The solid-electrolyte interphase (SEI) critically governs the performance of rechargeable batteries. An ideal SEI is expected to be electrically insulative to prevent persistently parasitic reactions between the electrode and the electrolyte and ionically conductive to facilitate Faradaic reactions of the electrode. However, the true nature of the electrical properties of the SEI remains hitherto unclear due to the lack of a direct characterization method. Here we use in situ bias transmission electron microscopy to directly measure the electrical properties of SEIs formed on copper and lithium substrates. We reveal that SEIs show a voltage-dependent differential conductance. A higher rate of differential conductance induces a thicker SEI with an intricate topographic feature, leading to an inferior Coulombic efficiency and cycling stability in Li∣∣Cu and Li∣∣LiNiMnCoO cells. Our work provides insight into the targeted design of the SEI with desired characteristics towards better battery performance.

We explore how nuclear shut-downs in the United States could affect air pollution, climate and health with existing and alternative grid infrastructure. We develop a dispatch model to estimate emissions of CO, NO and SO from each electricity-generating unit, feeding these emissions into a chemical transport model to calculate effects on ground-level ozone and fine particulate matter (PM). Our scenario of removing nuclear power results in compensation by coal, gas and oil, resulting in increases in PM and ozone that lead to an extra 5,200 annual mortalities. Changes in CO emissions lead to an order of magnitude higher mortalities throughout the twenty-first century, incurring US$11-180 billion of damages from 1 year of emissions. A scenario exploring simultaneous closures of nuclear and coal plants redistributes health impacts and a scenario with increased penetration of renewables reduces health impacts. Inequities in exposure to pollution are persistent across all scenarios-Black or African American people are exposed to the highest relative levels of pollution.

Little is known about whether exposure to unconventional oil and gas development is associated with higher mortality risks in the elderly and whether related air pollutants are exposure pathways. We studied a cohort of 15,198,496 Medicare beneficiaries (136,215,059 person-years) in all major U.S. unconventional exploration regions from 2001 to 2015. We gathered data from records of more than 2.5 million oil and gas wells. For each beneficiary's ZIP code of residence and year in the cohort, we calculated a proximity-based and a downwind-based pollutant exposure. We analyzed the data using two methods: Cox proportional hazards model and Difference-in-Differences. We found evidence of statistically significant higher mortality risk associated with living in proximity to and downwind of unconventional oil and gas wells. Our results suggest that primary air pollutants sourced from unconventional oil and gas exploration can be a major exposure pathway with adverse health effects in the elderly.

Continuous-flow electrolyzers allow CO reduction at industrially relevant rates, but long-term operation is still challenging. One reason for this is the formation of precipitates in the porous cathode from the alkaline electrolyte and the CO feed. Here we show that while precipitate formation is detrimental for the long-term stability, the presence of alkali metal cations at the cathode improves performance. To overcome this contradiction, we develop an operando activation and regeneration process, where the cathode of a zero-gap electrolyzer cell is periodically infused with alkali cation-containing solutions. This enables deionized water-fed electrolyzers to operate at a CO reduction rate matching that of those using alkaline electrolytes (CO partial current density of 420 ± 50 mA cm for over 200 hours). We deconvolute the complex effects of activation and validate the concept with five different electrolytes and three different commercial membranes. Finally, we demonstrate the scalability of this approach on a multi-cell electrolyzer stack, with a 100 cm / cell active area.

Hydropower emits less carbon dioxide than fossil fuels but the lower albedo of hydropower reservoirs compared to terrestrial landscapes results in a positive radiative forcing offsetting some of the negative radiative forcing by hydroelectricity generation. The cumulative effect of this lower albedo has not been quantified. Here we show, by quantifying the difference in remotely sensed albedo between globally distributed hydropower reservoirs and their surrounding landscape, that 19 % of all investigated hydropower plants required 40 years and more for the negative radiative forcing from the fossil fuel displacement to offset the albedo effect. The length of these break-even times depends on the specific combination of climatic and environmental constraints, power plant design characteristics and country-specific electricity carbon intensities. We conclude that future hydropower plants need to minimize the albedo penalty in order to make a meaningful contribution towards limiting global warming.

