Ultra-stable K metal anode enabled by oxygen-rich carbon cloth
- PDF / 2,010,171 Bytes
- 5 Pages / 612 x 808 pts Page_size
- 29 Downloads / 147 Views
School of Metallurgy and Environment, Central South University, Changsha 410083, China Contemporary Amperex Technology Co., Ltd., Ningde 352100, China
© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 14 May 2020 / Revised: 2 July 2020 / Accepted: 10 July 2020
ABSTRACT The K metal batteries are emerged as promising alternatives beyond commercialized Li-ion batteries. However, suppressing uncontrolled dendrite is crucial to the accomplishment of K metal batteries. Herein, an oxygen-rich treated carbon cloth (TCC) has been designed as the K plating host to guide K homogeneous nucleation and suppress the dendrite growth. Both density function theory calculations and experimental results demonstrate that abundant oxygen functional groups as K-philic sites on TCC can guide K nucleation and deposition homogeneously. As a result, the TCC electrode exhibits an ultra-long-life over 800 cycles at high current density of 3.0 mA·cm–2 for 3.0 mA·h·cm–2. Furthermore, the symmetrical cells can run stably for 2,000 h with low over-potential less than 20 mV at 1.0 mA·cm–2 for 1.0 mA·h·cm–2. Even at a higher current of 5.0 mA·cm–2, the TCC electrode can still stably cycle for 1,400 h.
KEYWORDS K metal anode, dendrite, oxygen-rich treated carbon cloth, K-philic sites, ultra-long-life
1
Introduction
For the restrain of limited and unevenly distributed Li in the earth’s crust (0.0017 wt.%), Li batteries no longer meet the growing demand for the next-generation storage system of high energy density [1]. As a cheaper and more abundant alternative to Li, K is more than one thousand times of Li geographically [2]. Moreover, the electrochemical potential of K/K+ in nonaqueous electrolytes with high specific capacity (≈ 687 mA·h·g−1) is even lower than that of Li/Li+ [3, 4]. Additionally, K can match with sulfur or oxygen to compose high energy density K–S or K–O2 batteries [5, 6]. However, directly using K as anode in cells remains a challenge. The unstable solid electrolyte interphase (SEI) on K metal surface can continuously break and reconstruct during cycling, which depletes the limited K [7, 8]. Furthermore, the structural and geometric inhomogeneity of metal current collectors like Cu in their production process leads to an uneven nucleation and deposition of K. After repeated cycling for many times, the cell will get a poor Coulombic efficiency and premature cell failure. Moreover, the weak connection between matrix and deposited K will induce K easily shed from the matrix [9]. The shedding K is fast wrapped by the new SEI and generates isolated “dead K” with electrochemical inactivity, which further expends the limited K. Both of them will lead to the decrease of Coulombic efficiency and poor cycling performance [4]. In addition, nonuniformty of ion flux on SEI will induce an uneven deposition and growth, thus promoting the formation of dendrite [10–12]. And the K dendrites may pierce the separator and finally cause internal short circuit. As a result, the issues of low Coulombi
Data Loading...
