Dynamics of transition metal dissolution and cross-contamination in operating Lithium-ion batteries

Chemical crosstalk in functioning batteries, which describes the shuttling of electrolyte soluble reactive species through the separator and the disruption of the electrode operation is a major concern, which impacts the development of new electrode generation for lithium or sodium ion/metal batteries and therefore needs to be addressed urgently. The accurate depiction of the origin, the dynamics and deleterious effects of crosstalk process upon cycling of the battery, precondition to possible remediation, requires new operando diagnostic solutions. In this work, a powerful crosstalk sensing technique based on the electrochemical trapping of redox shuttles is introduced and applied to the high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode material. Leaching and transport of transition metal species from the LNMO composite electrode and of electrolyte oxidation products could be evidenced, quantified and tracked upon cycling of the LNMO//Li system, unraveling the critical impact of the electrolyte composition and its resistance to oxidation. • Simple operando crosstalk sensor with minimal electrochemical “footprint”. • Real-time tracking and trapping of redox shuttles by electrodeposition. • Quantification of LNMO dissolution at any operating voltage. • Larger dissolution at high voltages and in less oxidation resistant electrolytes.