The escalating focus on environmental concerns and the swift advancement of eco-friendly biodegradable batteries raises a pressing demand for enhanced material design in the battery field. The traditional polypropylene (PP) that is monopolistically utilized in the commercial LIBs is hard to recycle. In this work, we prepare a novel water degradable separators via the cross-linking of polyvinyl alcohol (PVA) and dibasic acid (tartaric acid, TA). Through the integration of non-solvent liquid-phase separation, we successfully produced a thermally stable PVA-TA membrane with tunable thickness and a high level of porosity. These specially engineered PVA-TA separators were implemented in LiFePO
In article number 1500716, Liang Zhou, Liqiang Mai, and co-workers report the fabrication of K3V2(PO4)3/C bundled nanowires using a facile organic-acid-assisted method. The organic acid acts as a carbon precursor and as a directing agent, promoting the formation of K3V2(PO4)3/C bundled nanowires. With a highly stable framework, nanoporous structure, and conductive carbon coating, K3V2(PO4)3/C bundled nanowires exhibit fast ion diffusion and excellent electron conduction when used as a cathode material for sodium-ion batteries.
Abstract Extensive effort is being made into cathode materials for sodium‐ion battery to address several fatal issues, which restrict their future application in practical sodium‐ion full cell system, such as their unsatisfactory initial Coulombic efficiency, inherent deficiency of cyclable sodium content, and poor industrial feasibility. A novel air‐stable O3‐type Na[Li 0.05 Mn 0.50 Ni 0.30 Cu 0.10 Mg 0.05 ]O 2 is synthesized by a coprecipitation method suitable for mass production followed by high‐temperature annealing. The microscale secondary particle, consisting of numerous primary nanocrystals, can efficiently facilitate sodium‐ion transport due to the short diffusion distance, and this cathode material also has inherent advantages for practical application because of its superior physical properties. It exhibits a reversible capacity of 172 mA h g −1 at 0.1 C and remarkable capacity retention of 70.4% after 1000 cycles at 20 C. More importantly, it offers good compatibility with pristine hard carbon as anode in the sodium‐ion full cell system, delivering a high energy density of up to 215 W h kg −1 at 0.1 C and good rate performance. Owing to the high industrial feasibility of the synthesis process, good compatibility with pristine hard carbon anode, and excellent electrochemical performance, it can be considered as a promising active material to promote progress toward sodium‐ion battery commercialization.
Abstract Red phosphorus (RP), as a promising anode for potassium‐ion batteries (KIBs), and has attracted extensive attention due to its high theoretical capacity, low redox potential, and abundant natural sources. However, RP shows dramatic capacity decay and rapid structure degradation caused by huge volume expansion and poor electronic conductivity. Here, a volume strain‐relaxation electrode structure is reported, by encapsulating well‐confined amorphous RP in 3D interconnected sulfur, nitrogen co‐doped carbon nanofibers (denoted as RP@S‐N‐CNFs). In situ transmission electron microscopy and the corresponding chemo‐mechanical simulation reveal the excellent structural integrity and robustness of the N, S carbon matrix. As a freestanding anode for KIBs, the RP@S‐N‐CNFs electrode exhibits high reversible capacities (566.7 mAh g −1 after 100 cycles at 0.1 A g −1 ) and extraordinary durability (282 mAh g −1 after 2000 cycles at 2 A g −1 ). The highly reversible one‐electron transfer mechanism with a final discharge product of KP and faster kinetics are demonstrated through in situ characterizations and density functional theory calculations. This work sheds light on the rational design of large‐volume‐vibration type anodes for next‐generation high‐performance KIBs.
Abstract The strategy of inducing interlayer anionic ligands in 2D MoS 1.5 Se 0.5 nanosheets is employed to consolidate the interlayer band gap and optimize the electronic structure for the potassium ion battery. It combines complementary advantages from two kinds of anionic ligands with high conductivity and good affinity with potassium ions. The potassium ion diffusion rate is accelerated as well by an optimized lower energy barrier for ion diffusion pathways, with the formation of highly reversible KMo 3 Se 3 crystal other than K 0.4 MoS 2 /K 2 MoS 4, which encounters a much slower electro/ion diffusion rate upon discharging. These advances deliver enhanced potassium storage properties with excellent cycling stability, with retained specific capacity of 531.6 mAh g −1 at a current density of 200 mA g −1 even after 1000 cycles, and high rate capability with specific capacity of 270.1 mAh g −1 at 5 A g −1 . The insertion and conversion mechanism are also elucidated by a combination of density functional theory computations and in situ synchrotron measurements.
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