Acta Physico-Chimica Sinica ›› 2020, Vol. 36 ›› Issue (4): 1905004.doi: 10.3866/PKU.WHXB201905004

Special Issue: Solid-State Nuclear Magnetic Resonance

Previous Articles     Next Articles

NMR/EPR Investigation of Rechargeable Batteries

Yongchao Shi,Mingxue Tang*()   

  • Received:2019-05-02 Accepted:2019-07-02 Published:2020-03-12
  • Contact: Mingxue Tang E-mail:mingxue.tang@hpstar.ac.cn
  • Supported by:
    the Top-1000 Talents Program of HPSTAR(2301-0219);under grant from Ministry of Finance of China

Abstract:

The fast-growing demand for safe energy storages with high power and energy density drives the continuous improvement of rechargeable Li-ion batteries (LIBs). In situ characterization is a potential way to understand the mechanism (metaphases, diffusion, kinetics, inhomogeneity etc.) of battery under operation conditions. Solid-state nuclear magnetic resonance (SS-NMR) is very sensitive to the local environment of 1H, 6, 7Li, 11B, 13C, 17O, 19F, 23Na, and 31P isotopes, which are widely used in battery materials, regardless of their ordering degree. In addition to providing well-resolved spectra obtained under fast magic angle spinning (MAS), NMR can effectively serve as a non-invasive tool to capture the evolution of electrodes/electrolyte upon charge/discharge electrochemical cycling. Subsequently, in situ NMR and imaging (MRI) have been developed for extending toward temporal and spatial dimensions in working batteries. Complementarily, highly sensitive electron paramagnetic resonance (EPR) and imaging (EPRI) have been employed to track and map the redox of transition metals and oxygen species (O2n) within electrodes. The insights gained from in situ NMR/EPR and their imaging can serve as a guide for the structural design of energy storage materials and the fabrication of batteries with optimized performance. As such, this review summarizes the applications of both NMR and EPR in the field of battery community. In particular, we first introduce the combination of fast magic angle spinning and phase-adjusted sideband separation (pjMATPASS) to obtain highly resolved spectra for extreme broad signal mediated by unpaired electrons, which is usually found in battery materials, as well as isotope-oriented NMR to determine the Li pathway in the composite electrolyte by the aid of 6Li replacing 7Li in their transport pathway. Secondly, we introduce the combination of NMR/MRI measurement while battery under electrochemical cycling by (1) briefly summarizing the advantages and disadvantages of home-made cells (coin cell, bag cell, and cylindrical cell) developed for in situ NMR study; (2) using different isotopes for conducting in situ NMR on batteries: 7Li, 23Na, and 31P spectra; and (3) performing in situ MRI on electrolytes and electrodes with and without chemical shift information (CSI, S-ISIS, and stray-field MRI). Furthermore, in situ EPR determines and quantifies the evolution of active Li microstructure, transition metals, and oxygen species together with in situ EPRI mapping of the concentration of the paramagnetic center within a functioning battery. Finally, we point out the limitations and perspective of in situ NMR and EPR for cycling batteries in real-time. This review will provide illuminating insights on the magnetic technologies in the battery community and pave a way for carrying out NMR/EPR on functional materials.

Key words: Solid-state NMR, Electron paramagnetic resonance, Magnetic imaging, Lithium ion battery, In situ characterization, Structure-function relationship, Dynamic evolution

MSC2000: 

  • O646