Artificial CEI construction via fluorosulfonates additive in high voltage lithium batteries to inhibit the transition metals dissolution

Increasing the voltage of lithium batteries represents the most direct and effective strategy for enhancing battery capacity. However, excessively high charging voltages can result in the degradation of battery interfacial contacts and the dissolution of transition metals in the cathode, thereby limiting the cycling performance of the battery. This paper employs a fluorosulfonic acid salt electrolyte as a sacrificial agent to in situ construct a stable CEI (Cathode Electrolyte Interface) and SEI (Solid Electrolyte Interface). The resulting membrane is characterized by a uniform distribution of LiF and LiSO x , which exhibit high lithium-ion conductivity and mitigate dissolution of active materials under high voltage. This membrane effectively restricts further electrolyte consumption, allowing the remaining electrolyte to wet the interface and reduce interfacial impedance adequately. Moreover, the CEI can suppress the dissolution of transition metals from the cathode and prevent them from shuttling to the anode side. When implemented in lithium batteries, the use of the sacrificial agent enables the NCM523/Li battery (with an initial discharge capacity of 105 mAh/g) to achieve a high capacity retention of 85.7 % after 800 cycles at a 1 C rate and 30 °C.