Like many cities around the world, New York City is establishing policies to reduce CO emissions from all energy sectors by 2050. Understanding the impact of varying degrees of electric vehicle adoption and CO intensities on emissions reduction in the city is critical. Here, using a technology-rich, bottom-up, energy system optimization model, we analyse the cost and air emissions impacts of New York City's proposed CO reduction policies for the transportation sector through a scenario framework. Our analysis reveals that the electrification of light-duty vehicles at earlier periods is essential for deeper reductions in air emissions. When further combined with energy efficiency improvements, these actions contribute to CO reductions under the scenarios of more CO-intense electricity. Substantial reliance on fossil fuels and a need for structural change pose challenges to cost-effective CO reductions in the transportation sector. Here we find that uncertainties associated with decarbonization of the electric grid have a minimum influence on the cost-effectiveness of CO reduction pathways for the transportation sector.

Semi-transparent photovoltaics only allows for the fabrication of solar cells with an optical transmission that is fixed during their manufacturing resulting in a trade-off between transparency and efficiency. For the integration of semi-transparent devices in building, ideally solar cells should generate electricity while offering the comfort for users to self-adjust their light transmission with the intensity of the daylight. Here we report a photochromic dye-sensitized solar cell (DSSC) based on donor-π-conjugated bridge-acceptor structures where the π-conjugated bridge is substituted for a diphenyl-naphthopyran photochromic unit. DSSCs show change in colour and self-adjustable light transmittance when irradiated with visible light and a power conversion efficiency up to 4.17%. The colouration-decolouration process is reversible and these DSSCs are stable over 50 days. We also report semi-transparent photo-chromo-voltaic mini-modules (23 cm) exhibiting a maximum power output of 32.5 mW after colouration.

Ninety-five per cent of Indian households now have access to liquified petroleum gas (LPG), with 80 million acquiring it under the (PMUY) since 2016. Still, having a connection is not enough to eliminate household air pollution. Studying panel data from rural households in six major states from 2014-2015 and 2018, we assess the determinants of cooking energy transition from solid fuels to LPG. We find that PMUY beneficiaries have much lower odds of using LPG as the primary or exclusive fuel compared with general customers, irrespective of their economic status. Village-level penetration of LPG as a primary fuel and the years of LPG use positively influence its sustained use, while ease of access to freely available biomass and reliance on uncertain and irregular income sources hinder LPG use. The findings highlight the need to interlace cooking fuel policies with rural development, to enable a complete transition towards cleaner cooking fuels.

Coal-fired power plants release substantial air pollution, including over 60% of U.S. sulfur dioxide (SO) emissions in 2014. Such air pollution may exacerbate asthma however direct studies of health impacts linked to power plant air pollution are rare. Here, we take advantage of a natural experiment in Louisville, Kentucky, where one coal-fired power plant retired and converted to natural gas, and three others installed SO emission control systems between 2013 and 2016. Dispersion modeling indicated exposure to SO emissions from these power plants decreased after the energy transitions. We used several analysis strategies, including difference-in-differences, first-difference, and interrupted time-series modeling to show that the emissions control installations and plant retirements were associated with reduced asthma disease burden related to ZIP code-level hospitalizations and emergency room visits, and individual-level medication use as measured by digital medication sensors.

Polymer donors and non-fullerene acceptors have played an important role as photoactive materials in the development of high-efficiency organic solar cells and have immense potential in devices for direct solar hydrogen generation. However, their use in direct solar water-splitting devices has been limited by their instability in aqueous environment and recombination losses at the interface with catalysts. Here we report anodes containing PM6:D18:L8-BO photoactive layers reaching high solar water oxidation photocurrent density over 25 mA cm at +1.23 V versus reversible hydrogen electrode and days-long operational stability. This was achieved by integrating the organic photoactive layer with a graphite sheet functionalized with earth-abundant NiFeOOH water oxidation catalyst, which provides both water resistance and electrical connection between the catalyst and the photoactive layer without any losses. Using monolithic tandem anodes containing organic PM6:D18:L8-BO and PTQ10:GS-ISO photoactive layers, we achieve a solar-to-hydrogen efficiency of 5%. These results pave the way towards high-efficiency, stable and unassisted solar hydrogen generation by low-cost organic photoactive materials.

