High-specific-power flexible transition metal dichalcogenide solar cells

Semiconducting transition metal dichalcogenides (TMDs) are promising for flexible high-specific-power photovoltaics due to their ultrahigh optical absorption coefficients, desirable band gaps and self-passivated surfaces. However, challenges such as Fermi-level pinning at the metal contact–TMD interface and the inapplicability of traditional doping schemes have prevented most TMD solar cells from exceeding 2% power conversion efficiency (PCE). In addition, fabrication on flexible substrates tends to contaminate or damage TMD interfaces, further reducing performance. Here, we address these fundamental issues by employing: (1) transparent graphene contacts to mitigate Fermi-level pinning, (2) MoOx capping for doping, passivation and anti-reflection, and (3) a clean, non-damaging direct transfer method to realize devices on lightweight flexible polyimide substrates. These lead to record PCE of 5.1% and record specific power of 4.4 W g−1 for flexible TMD (WSe2) solar cells, the latter on par with prevailing thin-film solar technologies cadmium telluride, copper indium gallium selenide, amorphous silicon and III-Vs. We further project that TMD solar cells could achieve specific power up to 46 W g−1, creating unprecedented opportunities in a broad range of industries from aerospace to wearable and implantable electronics.

Reliability and SOH Degradation of Thin Li-ion Batteries Under Various Flexing Conditions

Reliability of Li-ion batteries (LIB) is major concern for FHE devices due to needs of flexibility without degradation of state of health (SOH) of the LIB. In this regard, a thin form factor based LIB below 1mm of thickness is regarded as the candidate material to meet such needs because it is able to be fold, bent and twisted with limited performance drop. In addition to this, LIB has high specific power (W/Kg) and high specific energy (Wh/Kg) and a lower memory effect which could make the LIB more attractive for wearable applications. While studies on chemo-physical effect such as SEI growth, material decay, etc. due to repeated charging and discharging LIB has been conducted greatly, but such effects due to the flexing LIB have been rarely conducted. In this study, degradation of thin-flexible power source reliability has been studied under twist, flexing, flex-to-install of magnitude to replicate stresses of daily motion of human body using motion-control setups in a lab-environment. Additionally, AI-based regression model has been developed to predict the SOH of the battery with multiple variables including physical, ambient and chemo-mechanical experimental conditions which could be challenged to be treated by the manpower. The developed models can be used to predict the life of the battery and analyze acceleration factors between test conditions and use conditions for variety of test conditions based on the individual variables and their interactions.

Barriers and Challenges Going from Conventional to Cryogenic Superconducting Propulsion for Hybrid and All-Electric Aircrafts

The development of electric aircraft is becoming an important technology for achieving the goals set by the European Commission for the reduction of gases emissions by 2050 in the aeronautical transportation system. However, there is a technology gap between the current values of specific power in commercial electric machines and those required for aeronautical applications. Therefore, the search for alternative materials and non-conventional designs is mandatory. One emergent solution is using superconducting machines and systems to overcome the current limits of conventional electrical machines. This work reviews the new hybrid and all-electric aircraft tendencies, complementing it with recent research on the design and development of high specific power superconducting machines. This includes the main topologies for hybrid and all-electric aircraft, with an overview of the ongoing worldwide projects of these aircraft types, systematizing the main characteristics of their propulsion systems. It also includes the research on superconducting machines to achieve high specific power and consider the impact on the redesign of aircraft systems, the electrical, cooling, and fuel source systems.

Mechanism for Flexible Solar Cells

Flexible photovoltaics are covering the way to low-cost electricity. The build-up of organic, inorganic and organic–inorganic solar cells on flexible substrates by printing technologies is to provide lightweight and economic solar modules that can be incorporated in various surfaces. Progress of flexible and lightweight solar cell is interesting for many terrestrial and space applications that require a very high specific power. Thin-film solar cells on polymer films can produce more than 2KW\\Kg specific power. Flexible solar cells are proposed to open up a numerous of possibilities for enabling new applications in consumer electronics and space satellites. Recent research in thin-film electronics has been concentrated on the replacement of the traditional rigid glass plate substrate with plastic or metallic foils. Organic materials bear the potential to develop a long-term technology that is economically viable for large-scale power generation based on environmentally safe materials with unlimited availability. Organic and organic-inorganic photovoltaics (PVs) (third generation solar cells) continue to attract great attention from the PV community, due to their promising features such as low organic–inorganic cost, flexibility and light weight. In this chapter, many of the possible materials for manufacturing of flexible solar cells are discussed.

