Nitrous acid (HONO) is an important component of indoor air as a photolabile precursor to hydroxyl radicals and has direct health effects. HONO concentrations are typically higher indoors than outdoors, although indoor concentrations have proved challenging to predict using box models. In this study, time-resolved measurements of HONO and NO2 in a residence showed that [HONO] varied relatively weakly over contiguous periods of hours, while [NO2] fluctuated in association with changes in outdoor [NO2]. Perturbation experiments were performed in which indoor HONO was depleted or elevated and were interpreted using a two-compartment box model. To reproduce the measurements, [HONO] had to be predicted using persistent source and sink processes that do not directly involve NO2, suggesting that HONO was in equilibrium with indoor surfaces. Production of gas phase HONO directly from conversion of NO2 on surfaces had a weak influence on indoor [HONO] during the time of the perturbations. Highly similar temporal responses of HONO and semivolatile carboxylic acids to ventilation of the residence along with the detection of nitrite on indoor surfaces support the concept that indoor HONO mixing ratios are controlled strongly by gas-surface equilibrium.

The need for better battery materials has driven research into underexplored complex phase spaces. Herein, we perform the first high-throughput electrochemical study of the entire Li–Ni–Mn–O system of interest for next-generation high-energy cathodes. We first adapt a high-throughput electrochemical system to cycle 64 mg-scale cathodes simultaneously and demonstrate its effectiveness with two test materials: LiCoO2 and Li­[Ni1/3Mn1/3Co1/3]­O2. The average values for the electrochemical properties obtained for the combinatorial samples show excellent agreement with literature, and cell-to-cell reproducibility is about 7%. The results for the Li–Ni–Mn–O system deepens our understanding dramatically and will guide the rational design of high-energy cathodes.

Lithium-ion batteries have achieved commercial success; however, work remains to increase the capacity and safety of both the anode and cathode electrodes. Organic anodes have the potential to replace conventional graphite anodes because they are abundant, safe, and high-capacity materials. Superlithiated organic anodes achieve capacities in excess of 1500 mA h g–1; however, the mechanism of superlithiation and how it relates to different materials is an open question. Here, we disclose a pyrene-fused azaacene polymer that undergoes superlithiation and exhibits a continuous activation process, whereby the capacity increases with the number of cycles, reaching values up to 1775 mA h g–1 (1535 mA h g–1, subtracting the carbon additive contribution). This high performance is attributed to the stability and extended conjugation afforded by the polymer design. Ex situ studies suggest cycling results in deformation of the electrode structure, from an amorphous electrode material to one with increased crystallinity and sp2 character. Importantly, this superlithiated electrode maintains the same capacity across a 10-fold increase in rate during the activation process, showing that the kinetic limitations of superlithiation can be overcome and suggesting that commercial practical superlithiation anodes are within reach.

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Pseudocapacitive polymers offer potential for higher energy densities than electrostatic double-layer capacitive materials and lower cost than pseudocapacitive metal oxides. These polymers typically demonstrate good stability when storing positive charges but poor stability when storing negative charges. The power and energy densities of these materials are also limited when the operating voltage window is restricted to positive voltages. The development of polymers capable of stable positive and negative charge storage is necessary to allow a wider voltage window and create high performance polymer supercapacitors. Here, we present a poly­(3,4-ethylenedioxythiophene)-pendant tetrachlorinated perylene diimide polymer capable of storing positive and negative charges, which utilizes a donor–node–acceptor architecture to prevent electronic interactions between positive and negative charge storing units. The polymer films show balanced charge storage and excellent stability in both positive and negative charge storage, retaining more than 80% of their capacitance over 1000 cycles. The films demonstrate moderate capacitances of 78.6 F g–1 in the positive region and 73.1 F g–1 in the negative region at 0.5 A g–1, as well as excellent rate capabilities in positive and negative charge storage regions of 87 and 56% at 20 A g–1, respectively. The polymer film was applied as both electrodes in a symmetric type III supercapacitor device with a gel polymer electrolyte, demonstrating a wide operating potential range of 2.2 V. These results demonstrate that the cycling stability of ambipolar polymers can be improved using a donor–node–acceptor polymer architecture with an extended π-conjugated donor unit.