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A structure-level smart deployable truss (SDT) was further studied for on-orbit verification on the SJ18 Geostationary Satellite in this work on the basis of a material-level validation of a shape-memory polymer composite (SMPC) sheet on the SJ17 Geostationary Satellite in 2016. In the SDT, a shape-memory alloy (SMA) mechanism was used to replace traditional pyrotechnic devices for locking and releasing, and SMPC actuation laminates were employed to replace traditional motor or spring driving mechanisms. With a strict parameter constrain of mass, size, and stiffness, the current form of the SDT flight hardware was finally obtained through several cycles of optimization design. Its systematical ground-based experiments were conducted, and the overall structural and functional performance met the demands of the aerospace standards of China. The locking force and expansion breaking force of the SMA releasing mechanism were [Formula: see text] and [Formula: see text], ensuring the locking and unlocking reliability for the movable parts with mass 5 kg. The actuation force of all SMPC laminates decreased from [Formula: see text] (0°) to [Formula: see text] (165°) with a recovery duration of [Formula: see text], which was strong enough for SDT deployment in space. The shape-memory materials show great prospects for smart deployable structures in space.

Sulfonated graphene oxide (SGO) is already utilized as an effective filler in proton exchange membranes (PEMs) for performance enhancement in direct methanol fuel cells (DMFCs). Previously, SGO has been mostly prepared via functionalization based on the intrinsic groups of graphene oxide (GO), which may cause inhomogeneity/insufficient sulfonation and possibly limit the improvement of membrane performance. To overcome this widely overlooked problem, herein, a new type of GO sulfonation product, SDGO, is fabricated by carrying out the sulfonation on polydopamine (PDA) deposited GO, which results in improved uniformity/sufficient sulfonation on SDGO compared to PDA-free SGO. Therefore, the sulfonated poly(ether ether ketone) (SPEEK) composite PEMs filled with SDGO show better matrix–filler compatibility, larger hydrophilic domains and less voids than those using PDA-free SGO, which lead to much improved proton conductivity, methanol barrier and mechanical properties. SPEEK–SDGO based DMFCs largely outperform Nafion 212 based DMFCs, achieving an output of 177.93 mW cm−2 (80 °C, 1 M methanol/O2), one of the most competitive DMFC power densities reported for DMFCs based on SGO composite membranes. Moreover, the radical scavenging ability of PDA boosts the stability of SPEEK–SDGO composite membranes in chemical accelerated stress tests. Mechanical accelerated stress tests and constant voltage experiments further confirm the superior durability of SPEEK–SDGO composite membranes during DMFC operations.

Mars is believed to contain signs of the ancient life and to be the future of humankind. Deep space explorations on Mars have received extensive attention from the scientific and engineering communities. An ancient papyrus scroll-inspired mechanism to deploy the national flag after landing is proposed in this paper. Firstly, a papyrus scroll-inspired structure folded and deployed by shape memory polymer composites (SMPCs) was designed. The material was characterised by both thermodynamic analysis and static mechanical tests. Then, computational modal analysis was completed with material parameters at 25 °C, 55 °C and 85 °C to investigate the temperature effect. Besides, ground-based engineering validations were conducted, including vibration, shock and acceleration tests, as well as deployment verification. Natural frequencies obtained from vibration agreed well with that calculated from simulation. Regular and vacuum deployments showed differences but were both acceptable. Additionally, release reliability greater than 99.99% was obtained through repeated experimental data. Finally, on-Mars qualification was completed with China’s Tianwen-1 mission, with images of the deployed five-star red flag transmitted by the Zhurong rover. It is the world’s first validation of self-deployable mechanism based on SMPCs in deep space, and further applications can be expected.

Phosphotungstic acid (HPW)-filled composite proton exchange membranes possess high proton conductivity under low relative humidity (RH). However, the leaching of HPW limits their wide application. Herein, we propose a novel approach for anchoring water soluble phosphotungstic acid (HPW) by polydopamine (PDA) coated graphene oxide and halloysite nanotubes (DGO and DHNTs) in order to construct hybrid three-dimensional proton transport networks in a sulfonated poly(ether ether ketone) (SPEEK) membrane. The introduction of PDA on the surfaces of the hybrid fillers could provide hydroxyl groups and secondary amine groups to anchor HPW, resulting in the uniform dispersion of HPW in the SPEEK matrix. The SPEEK/DGO/DHNTs/HPW (90/5/5/60) composite membrane exhibited higher water uptake and much better conductivity than the SPEEK membrane at low relative humidity. The best conductivity reached wass 0.062 S cm−1 for the composite membrane, which is quite stable during the water immersion test.

In this work, sulfonated poly(ether ether ketone) (SPEEK) nanocomposite membranes were prepared with high loading of phosphotungstic acid (HPW) immobilized by polydopamine coated halloysite nanotubes (DHNTs). XPS and FTIR analysis revealed the formation of acid-base interactions between HPW and DHNTs in the nanocomposite membranes, indicating the successful immobilization of HPW on the surface of high aspect-ratio DHNTs, which helped shorten the distance of proton hopping and create more continuous proton transport pathways along the high aspect-ratio nanotubes. The activation energy for the proton transfer in the nanocomposite membranes was greatly reduced and membrane proton conductivity was significantly enhanced. Compared with the SPEEK control membrane, the nanocomposite membrane with 42.9 wt% HPW loading achieved 114% increase in proton conductivity, up from 0.048 S cm−1 to 0.117 S cm−1, and the membrane water uptake remained almost the same. Under the long term water immersion test, the SPEEK/DHNTs/HPW nanocomposite membrane exhibited much slower decrease in proton conductivity than the SPEEK/HPW membrane without DHNTs, indicating the strong HPW-binding effect from DHNTs on slowing down the leakage of HPW.

The rechargeable magnesium (Mg) battery has been considered a promising candidate for future battery generations due to unique advantages of the Mg metal anode. The combination of Mg with a sulfur cathode is one of the attractive electrochemical energy storage systems that use safe, low-cost, and sustainable materials and could potentially provide a high energy density. To develop a suitable electrolyte remains the key challenge for realization of a magnesium sulfur (Mg–S) battery. Herein, we demonstrate that magnesium tetrakis(hexafluoroisopropyloxy) borate Mg[B(hfip)4]2 (hfip = OC(H)(CF3)2) satisfies a multitude of requirements for an efficient and practical electrolyte, including high anodic stability (>4.5 V), high ionic conductivity (∼11 mS cm–1), and excellent long-term Mg cycling stability with a low polarization. Insightful mechanistic studies verify the reversible redox processes of Mg–S chemistry by utilizing Mg[B(hfip)4]2 electroylte and also unveil the origin of the voltage hysteresis in Mg–S ...

It is of great importance to improve the proton conductivity of proton exchange membranes by easy-handling and cost-efficient approaches. In this work, we incorporated a commercially obtained surfactant, sodium dodecyl benzene sulfonate (SDBS), into sulfonated poly(ether ether ketone) (SPEEK) through solution casting to prepare SPEEK/SDBS membranes. When no more than 10 wt % SDBS was added, the SDBS was well dissolved into the SPEEK matrix, and the activation energy for the proton transfer in the SPEEK/SDBS membranes was greatly reduced, leading to significant enhancement of the membrane proton conductivity. Compared with the SPEEK control membrane, the SPEEK/SDBS membrane with 10 wt % SDBS showed a 78% increase in proton conductivity, up from 0.051 S cm&minus, 1 to 0.091 S cm&minus, 1, while the water uptake increased from 38% to 62%. Moreover, the SPEEK/SDBS membrane exhibited constant proton conductivity under a long-term water immersion test.