Barriers and Challenges Going From Conventional to Cryogenic Superconducting Propulsion for Hybrid and All-Electric Aircrafts

The development of electric aircrafts is becoming an important technology for achieving the goals set by the European Commission for the reduction of gases emissions by 2050 in the aeronautical transportation system. However, there is a gap between the values of specific power in commercial electric machines and the ones required for aeronautical applications. Therefore, the search for alternative materials and non-conventional designs is mandatory. One emergent solution is using superconducting machines and systems to overcome the current limits of conventional electrical machines. This work reviews the new hybrid and all-electric aircraft tendencies, complementing it with recent research on the design and development of high specific power superconducting machines. This includes the main topologies for hybrid and all-electric aircraft, with an overview of the ongoing worldwide projects of these types of aircrafts, systematizing the main characteristics of their propulsion systems. It also includes the research on superconducting machines for the purpose of high specific power, considering the impact on the redesign of aircraft systems in the electrical, cooling, and fuel source sense.

Physicochemical Approaches for Thin Film Energy Storage Devices through PVD Techniques

For the fabrication of thin films, Physical Vapor Deposition (PVD) techniques specified greater contribution than all other deposition techniques. Laser Ablation or Pulsed Laser deposition (PLD) technique is the one of most promising techniques for the fabrication of thin films among all other physical vapor deposition. In particular, flexible thin-film energy storage fabrication PLD plays an important role due to its special parameters such as fine thickness control, partial pressure atmospheric condition, pulsed repetition rate, in-situ annealing and microstructure optimization. Very recently, thin film supercapbatteries have been broadly studied, in which the battery and supercapacitor based electrodes are combined to obtain a high specific power and specific energy density and extended cycle stability. In order to fabricate thin film supercapbatteries, electrodes that have a large potential window, high capacitance, and capacity performance are vastly desired. Thus, the presented chapter represents an important enhancement in the growth of economical and eco-friendly thin flexible supercapbatteries and confirms their potential in sensible applications such as transport electronics devices and other gadgets.

An Insight into the Battery Degradation for a Proposal of a Battery Friendly Charging Technique

Li-ion batteries are widely used in electric vehicles because of their promising characteristics that meet high specific power and energy density requirements. The only setback is the capacity fading due to degradation in Li-ion batteries. The rate of capacity fade in Li-ion batteries in EVs vary based on the charging rate, changes in internal cell temperature and external ambient temperature, and user driving patterns. Since the Li-ion battery is electrochemical, determining the actual cause of degradation at a particular instant and constraining the rate is a big challenge. Further, the causes are related to parameters which are chemical, electrical and mechanical. In this work, the causes of degradation are studied by analysing the variation of parameters for multiple charge types and rates at different ambient temperatures. The analysis leads to developing a new universal charging scheme suitable to fast charge battery at different ambient temperatures appropriately and constrain battery degradation.

An Insight into the Battery Degradation and a Proposal for a Battery Friendly Charging Technique

Li-ion batteries are widely used in electric vehicles because of their promising characteristics that meet high specific power and energy density requirements. The only setback is the capacity fading due to degradation in Li-ion batteries. The rate of capacity fade in Li-ion batteries in EVs vary based on the charging rate, changes in internal cell temperature and external ambient temperature, and user driving patterns. Since the Li-ion battery is electrochemical, determining the actual cause of degradation at a particular instant and constraining the rate is a big challenge. Further, the causes are related to parameters which are chemical, electrical and mechanical. In this work, the causes of degradation are studied by analysing the variation of parameters for multiple charge types and rates at different ambient temperatures. The analysis leads to developing a new battery friendly charging scheme suitable to fast charge battery at different ambient temperatures appropriately and constrain battery degradation.