In Situ/ In Operando Electrochemical Studies of Li-ion Batteries

In Situ Electrochemical Studies of Li-Ion Batteries

Detection of the transition metal release from battery material using an electrochemical microprobe.

In recent years Li-ion batteries (LIB) performance greatly improved, because of new developments in the electrode materials. Manganese used in positive LIB electrode materials, like Mn oxides (LMO or spinel-LiₓMn₂O₄), shows excellent electrochemical performance and some fundamental advantages like lower cost and less toxicity in comparison with e.g. LiCoO₂ containing material. We electrochemically deposited a mercury drop onto the tip of a 25 µm Pt disk microelectrodes in order to form Pt/Hg microelectrodes in a glovebox to detect Mn ions.

The combination of this electrochemical probe with square-wave voltammetry makes it possible to measure Mn²⁺ ions in solution with a low detection limit (14 µM). In combination with Scanning Electrochemical Microscopy (SECM), this should provide a new technique for identifying local manganese dissolution from battery electrodes.

Local detection of the li ion diffusion using a Pt/metal ultramicroelectrode Lithium-ion batteries.

Local lithium ion detection in the Lithium Ion Batteries (LIBs) is important as ions Li⁺ ions are exchanged between cathode and anode material via the electrolyte during LIBs charge/ discharge. Therefore, the goal here is to develop a technique, with better reproducibility than current detection techniques, to detect lithium ions transport within the electrolyte filled porous network of the cathode. Scanning electrochemical microscopy (SECM) is used for Li⁺ detection and to monitor its in situ electrochemical behavior. A Ga capped Pt (Pt/Ga) ultramicroelectrode is employed as a probe of SECM to detect lithium ions in a nonaqueous battery electrolyte.

In Operando Electrochemical Studies of Li-Ion Batteries

What if you could see inside a Li-ion battery while you operate it? This is the concept behind “operando” methodologies which allow researchers to experimentally observe fundamental processes that occur within batteries during charge and discharge. One of the most important requirements of modern battery systems for automotive electrification is the ability for fast charge. The speed at which we can charge a battery is often limited by how fast Li-ions can travel from one electrode to the other (solution-phase) or how fast Li can diffuse within the active material (solid-phase).

This research project focuses on using operando X-ray fluorescence and X-ray diffraction to gain valuable information about the solution-phase and solid-phase mass transport in Li-ion batteries. As these X-ray beams must be as small and bright as possible for optimal resolution and rapid data acquisition, a synchrotron radiation source is used. Our team has made multiple trips to the Canadian Light Source (Canada’s only synchrotron) as well as the European Synchrotron Radiation Facility (ESRF) to perform these measurements using a home-made X-ray transparent cell.