In this study, we fabricated a porous calcium alginate/graphene oxide composite aerogel by using polystyrene colloidal particles as sacrificial template and graphene oxide as a reinforcing filler. Owing to the excellent metal chelation ability of calcium alginate and controlled nanosized pore structure, the as-prepared calcium alginate/graphene oxide composite aerogel (mp-CA/GO) can reach the adsorption equilibrium in 40 min, and the maximum adsorption capacity for Pb2+, Cu2+ and Cd2+ is 368.2, 98.1 and 183.6 mg/g, respectively. This is higher than most of the reported heavy metal ion sorbents. Moreover, the mp-CA/GO can be regenerated through simple acid-washing and be used repeatedly with little loss in performance. The adsorption mechanism analysis indicates that the mp-CA/GO adsorb the heavy metal ions mainly through the ion exchange and chemical coordination effects.
Graphene
has been wildly used as a host to suppress dendrite growth
to stabilize the lithium metal anode. However, the high overpotential
of lithium deposition on pure graphene has to be lowered by doping
or employing precious metals. Additionally, the soft nature of graphene
rendered itself to aggregate, consequently squeezing room for lithium
accommodation. Herein, a tough graphene framework composed of 3D periodic
hollow spheres was reported as a free-standing host to stabilize lithium
metal anodes. The prepared 3D periodic hollow structure not merely
reinforces the framework to maintain hollow structure under pressure
caused by assembling battery, but also lowers the overpotential without
the help of dopant or precious metals. It is worthy to note that high
efficiency of ion diffusion, thanks to the channels interconnecting
hollow spheres by holes on the walls, benefits both suppression of
lithium dendrite and rate capability. The properties of low density
and high mechanical strength make graphene frameworks electrode a
promising lightweight Li host material, which reveals a new avenue
for designing high-energy density electrode materials.
Carbon materials with a high specific surface area are usually preferred to construct the air cathode of lithium–air batteries due to their abundant sites for oxygen reduction and discharge product growth. However, the high surface area also amplifies electrolyte degradation during charging, which would become the threshold of cyclability after addressing the issue of electrode passivation and pore clogging, but is usually overlooked in relevant research. Herein, it is proven that the critical influence of cathode surface area on electrolyte consumption by adopting carbon–ceramic composites to reduce the surface area of the air cathode. After screening several potential ceramic materials, an optimal composite of Ketjenblack (KB) and La0.7Sr0.3MnO3 (LSM) delivered a discharge capacity that was even higher than that of pure KB. This composite effectively mitigated the parasitic reaction current by 45 % if polarized at 4.4 V versus Li+/Li. Correspondingly, this composite prolonged the cycle life of the cell by 156 %. The results demonstrate that electrolyte consumption during charging is one of the critical boundary conditions to restrain the cyclic stability of lithium–air batteries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.