Suppressing Electrode Crosstalk and Prolonging Cycle Life in High‐Voltage Li Ion Batteries: Pivotal Role of Fluorophosphates in Electrolytes

• DOI: 10.1002/celc.202200469
• Publication Date: 2022-05-09T14:08:26Z
• Authors: Sven Klein; Lukas Haneke; Patrick Harte; Lukas Stolz; Stefan van Wickeren; Kristina Borzutzki; Sascha Nowak; Martin Winter; Tobias Placke; Johannes Kasnatsc...
• Keywords: info:eu-repo/classification/ddc/540; 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology; 7. Clean energy; 3. Good health

Abstract High‐voltage Li ion batteries are compromised by lower cycle life due to enhanced degradation of cathode material, for example LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523). Crucial part is the initiated electrode crosstalk, that transition metal (TM) dissolution from and subsequent deposition on anode, as it forces formation high surface area lithium, capacity losses risk dendrite penetration, finally leading an abrupt end‐of‐life (=rollover failure). Hence, suppression this failure cascade pivotal strategy prolong life. A pragmatic approach was presented: electrolyte manipulation towards formation/presence fluorophosphates, they effectively suppressed crosstalk through TM scavenging. Either, could be intrinsically formed, e. g. elimination ethylene carbonate (EC) solvent (=EC‐free electrolyte), or simply externally added, g . using (good‐soluble) lithium difluorophosphate additive. Their effectiveness demonstrated conventional EC‐based EC‐free electrolytes at limiting conditions (4.5 4.6 V, respectively). In parallel supportive combinations (e. coating), also destructive were highlighted, approaches, which even decrease fluorophosphate content, vinylene additive in electrolytes. Finally, demonstrating value (concentration‐optimized) appropriate benchmark formulations high‐voltage LIBs discussed.