Twin Problems of Interfacial Carbonate Formation in Nonaqueous Li–O₂ Batteries

Abstract

We use XPS and isotope labeling coupled with differential electrochemical mass spectrometry (DEMS) to show that small amounts of carbonates formed during discharge and charge of Li-O2 cells in ether electrolytes originate from reaction of Li2O2 (or LiO2) both with the electrolyte and with the C cathode. Reaction with the cathode forms approximately a monolayer of Li2CO3 at the C-Li2O2 interface, while reaction with the electrolyte forms approximately a monolayer of carbonate at the Li2O2-electrolyte interface during charge. A simple electrochemical model suggests that the carbonate at the electrolyte-Li2O2 interface is responsible for the large potential increase during charging (and hence indirectly for the poor rechargeability). A theoretical charge-transport model suggests that the carbonate layer at the C-Li2O2 interface causes a 10-100 fold decrease in the exchange current density. These twin "interfacial carbonate problems" are likely general and will ultimately have to be overcome to produce a highly rechargeable Li-air battery.

Long life rechargeable Li-O2 batteries enabled by enhanced charge transfer in nanocable-like Fe@N-doped carbon nanotube catalyst

“…Some other weak bumps are also observed in XRD spectrum of the recharged cathode possibly due to the formation of a small amount of side reaction products such as Li2CO3, HCO2Li and other Li-based organic compounds during cycling, as suggested by FTIR analysis (Fig. S4) [8,9,44]. FESEM examination reveals the formation of toroidal-aggregates of Li2O2 on the surface of CNTs or carbon black electrode after discharge (Fig.…”

“…Compared with the state-ofthe-art Li-ion batteries, Li-O2 batteries possess dramatically higher energy density (~3500 W h kg −1 ) originated from the reversible reaction of 2Li + O2 ↔ Li2O2 (E0 = 2.96 V vs. Li/Li + ), where the cathode active material (O2) is never exhausted in surrounding environment. However, the application of Li-O2 batteries has still largely hindered by a series of problems such as poor rate capability, low round-trip efficiency, short lifespan and electrolyte instability [8][9][10][11][12][13]. Most of these problems primarily originate from the sluggish kinetics of the oxygen evolution reaction (OER) involved in Li-O2 batteries, which leads to poor reversibility and high polarization [12,[14][15][16][17][18][19].…”

Aqueous and nonaqueous lithium-air batteries enabled by water-stable lithium metal electrodes

“…The gradual voltage increase observed in the experimental curves during charge is possibly related to side reactions resulting in the formation of lithium carbonate layer on the carbon air cathode surface [32].…”

Realizing the Embedded Growth of Large Li2O2 Aggregations by Matching Different Metal Oxides for High‐Capacity and High‐Rate Lithium Oxygen Batteries

“…Also, the peak of Li 2 CO 3 at 870 cm −1 is observed for CP‐MnO 2 and CP‐Co 3 O 4 electrodes. The formation of Li 2 CO 3 is mainly due to the oxidation of carbon during the charge process 59. Thus, this peak may derive from the side reaction related to CP substrate.…”