Simple Designed Micro-Nano Si-Graphite Hybrids for Lithium Storage.

Up to now, the silicon-graphite anode materials with commercial prospect for lithium batteries (LIBs) still face three dilemmas of the huge volume effect, the poor interface compatibility, and the high resistance. To address the above challenges, micro-nano structured composites of graphite coating by ZnO-incorporated and carbon-coated silicon (marked as Gr@ZnO-Si-C) are reasonably synthesized via an efficient and convenient method of liquid phase self-assembly synthesis combined with annealing treatment. The designed composites of Gr@ZnO-Si-C deliver excellent lithium battery performance with good rate performance and stable long-cycling life of 1000 cycles with reversible capacities of 1150 and 780 mAh g-1 tested at 600 and 1200 mA g-1 , respectively. The obtained results reveal that the incorporated ZnO effectively improve the interface compatibility between electrolyte and active materials, and boost the formation of compact and stable surface solid electrolyte interphase layer for electrodes. Furthermore, the pyrolytic carbon layer formed from polyacrylamide can directly improve electrical conductivity, decrease polarization, and thus promote their electrochemical performance. Finally, based on the scalable preparation of Gr@ZnO-Si-C composites, the pouch full cells of Gr@ZnO-Si-C||NCM523 are assembled and used to evaluate the commercial prospects of Si-graphite composites, offering highly useful information for researchers working in the battery industry.

Novel Binder with Cross-Linking Reconfiguration Functionality for Silicon Anodes of Lithium-Ion Batteries.

Silicon is expected to be used as a high theoretical capacity anode material in lithium-ion batteries with high energy densities. However, the huge volume change incurred when silicon de-embeds lithium ions, leading to destruction of the electrode structure and a rapid reduction in battery capacity. Although binders play a key role in maintaining the stability of the electrode structure, commonly used binders cannot withstand the large volume expansion of the silicon. To alleviate this problem, we propose a PGC cross-linking reconfiguration binder based on poly(acrylic acid) (PAA), gelatin (GN), and ß-cyclodextrin (ß-CD). Within PGC, PAA supports the main chain and provides a large number of carboxyl groups (-COOH), GN provides rich carboxyl and amide groups that can form a cross-linking network with PAA, and ß-CD offers rich hydroxyl groups and a cone-shaped hollow ring structure that can alleviate stress accumulation in the polymer chain by forming a new dynamic cross-linking coordination conformation during stretching. In the half cell, the silicon negative prepared by the PGC binder exhibited a high specific capacity and capacity maintenance ratio, and the specific capacity of the silicon negative electrode prepared by the PGC binder is still 1809 mAh g-1 and the capacity maintenance ratio is 73.76% following 200 cycles at 2 A g-1 current density, indicating that PGC sufficiently maintains the silicon negative structure during the battery cycle. The PGC binder has a simple preparation method and good capacity retention ability, making it a potential reference for the further development of silicon negative electrodes.