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.
Tailoring inorganic components of cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) is critical to improving the cycling performance of lithium metal batteries. However, it is challenging due to complicated electrolyte reactions on cathode/anode surfaces. Herein, the species and inorganic component content of the CEI/SEI is enriched with an objectively gradient distribution through employing pentafluorophenyl 4-nitrobenzenesulfonate (PFBNBS) as electrolyte additive guided by engineering bond order with functional groups. In addition, a catalytic effect of LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NCM622) cathode is proposed on the decomposition of PFBNBS. PFBNBS with lower highest occupied molecular orbital can be preferentially oxidized on the NCM622 surface with the help of the catalytic effect to induce an inorganic-rich CEI for superior electrochemical performance at high voltage. Moreover, PFBNBS can be reduced on the Li surface due to its lower lowest unoccupied molecular orbital , increasing inorganic moieties in SEI for inhibiting Li dendrite generation. Thus, 4.5 V Li||NCM622 batteries with such electrolyte can retain 70.4% of initial capacity after 500 cycles at 0.2 C, which is attributed to the protective effect of the excellent CEI on NCM622 and the inhibitory effect of its derived CEI/SEI on continuous electrolyte decomposition.
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