process of poly(propylene carbonate) membrane, endowing this approach with huge potential in the research of artificial solid electrolyte interphase.

A Surface Se-Substituted LiCo[O2- δ Seδ ] Cathode with Ultrastable High-Voltage Cycling in Pouch Full-Cells.

Cycling LiCoO2 to above 4.5 V for higher capacity is enticing; however, hybrid O anion- and Co cation-redox (HACR) at high voltages facilitates intrinsic Oα - (α < 2) migration, causing oxygen loss, phase collapse, and electrolyte decomposition that severely degrade the battery cyclability. Hereby, commercial LiCoO2 particles are operando treated with selenium, a well-known anti-aging element to capture oxygen-radicals in the human body, showing an "anti-aging" effect in high-voltage battery cycling and successfully stopping the escape of oxygen from LiCoO2 even when the cathode is cycled to 4.62 V. Ab initio calculation and soft X-ray absorption spectroscopy analysis suggest that during deep charging, the precoated Se will initially substitute some mobile Oα - at the charged LiCoO2 surface, transplanting the pumped charges from Oα - and reducing it back to O2- to stabilize the oxygen lattice in prolonged cycling. As a result, the material retains 80% and 77% of its capacity after 450 and 550 cycles under 100 mA g-1 in 4.57 V pouch full-cells matched with a graphite anode and an ultralean electrolyte (2 g Ah-1 ).

Constructing Effective Interfaces for Li1.5Al0.5Ge1.5(PO4)3 Pellets To Achieve Room-Temperature Hybrid Solid-State Lithium Metal Batteries.

Solid electrolytes are considered as strong alternatives for conventional liquid electrolytes to overcome the safety issues of next-generation high-energy-density lithium metal batteries (LMBs). Although Li1.5Al0.5Ge1.5(PO4)3 (LAGP) has satisfied ionic conductivity at room temperature (∼10-4 S cm-1), high stability in air, and can be easily sintered, it still suffers from instability of the lithium metal. Moreover, the large interfacial resistance between solid electrolytes and solid electrodes and the stress generated by the volumetric change of lithium metal anodes during cycling would deteriorate the performance of LMBs. Here, we report an effective solution to overcome the abovementioned problems by introducing a three-dimensional gel polymer electrolyte at the interface between LAGP pellets and lithium metal anodes, achieving stable cycling of LiFePO4//Li cells at room temperature for 300 cycles. Besides, the degeneration mechanisms of the interfaces of LAGP pellets under different conditions are compared, and peculiar properties different from their counterparts were found.

Review of Recent Development of In Situ/Operando Characterization Techniques for Lithium Battery Research.

The increasing demands of energy storage require the significant improvement of current Li-ion battery electrode materials and the development of advanced electrode materials. Thus, it is necessary to gain an in-depth understanding of the reaction processes, degradation mechanism, and thermal decomposition mechanisms under realistic operation conditions. This understanding can be obtained by in situ/operando characterization techniques, which provide information on the structure evolution, redox mechanism, solid-electrolyte interphase (SEI) formation, side reactions, and Li-ion transport properties under operating conditions. Here, the recent developments in the in situ/operando techniques employed for the investigation of the structural stability, dynamic properties, chemical environment changes, and morphological evolution are described and summarized. The experimental approaches reviewed here include X-ray, electron, neutron, optical, and scanning probes. The experimental methods and operating principles, especially the in situ cell designs, are described in detail. Representative studies of the in situ/operando techniques are summarized, and finally the major current challenges and future opportunities are discussed. Several important battery challenges are likely to benefit from these in situ/operando techniques, including the inhomogeneous reactions of high-energy-density cathodes, the development of safe and reversible Li metal plating, and the development of stable SEI.

Cross-linked beta alumina nanowires with compact gel polymer electrolyte coating for ultra-stable sodium metal battery.

Sodium metal batteries have potentially high energy densities, but severe sodium-dendrite growth and side reactions prevent their practical applications, especially at high temperatures. Herein, we design an inorganic ionic conductor/gel polymer electrolyte composite, where uniformly cross-linked beta alumina nanowires are compactly coated by a poly(vinylidene fluoride-co-hexafluoropropylene)-based gel polymer electrolyte through their strong molecular interactions. These  beta alumina nanowires combined with the gel polymer layer create dense and homogeneous solid-liquid hybrid sodium-ion transportation channels through and along the nanowires, which promote uniform sodium deposition and formation of a stable and flat solid electrolyte interface on the sodium metal anode. Side reactions between the sodium metal and liquid electrolyte, as well as sodium dendrite formation, are successfully suppressed, especially at 60 °C. The sodium vanadium phosphate/sodium full cells with composite electrolyte exhibit 95.3% and 78.8% capacity retention after 1000 cycles at 1 C at 25 °C and 60 °C, respectively.

Dendrite-Free, High-Rate, Long-Life Lithium Metal Batteries with a 3D Cross-Linked Network Polymer Electrolyte.

A 3D network gel polymer electrolyte (3D-GPE) is designed for lithium metal batteries and prepared by an initiator-free one-pot ring-opening polymerization technique. This 3D-GPE exhibits an unprecedented combination of mechanical strength, ionic conductivity, and more importantly, effective suppression of Li dendrite growth. The produced lithium-based battery presents long life, high rate, and excellent safety.