Molecular space linkage of dipentacyclic anhydride additives for long-lifespan Li-metal batteries with Ni-rich cathode

Abstract

The precarious interfacial chemistry between the electrode and electrolyte is the determining step that restricts the long cycle life of Ni-rich-based Li-metal batteries. Here we show that the robust cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) layers can be engineered by tuning the spatial linking structure of dipentacyclic anhydride (DPA) additives. Specifically, an inorganic-rich CEI/SEI layer induced by CBDA (a DPA featuring a quaternary ring spatial linking structure) exhibits superior Li⁺ interfacial kinetics and an ultra-stable cycle performance, outperforming the other systems. As a result, the NCM811ǁLi cells containing CBDA show excellent long-term performances, even under high voltage, high load, and high charge-discharge current density, respectively. The coin-cell using a low-loading cathode exhibits 129 mAh g-¹ discharged capacity for over 200 cycles at a 6 C rate. Moreover, The high-loading cathode retains 80 % capacity after 312 cycles at 1.0 C. Furthermore, the NCM811ǁLi pouch cell demonstrated a capacity retention rate of 99.8 % after 50 cycles. Prolonged stable cycling for 900 cycles (93 % capacity retention) in an NCM811ǁGraphite pouch cell is enabled by CBDA. The DPA-based additives in this work offer a highly promising and feasible route to achieving a long-term and high-capacity lithium battery featuring a Ni-rich cathode.