Analyzing batteries during operation and diagnosing malfunctions at an early stage is essential for increasing efficiency and user safety. Nuclear Magnetic Resonance (NMR) is a rather unique non-invasive and non-destructive technique, as it can simultaneously provide spatial information (imaging) and chemical information (spectroscopy). NMR uses a quantum property of atoms, their spin, to make them " speak " and spy on their environment. Magnetic Resonance Imaging (MRI), in medicine, is one of the many applications of NMR, and the best known of all : the hydrogen atoms contained in water and soft liquids are extremely effective snitches for analyzing tumors, the heart, the brain...
The characterization of batteries in operation by NMR imaging and spectroscopy is more delicate, as these are complex devices, containing solids and conductors that are less amenable to NMR analysis. The strengths and limitations of the technique are discussed, with examples drawn from recent research. The lithium, fluorine, hydrogen, phosphorus and sodium atoms in batteries are questioned about their immediate environment to probe the multiple chemistries taking place at the heart of batteries.
