Zhang Yue, Liu Chang, Wu Zhenrui, Manaig Dan, Freschi Donald J, Wang Zhenbo, Liu Jian
School of Engineering, Faculty of Applied Science, University of British Columbia, 3333 University Way, Kelowna, BC V1V 1V7, Canada.
School of Chemistry and Chemical Engineering, Harbin Institute of Technology, No. 92 West-Da Zhi Street, Harbin 150001, China.
ACS Appl Mater Interfaces. 2021 Apr 14;13(14):16345-16354. doi: 10.1021/acsami.1c01155. Epub 2021 Mar 31.
Potassium batteries are an emerging energy storage technology due to the large abundance of potassium, low cost, and potentially high energy density. However, it remains challenging to find suitable electrode materials with high energy density and good cycling stability due to the structural instability and kinetics issues resulting from large size K. Herein, a durable and high-capacity K-Te battery was developed by rational design of a Te/C electrode and electrolyte salt chemistry. A well-confined Te/C cathode structure was prepared by using a commercially available activated carbon as the Te host via a melt-diffusion method. Compared to bulky Te, the confined Te/C electrode exhibited greatly improved cycling stability, specific capacity, and rate capability in K-Te batteries. Moreover, it was found that the electrolyte salts (KPF and KFSI) had significant impacts on the electrochemical performance of K-Te batteries. The Te/C electrode in the KPF-based carbonate electrolyte exhibited higher specific capacity and better rate performance than the Te/C electrode in the KFSI-based one. Mechanism studies revealed that the KPF salt resulted in an organic species-rich solid-electrolyte interphase (SEI) on the Te/C electrode, allowing for fast electron transfer and K-ion diffusion and enhanced K-ion storage performance in K-Te batteries. In contrast, KFSI salt led to the formation of KF-rich SEI layers, which had much higher resistances for electron and K-ion transport and was less effective for the well-confined Te/C electrode. Our work finds that the Te electrode and electrolyte chemistry need to be simultaneously optimized and tailored toward K-ion storage in K-Te batteries. It is expected that the finding reported herein might be inspirable for the future development of K-chalcogen (S/Se/Te) batteries.
钾电池由于钾资源丰富、成本低且具有潜在的高能量密度，是一种新兴的储能技术。然而，由于钾离子尺寸较大导致结构不稳定和动力学问题，寻找具有高能量密度和良好循环稳定性的合适电极材料仍然具有挑战性。在此，通过合理设计碲/碳电极和电解质盐化学，开发了一种耐用且高容量的钾-碲电池。通过熔融扩散法，使用市售活性炭作为碲的主体，制备了一种受限良好的碲/碳阴极结构。与块状碲相比，受限的碲/碳电极在钾-碲电池中表现出大大提高的循环稳定性、比容量和倍率性能。此外，发现电解质盐（KPF和KFSI）对钾-碲电池的电化学性能有显著影响。基于KPF的碳酸盐电解质中的碲/碳电极比基于KFSI的电解质中的碲/碳电极表现出更高的比容量和更好的倍率性能。机理研究表明，KPF盐在碲/碳电极上形成了富含有机物种的固体电解质界面（SEI），使得电子转移和钾离子扩散加快，并增强了钾-碲电池中的钾离子存储性能。相比之下，KFSI盐导致形成富含KF的SEI层，其对电子和钾离子传输的电阻要高得多，并且对受限良好的碲/碳电极效果较差。我们的工作发现，在钾-碲电池中，碲电极和电解质化学需要同时针对钾离子存储进行优化和调整。预计本文报道的发现可能会为钾族元素（硫/硒/碲）电池的未来发展提供启发。