Lithium metal batteries (LMBs) hold the promise to pushing cell level energy densities beyond 300 Wh kg while operating at ultra-low temperatures (< -30°C). Batteries capable of both charging and discharging at these temperature extremes are highly desirable due to their inherent reduction of external warming requirements. Here we demonstrate that the local solvation structure of the electrolyte defines the charge-transfer behavior at ultra-low temperature, which is crucial for achieving high Li metal coulombic efficiency (CE) and avoiding dendritic growth. These insights were applied to Li metal full cells, where a high-loading 3.5 mAh cm sulfurized polyacrylonitrile (SPAN) cathode was paired with a one-fold excess Li metal anode. The cell retained 84 % and 76 % of its room temperature capacity when cycled at -40 and -60 °C, respectively, which presented stable performance over 50 cycles. This work provides design criteria for ultra-low temperature LMB electrolytes, and represents a defining step for the performance of low-temperature batteries.

[This corrects the article DOI: 10.1038/s41560-020-0662-1.].

Electric vehicles are increasingly being adopted in Great Britain and other parts of the world, driven by the perception that they offer a cost-effective alternative to internal combustion engine vehicles while reducing emissions. However, a key element that underpins this perception is the longevity of electric vehicles, which remains relatively under researched. Here we show that although early battery electric vehicles (BEVs) exhibited lower reliability than internal combustion engine vehicles, rapid technological advancements have allowed newer BEVs to achieve comparable lifespans, even under more intensive use. Longevity is also found to be impacted by engine size, location and make of vehicle. We provide parameter estimates for life mileage that can be used to update life cycle assessment and total cost of ownership studies of different vehicle powertrains. Our results also shed light on BEV diffusion patterns, fleet replacement strategies and end-of-life treatment planning, including the increasingly important debate around BEV battery recycling and second-life options.

Integrated assessment and energy system models are challenged to account for societal transformation dynamics, but empirical evidence is lacking on which factors to incorporate, how and to what extent this would improve the relevance of modelled pathways. Here we include six societal factors related to infrastructure dynamics, actors and decision-making, and social and institutional context into an open-source simulation model of the national power system transition. We apply this model in 31 European countries and, using hindcasting (1990-2019), quantify which societal factors improved the modelled pathways. We find that, if well-chosen and in most cases, incorporating societal factors can improve the hindcasting performance by up to 27% for modelled installed capacity of individual technologies. Public acceptance, investment risks and infrastructure lockin contribute the most to model performance improvement. Our study paves the way to a systematic and objective selection of societal factors to be included in energy transition modelling.

Electrochemical reduction of CO (CORR) to multi-carbon products is a promising technology to store intermittent renewable electricity into high-added-value chemicals and close the carbon cycle. Its industrial scalability requires electrocatalysts to be highly selective to certain products, such as ethylene or ethanol. However, a substantial knowledge gap prevents the design of tailor-made materials, as the properties ruling the catalyst selectivity remain elusive. Here we combined in situ surface-enhanced Raman spectroscopy and density functional theory on Cu electrocatalysts to unveil the reaction scheme for CORR to C products. Ethylene generation occurs when *OC-CO(H) dimers form via CO coupling on undercoordinated Cu sites. The ethanol route opens up only in the presence of highly compressed and distorted Cu domains with deep -band states via the crucial intermediate *OCHCH. By identifying and tracking the critical intermediates and specific active sites, our work provides guidelines to selectively decouple ethylene and ethanol production on rationally designed catalysts.

