Ulvestad Asbjørn, Skare Marte O, Foss Carl Erik, Krogsæter Henrik, Reichstein Jakob F, Preston Thomas J, Mæhlen Jan Petter, Andersen Hanne F, Koposov Alexey Y
Department of Battery Technology, Institute for Energy Technology, Instituttveien 18, NO-2027 Kjeller, Norway.
Department of Materials Science and Engineering, Norwegian University of Science and Technology, Alfred Getz vei 2, NO-7491 Trondheim, Norway.
ACS Nano. 2021 Oct 26;15(10):16777-16787. doi: 10.1021/acsnano.1c06927. Epub 2021 Sep 27.
In modern Li-based batteries, alloying anode materials have the potential to drastically improve the volumetric and specific energy storage capacity. For the past decade silicon has been viewed as a "Holy Grail" among these materials; however, severe stability issues limit its potential. Herein, we present amorphous substoichiometric silicon nitride (SiN) as a convertible anode material, which allows overcoming the stability challenges associated with common alloying materials. Such material can be synthesized in a form of nanoparticles with seamlessly tunable chemical composition and particle size and, therefore, be used for the preparation of anodes for Li-based batteries directly through conventional slurry processing. Such SiN materials were found to be capable of delivering high capacity that is controlled by the initial chemical composition of the nanoparticles. They exhibit an exceptional cycling stability, largely maintaining structural integrity of the nanoparticles and the complete electrodes, thus delivering stable electrochemical performance over the course of 1000 charge/discharge cycles. Such stability is achieved through the conversion reaction, which was herein unambiguously confirmed by pair distribution function analysis of cycled SiN nanoparticles revealing that active silicon domains and a stabilizing LiSiN phase are formed during the initial lithiation.
在现代锂基电池中，合金化负极材料有潜力大幅提高体积和比能量存储容量。在过去十年里，硅在这些材料中被视为“圣杯”；然而，严重的稳定性问题限制了其潜力。在此，我们展示了非晶亚化学计量氮化硅（SiN）作为一种可转换负极材料，它能够克服与常见合金化材料相关的稳定性挑战。这种材料可以以纳米颗粒的形式合成，其化学成分和粒径可无缝调节，因此可直接通过传统的浆料工艺用于制备锂基电池的负极。发现这种SiN材料能够提供由纳米颗粒的初始化学成分控制的高容量。它们表现出卓越的循环稳定性，在很大程度上保持了纳米颗粒和完整电极的结构完整性，从而在1000次充/放电循环过程中提供稳定的电化学性能。这种稳定性是通过转换反应实现的，本文通过对循环后的SiN纳米颗粒的对分布函数分析明确证实，在初始锂化过程中形成了活性硅域和稳定的LiSiN相。
