Regenerated Graphite-Derived Cellular-Inspired Polydopamine@NiO@Graphite toward Robust Lithium Storage.

Although transition metal-based anodes for batteries are preferred owing to their higher energy density, the potential for structural collapse due to volume expansion has hindered their development. Herein, a simulated cellular structured anode composed of uniform nanoparticles and wrapped polydopamine is designed to direct the electronic/ionic diffusion channel and effectively address the volume expansion problem. The controlled-release effects of the polymer between the nano-interface protect the three-dimensional (3D) structures from collapsing during the electrochemical process. The constructed conductive networks along the NiO nanoparticle configurations effectively induce the transfer path and further accelerate the diffusion rate. Furthermore, interstitial filling unlocks the inactive component and triggers the deep delivery of electrons, which boosts battery performance. Therefore, the 3D structured PDA@NiO@G anode prepared from a recycled graphite conductive substrate exhibits excellent specific capacity (500 mAh g-1 at 0.1 A g-1) and significantly improved long-cycle performance (402 mAh g-1 after 500 cycles at 0.5 A g-1). The structure modulation strategy provides meaningful insight into transition metal anodes for the fabrication of high kinetics and prolonged life lithium-ion batteries, as well as the reuse of the spent graphite anode.

Achieving Sustainable and Stable Potassium-Ion Batteries by Leaf-Bioinspired Nanofluidic Flow.

In nature, living systems have evolved integrated structures, matching optimized nanofluidics to adapt to external conditions. In rechargeable batteries, high-capacity electrodes are often plagued by the crucial and universal bottleneck of dissolution and shuttle of active substance into electrolyte, posing obstacles of inevitable capacity degradation. Introducing the concept of intelligent nanofluidics to electrodes, a leaf-bioinspired electrode configuration with hierarchical architecture to tackle this problem is proposed. This integrated structure with fine-tuned surface pores and unobstructed interior porous media, can spatially control the anisotropic nanofluidic flux, in an efficient and self-protectable way: tailoring the outflow across the electrode's surface and free transport in interior, to ensure speedy and stable energy conversion. As proofs of concept, applications of sustainable electrodes rejuvenated from fallen leaf and spent commercial batteries, are designed with leaf-bioinspired architecture. Both KCoS2 and KS battery systems show advanced steady cycling with effectively mitigated shuttle issues in this smart architecture (0.15% and 0.21% capacity decay per cycle), even at high areal mass loading, when compared with open porous structure (0.60% and 0.39%). This work may pave a new way from a biomimetic view to integrated electrode engineering with regulated surface shielding to conquer the universal dissolution-shuttle problems facing high-capacity materials.

P-Doped Ni/NiO Heterostructured Yolk-Shell Nanospheres Encapsulated in Graphite for Enhanced Lithium Storage.

The development of high-efficiency lithium-ion battery electrodes composed of recycled materials is crucial for the commercialization of retired batteries, but it remains a significant barrier. The usage and recycling of spent graphite are encouraged by the huge number of batteries that are going to be dismantled. Here, an anode made of phosphorus-doped Ni/NiO yolk-shell nanospheres embedded on wasted graphite is developed. Electroless deposition and a subsequent heat-treatment procedure are used to make it in a methodical manner. The internal vacuum space of the nanospheres mitigates volume expansion and facilitates Li+ diffusion, whereas the embedded metallic Ni and conductive graphite layer expedite charge transfer. The optimal reusable composite electrode is ecologically benign and has high specific capacities (724 mAh g-1 at 0.1 A g-1 ) as well as outstanding cycle stability (500 cycles). The unusual 3D sandwich-like arrangement with strong spent graphite, the yolk-shell hetero-structure, continuous electron/ion transport routes, and attractive structure stability all contribute to this degree of performance. Such a nanoscale design and engineering strategy not only provides a green recovery method for anode graphite, but also enlightens other nanocomposites to boost their lithium storage performance.