Microscopy provides a proxy for assessing the operation of perovskite solar cells, yet most works in the literature have focused on bare perovskite thin films, missing charge transport and recombination losses present in full devices. Here we demonstrate a multimodal operando microscopy toolkit to measure and spatially correlate nanoscale charge transport losses, recombination losses and chemical composition. By applying this toolkit to the same scan areas of state-of-the-art, alloyed perovskite cells before and after extended operation, we show that devices with the highest macroscopic performance have the lowest initial performance spatial heterogeneity-a crucial link that is missed in conventional microscopy. We show that engineering stable interfaces is critical to achieving robust devices. Once the interfaces are stabilized, we show that compositional engineering to homogenize charge extraction and to minimize variations in local power conversion efficiency is critical to improve performance and stability. We find that in our device space, perovskites can tolerate spatial disorder in chemistry, but not charge extraction.

The European Union's plan to phase out Russian natural gas imports by 2027 rests partly on increasing near-term imports of US liquefied natural gas. This will require a coordinated policy response that includes securing supplies from major exporters, global diplomacy, expanding import capacity, and alignment with Europe's climate goals.

Direct air capture is an emerging technology to decrease atmospheric CO levels, but it is currently costly and the long-term consequences of CO storage are uncertain. An alternative approach is to utilize atmospheric CO on-site to produce value-added renewable fuels, but current CO utilization technologies predominantly require a concentrated CO feed or high temperature. Here we report a gas-phase dual-bed direct air carbon capture and utilization flow reactor that produces syngas (CO + H) through on-site utilization of air-captured CO using light without requiring high temperature or pressure. The reactor consists of a bed of solid silica-amine adsorbent to capture aerobic CO and produce CO-free air; concentrated light is used to release the captured CO and convert it to syngas over a bed of a silica/alumina-titania-cobalt bis(terpyridine) molecular-semiconductor photocatalyst. We use the oxidation of depolymerized poly(ethylene terephthalate) plastics as the counter-reaction. We envision this technology to operate in a diurnal fashion where CO is captured during night-time and converted to syngas under concentrated sunlight during the day.

Climate stabilization requires the mobilization of substantial investments in low- and zero-carbon technologies, especially in emerging and developing economies. However, access to stable and affordable finance varies dramatically across countries. Models used to evaluate the energy transition do not differentiate regional financing costs and therefore cannot study risk-sharing mechanisms for renewable electricity generation. In this study, we incorporated the empirically estimated cost of capital differentiated by country and technology into an ensemble of five climate-energy-economy models. We quantified the additional financing cost of decarbonization borne by developing regions and explored policies of risk premium convergence across countries. We found that alleviating financial constraints benefits both climate and equity as a result of more renewable and affordable energy in the developing world. This highlights the importance of fair finance for energy availability, affordability and sustainability, as well as the need to include financial considerations in model-based assessments.

The stabilization of grain boundaries and surfaces of the perovskite layer is critical to extend the durability of perovskite solar cells. Here we introduced a sulfonium-based molecule, dimethylphenethylsulfonium iodide (DMPESI), for the post-deposition treatment of formamidinium lead iodide perovskite films. The treated films show improved stability upon light soaking and remains in the black phase after two years ageing under ambient condition without encapsulation. The DMPESI-treated perovskite solar cells show less than 1% performance loss after more than 4,500 h at maximum power point tracking, yielding a theoretical of over nine years under continuous 1-sun illumination. The solar cells also display less than 5% power conversion efficiency drops under various ageing conditions, including 100 thermal cycles between 25 °C and 85 °C and an 1,050-h damp heat test.

Separation processes are substantially more difficult when the species to be separated is highly dilute. To perform any dilute separation, thermodynamic and kinetic limitations must be overcome. Here we report a molten-carbonate membrane that can 'pump' CO from a 400 ppm input stream (representative of air) to an output stream with a higher concentration of CO, by exploiting ambient energy in the form of a humidity difference. The substantial HO concentration difference across the membrane drives CO permeation 'uphill' against its own concentration difference, analogous to active transport in biological membranes. The introduction of this HO concentration difference also results in a kinetic enhancement that boosts the CO flux by an order of magnitude even as the CO input stream concentration is decreased by three orders of magnitude from 50% to 400 ppm. Computational modelling shows that this enhancement is due to the HO-mediated formation of carriers within the molten salt that facilitate rapid CO transport.