News & Views in 2016

Tin-based perovskite solar cells are less toxic than their lead-based counterparts, but suffer from severe stability issues due to the susceptibility of tin to oxidation. Now, a CsSnI₃ perovskite solar cell with a SnCl₂ additive is shown to exhibit remarkable stability.

The US Clean Power Plan establishes detailed CO₂ emissions reductions targets at state level with a flexible framework for implementation. This flexibility is intended to spur innovation and economic efficiency, but a study finds that it creates vast uncertainties around both the implementation of the rule and subsequent impacts.

Catalysing the oxygen evolution reaction is central to electrochemical energy conversion technologies such as electrolysis, but the high cost of state-of-the-art precious metal oxide electrocatalysts hinders commercialization. Now, thin sheets of a metal–organic framework are shown to provide a high-performing, cheaper alternative.

Concentrated thermoelectric generators convert solar energy to electricity, but historically their conversion efficiency has lagged behind their potential. Now, full system efficiencies of 7.4% are achieved by segmentation of two thermoelectric materials and a spectrally selective surface.

Nanostructured metallic crystals are already used to catalyse energy conversions, such as those that occur in fuel cells. However, to design improved materials, a deeper understanding of nanocrystal growth is required. Now, details of the mechanisms underpinning the synthesis of highly active, bimetallic Pt–Ni electrocatalysts are elucidated.

The degradation and failure of Li-ion batteries is strongly associated with electrode microstructure change upon (de)lithiation. Now, an operando X-ray tomography approach is shown to correlate changes in the microstructure of electrodes to cell performance, and thereby predict degradation pathways.

Energy access entails a range of metrics that need to be monitored to guide planning and implementation of electricity provision in developing nations. A study based on an extensive household survey carried out in rural India demonstrates that electricity supply duration is the best predictor for satisfaction with electricity service.

The energy output of aqueous batteries is largely limited by the narrow voltage window of their electrolytes. Now, a hydrate melt consisting of lithium salts is shown to expand such voltage windows, leading to a high-energy aqueous battery.

The elastocaloric effect can be exploited in solid-state cooling technologies as an alternative to conventional vapour compression. Now, an elastocaloric device based on the concept of active regeneration achieves a temperature lift of 15.3 K and efficiencies competitive with other caloric-based approaches.

Political divisions are important in understanding public perceptions of unconventional oil and natural gas development, but so is proximity to drilling activities. New research highlights that, as geographical distance from development areas increases, political ideology becomes more influential in explaining diverging perceptions.

Lower-cost alternatives to platinum electrocatalysts are being explored for the sustainable production of hydrogen, but often trial-and-error approaches are used for their development. Now, principles are elucidated that suggest pathways to rationally design efficient metal-free electrocatalysts based on doped graphene.

Increasing the penetration of distributed generation and smart grid technologies requires substantial investments. A study proposes an innovative approach that combines four regulatory tools to provide economic incentives for distribution system operators to facilitate these innovative practices.

Fuel cells typically function well only in rather limited temperature and humidity ranges. Now, a proton exchange membrane consisting of ion pair complexes is shown to enable improved fuel cell performance under a wide range of conditions that are unattainable with conventional approaches.

The solar-driven generation of water steam at 100 °C under one sun normally requires the use of optical concentrators to provide the necessary energy flux. Now, thermal concentration is used to raise the vapour temperature to 100 °C without the need for costly optical concentrators.

For uptake of electric vehicles to increase, consumers' driving-range needs must be fulfilled. Analysis of the driving patterns of personal vehicles in the US now shows that today's electric vehicles can meet all travel needs on almost 90% of days from a single overnight charge.

Electricity distribution system planners rely on estimations of future energy demand to build adequate supply, but these are complicated to achieve. An approach that combines spatially resolved projections of population movement and climate change offers a method for building better demand maps to mid-century.

In the development of lithium–air batteries, managing the phase change between gaseous oxygen and crystalline lithium peroxide is a key challenge. Now, a high-performing sealed battery with an oxygen anion-redox electrode is presented that does not involve any gas evolution.

Energy-saving programmes are increasingly targeted at children to encourage household energy conservation. A study involving the assignment of energy-saving interventions to Girl Scouts shows that a child-focused intervention can improve energy-saving behaviours among children and their parents.

The electronic properties of halide perovskites vary significantly between crystalline grains, but the impact of this heterogeneity on solar cell performance is unclear. Now, this variability is shown to limit the photovoltaic properties of solar cells, and its origins are linked to differing properties between crystal facets.

The major obstacle in the development of Li–S batteries is the undesired dissolution of polysulfide intermediates produced during electrochemical reactions. Now, a metal–organic framework-based separator is shown to mitigate the problem, leading to stable long cycles.