Low Redox Potential InN Nanowires as High-Energy-Density Anode for Lithium-Ion Batteries

Abstract

Lithium-ion batteries (LIBs) have become the most predominant energy sources for various digital products and electric vehicles due to the rechargeable, high capacity, and no memory effect characteristics. Charging to 80% of the full capacity time is commonly required to be less than 30 minutes in the future as technological development. Thus, it is essential to improve the dynamics of the active material [1]. The current approach to increasing the energy density of LIBs is to increase the electrode loading mass. This has the effect of greatly increasing the thickness of the electrodes, making it difficult for Li-ions to quickly pass through the electrode. Graphite anode is the most widely used anode material due to its low cost, easy preparation, and applicable working voltage below 0.3 V (vs Li/Li+). However, its low capacity and disordered staging behavior at large currents limit the fast charging performance. Moreover, due to the low density of graphite, when designed as a high-energy density cell, its thickness increases considerably, significantly reducing the Li-ions diffusion. Therefore, new active materials with high capacity and fast Li-ions diffusion should be developed to achieve high-energy-density cells.As a well-known semiconductor, Indium Nitride (InN) has been widely used for various applications such as high-frequency terahertz and solar energy devices. When it is denoted as an anode for LIBs, the InN can deliver a theory specific capacity over 1200 mAh g-1, which is nearly four times of the conventional graphite anodes (~372 mAh g-1). Meanwhile, it shows a relatively low redox potential (below 0.7 V vs. Li+/Li), affording a wide voltage window for a full cell. Remarkably, the InN is a narrow band (0.69 eV) semiconductor showing good electron transfer properties. Thus, the InN could be considered as one of the most promising anode for the next-generation HED-LIBs. However, the inherent volume change of InN particles during the conversion and alloying/dealloying process with Li+ maybe lead to many adverse effects, including pulverization of InN particles electrode, tearing solid electrolyte interphase (SEI). The fact finally worsens the Li-storage performance, greatly hindering the commercial application of InN anode. In addition, the sluggish ion diffusion of InN particles also limits the rate capability. To address the issues, approaches like constructing micro/nano composite structures, which have been broadly explored to alleviate the volume expansion and improve ion diffusion [2]. Among these micro/nanostructures, the 1D nanostructure shows superior physicochemical properties in favor of improving Li-storage performance. Firstly, the One-dimensional (1D) nanostructures can accommodate the strain of Li-ions delidiation/lidiation along specified directions. Secondly, the gap of the 1D nanostructure is just enough to provide a buffer during the charge/discharge process. Thirdly, the 1D nanostructure is beneficial to the Li-ions diffusion leading to good rate performance [3]. Moreover, the 1D structure has the advantage of self-forming film, which greatly reduces the weight of the electrode. It is worth noting that the large ratio aspect of 1D nanostructure can lower the ion diffusion paths accelerating the rate performance.Herein, we elaborately constructed the single-crystal InN nanowires on carbon fibers (InN/Au-CFs). Firstly, the CFs are decorated with Au nanoparticles by a magnetron sputtering method, which can afford many stable growth sites for InN nanowires. And then, the InN nanowires in situ grown on the Au nanoparticle surface by chemical vapor deposition successfully improved the adhesive force active material and substrate. The structural properties and Li-storage performance of InN/Au-CFs are systematically studied. In addition, the density of state and adatom adsorption of InN nanowires are calculated by density functional theory. The ion diffusion, reactivity, and electrode stability are successfully enhanced based on the results. We also built two-terminal electrodes to decelerate the metal electrode fatigue at large rate for a full cell. Particularly, the as-prepared InN/Au-CFs anode can deliver the capacities of 624.2 mAh g-1 at 0.1 A g-1 after 500 cycles and 416 mAh g-1 at 30 A g-1 for the rate assessment, respectively. Our work suggests that the embellishment one dimentional InN nanowire and two-terminal electrodes are a successful strategy for HED-LIBs contributing excellent long cycling performance and large rate capability.[1] J. Kim et al, Nat. Rev. Mater. 8(1) (2023) 54-70.[2] A. M. Bates, et al, Joule 6(4) (2022) 742-755.[3] L. Xing et al, Nano Energy 79 (2021) 105384. Figure 1