High energy density Ni-rich layered oxide cathodes LiNi0.83Co0.12Mn0.05-xAlxO2 (x=0, 0.025, 0.05; NMC, NMCA, and NCA, respectively) are fabricated in two different microstructural forms: (i) nanoparticles (NP) and (ii) nanofibers (NF), to evaluate the morphology and compositional effect on the electrochemical properties using same precursors, with the latter fabricated by electrospinning process. Although all the cathodes exhibit a similar crystal structure as confirmed by X-ray diffraction and Raman spectroscopy, contrasting difference is observed in their electrochemical properties. XRD and XPS analyses indicate a higher amount of cationic disorder for the NP cathodes compared to their NF counterparts. Nanofibrous Ni-rich layered oxide cathodes exhibit higher discharge capacities at all C-rates in comparison to NP cathodes. When cycled at 1C-rate for 100 cycles, capacity retention of 81% is observed for NCA-NF, which is superior to all cathodes. Voltage decay as a function of the charge-discharge cycle is found to be low (0.2 mV/cycle) for nanofibrous cathodes compared to 1.5 mV/cycle for NP cathodes. The good rate capability and cyclic stability of nanofibrous Ni-rich layered oxide cathodes are attributed to a shorter pathway of Li+ diffusion and a large proportion of the active surface area.

Once batteries reach their end-of-life (EoL), they are expected to be collected, dismantled, and shredded into black mass (BM) which includes wealth amounts of critical metals. BM can be regarded as a kind of urban mines, where recyclers extract critical metals and reintroduce them into new battery manufacturing. Focusing on the BM, this article discussed the necessity of BM recovery and current recycling situations. Although the benefits of recycling are commonly agreed upon, there remain still many challenges and issues to overcome. The BM market is still in its infancy, relevant regulatory frameworks need to be updated with the widespread use and advancement of lithium-ion batteries (LIBs). Current BM-producing and processing technologies still have room for large improvements in terms of economic feasibility and sustainability that in the end requires efforts from both researchers and industrial stakeholders with growing interests and patient engagements.

The aqueous metal-H2O2 batteries have been paying rapidly increasing attention due to their large theoretical energy densities, high power density, and multiple applications (air, land, and sea), especially in low-content oxygen or nonoxygen conditions in which metal-air cells are out of work. However, the requirements of metal-H2O2 batteries are different due to the order of metal activities (Mg>Al>Zn) as well as metal-air cells. Aqueous metal-H2O2 batteries mainly include Al-H2O2, Mg-H2O2, and Zn-H2O2 batteries with respective scientific problems, including battery structures, single/dual-electrolyte systems, electrocatalysts for oxygen reduction/evolution reactions and H2O2 reduction/production/decomposition, and the designability of anode to inhibit self-corrosion. In this review, we summarized battery architectures, possible mechanisms, and recent progress in metal-H2O2 batteries including Al-H2O2, Mg-H2O2, and Zn-H2O2 batteries. Several perspectives are also provided for these research fields, which may be focused on in the future.

Bi2O3 (BT) is considered a fascinating anode material for asymmetric supercapacitors (ASCs) due to its high theoretical capacity, but the low conductivity limits further applications. With this in mind, cerium-doped Bi2O3 (Ce−BT) nanoflower spheres were synthesized by a facile and rapid microwave-assisted solvothermal method for ASCs anode materials. It is found that the morphology of BT could be controlled by Ce doping from stacked nanosheets to well-dispersed nanoflowers spheres and producing abundant amorphous regions, thus expediting the ion transport rate. Consequently, When the added Bi to Ce molar ratio is 40:1 (Ce-BT-40), it exhibited a specific capacitance of 721 F g−1 at 0.5 A g−1. Additionally, when fabricating ASCs with as-prepared Ce−BT−40 and CeNiCo-LDH, an energy density of 59.1 Wh kg−1 is provided at a power density of 652 W kg−1. This work not only reveals the mechanism of the effect of Ce doping on the electrochemical properties of BTs but also proposes a rapid synthesis method of Ce−BTs by microwave-assisted solvent method, which provides new insights for building advanced ASCs with high energy density and low cost.