Ultra-Low-Dose Pre-Metallation Strategy Served for Commercial Metal-Ion Capacitors

Zirui Song; Guiyu Zhang; Xinglan Deng; Kangyu Zou; Xuhuan Xiao; Roya Momen; Abouzar Massoudi; Wentao Deng; Jiugang Hu; Hongshuai Hou; Guoqiang Zou; Xiaobo Ji

doi:10.1007/s40820-022-00792-x

Ultra-Low-Dose Pre-Metallation Strategy Served for Commercial Metal-Ion Capacitors

Nanomicro Lett. 2022 Jan 29;14(1):53. doi: 10.1007/s40820-022-00792-x.

Authors

Zirui Song¹, Guiyu Zhang¹, Xinglan Deng¹, Kangyu Zou¹, Xuhuan Xiao¹, Roya Momen¹, Abouzar Massoudi², Wentao Deng¹, Jiugang Hu¹, Hongshuai Hou¹, Guoqiang Zou³, Xiaobo Ji^{1

4}

Affiliations

¹ College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, People's Republic of China.
² Department of Semiconductors Materials and Energy Research Center, P.O. Box 14155/4777, Tehran, Iran.
³ College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, People's Republic of China. gq-zou@csu.edu.cn.
⁴ College of Material Science and Engineering, Zhengzhou University, Zhengzhou, 450001, People's Republic of China.

Abstract

Interfacial bonding strategy has been successfully applied to address the high overpotential issue of sacrificial additives, which reduced the decompositon potential of Na₂C₂O₄ from 4.50 to 3.95 V. Ultra-low-dose technique assisted commercial sodium ion capacitor (AC//HC) could deliver a remarkable energy density of 118.2 Wh kg^-1 as well as excellent cycle stability. In-depth decomposition mechanism of sacrificial compound and the relative influence after pre-metallation were revealed by advanced in situ and ex situ characterization approaches. Sacrificial pre-metallation strategy could compensate for the irreversible consumption of metal ions and reduce the potential of anode, thereby elevating the cycle performance as well as open-circuit voltage for full metal ion capacitors (MICs). However, suffered from massive-dosage abuse, exorbitant decomposition potential, and side effects of decomposition residue, the wide application of sacrificial approach was restricted. Herein, assisted with density functional theory calculations, strongly coupled interface (M-O-C, M = Li/Na/K) and electron donating group have been put forward to regulate the band gap and highest occupied molecular orbital level of metal oxalate (M₂C₂O₄), reducing polarization phenomenon and Gibbs free energy required for decomposition, which eventually decrease the practical decomposition potential from 4.50 to 3.95 V. Remarkably, full sodium ion capacitors constituted of commercial materials (activated carbon//hard carbon) could deliver a prominent energy density of 118.2 Wh kg^-1 as well as excellent cycle stability under an ultra-low dosage pre-sodiation reagent of 15-30 wt% (far less than currently 100 wt%). Noteworthily, decomposition mechanism of sacrificial compound and the relative influence on the system of MICs after pre-metallation were initially revealed by in situ differential electrochemical mass spectrometry, offering in-depth insights for comprehending the function of cathode additives. In addition, this breakthrough has been successfully utilized in high performance lithium/potassium ion capacitors with Li₂C₂O₄/K₂C₂O₄ as pre-metallation reagent, which will convincingly promote the commercialization of MICs.

Keywords: Coupled interface; Decomposition potential; Metal oxalate; Pre-metallation.