Coupling of AFM & Raman spectroscopy with electrochemical techniques for advanced diagnosis of Li-Ion Batteries – CarLIB

Wide-scale implementation of renewable energy will require growth in production of inexpensive, efficient energy storage systems. To address these needs, Li-ion battery systems (LIBs) have been extensively exploited the last two decades. If the actual power density values can be considered quite satisfactory, in particular from automotive industry perspective, i.e. hybrid vehicles (HVs), a drastic increase in energy density is imperative to increase the electric driving range of Battery Electric Vehicles (BEVs) and meet the symbolic target value of 300 miles. New materials with higher Li retention capacity like tin and silicon based anodes as well as high voltage oxide or polyanion-type cathode materials already show great potential to contribute to the forthcoming energy transition. However crucial functional problems/limitations still precipitate the ineluctable degradation of their performance and need to be addressed urgently.

Understanding of the fundamental processes ruling the operation and failure of Li-ion cells has been and is still mostly achieved by cross-comparison of diagnostic techniques run post mortem on the electrodes materials. The proposed project contrast with precedent approach by proposing a cutting edge analytical platform that provides unprecedented diagnostic capabilities applied in operando, i.e. during the battery operation and at multiple scales.

The strategy described herein consists in combining vibrational spectroscopy with local probes and advanced electrochemistry techniques derived from electrochemical impedance techniques (EIS) in a single tool for full diagnostic. By selecting smart couplings, compositional and topographic mapping of battery materials will be implemented either, in operando and at the micron scale (co-localized microRaman and Scanning Probe Microscopies: SPM), or ex situ at the nanoscale (Tip Enhanced Raman Spectroscopy, TERS, enabling nanoRaman). Capturing of Lithium diffusion within the material or at the interface with be also achieved from the macro (EIS and Quartz microbalance) till the micro/nanoscale (EIS and Scanning Electrochemical Microscopy).

By monitoring and correlating the properties of both the active material and of the Solid Electrolyte Interphase (SEI) at various scales, down to 10s of nanometers, we anticipate major breakthrough in the understanding of capacity loss for lithium storage. The following problems/limitations, explaining the capacity fading of selected promising battery materials (tin, silicon, LiNi0.5Mn1.5O4 and LiCoPO4) will be indeed addressed:
1- Instability of the electrode material (chemical, mechanical): loss of active material
2- Side reactions (non-effective passivation of the electrodes): cycleable Lithium irreversibly lost and increase of interfacial resistance
3- Li diffusion and retention limitation: limited charge rate and capabilities

Orientation to the design of the electrode and of the electrolyte will be proposed to circumvent/solve these limitations.

Undoubtedly, the societal impact of this ambitious project will be achieved through in-depth comprehension of the degradation processes enabling more effective R&D on LIBs. Finally, the lower capital investment of local probe techniques run in operando as compared to Nuclear Magnetic Resonance (NMR) or Transmission Electron microscopy (TEM) should make the technology more common place.
ared to Nuclear Magnetic Resonance (NMR) or Transmission Electron microscopy (TEM) should make the technology more common place.