Understanding the Reaction Chemistry during Charging in Aprotic Lithium–Oxygen Batteries: Existing Problems and Solutions

Abstract

The aprotic lithium-oxygen (Li-O 2 ) battery has excited huge interest due to its having the highest theoretical energy density among the different types of rechargeable battery. The facile achievement of a practical Li-O 2 battery has been proven unrealistic, however. The most significant barrier to progress is the limited understanding of the reaction processes occurring in the battery, especially during the charging process on the positive electrode. Thus, understanding the charging mechanism is of crucial importance to enhance the Li-O 2 battery performance and lifetime. Here, recent progress in understanding the electrochemistry and chemistry related to charging in Li-O 2 batteries is reviewed along with the strategies to address the issues that exist in the charging process at the present stage. The properties of Li 2 O 2 and the mechanisms of Li 2 O 2 oxidation to O 2 on charge are discussed comprehensively, as are the accompanied parasitic chemistries, which are considered as the underlying issues hindering the reversibility of Li-O 2 batteries. Based on the detailed discussion of the charging mechanism, innovative strategies for addressing the issues for the charging process are discussed in detail. This review has profound implications for both a better understanding of charging chemistry and the development of reliable rechargeable Li-O 2 batteries in the future.

Cauliflower‐Like Hierarchical Porous Nickel/Nickel Ferrite/Carbon Composite as Superior Bifunctional Catalyst for Lithium‐Air Battery

“…In the bulk discharge product Li 2 O 2 leads to the sluggish kinetics during OER and results in high charge overpotential, owing to the decomposition of non‐aqueous electrolyte. Thus, the development of a better OER catalyst is indespensable to decompose the Li 2 O 2 at lower overpotential.…”

“…Hence, porous structured oxygen electrode catalyst with large surface area is preferred which can also accommodate the volume change occuring during the formation of discharge products (Li 2 O and Li 2 O 2 ). Shu et al., reported the list of catalysts such as Pt, Ni, Au, Mo 2 C, and LiCo 2 O 4 towards decomposition of the side products in the Li–O 2 battery.…”

Critical Advances in Ambient Air Operation of Nonaqueous Rechargeable Li–Air Batteries

“…[88] Li anode and its discharge species, e.g. LiO2, Li2O2, or LiOH, gradually react with CO2 to form Li2CO3, according to Equations (4)(5)(6). Li2CO3 is a wide band-gap insulator and electrochemically irreversible, which will result in a high oxidation potential during charging (> 4 V).…”

“…Therefore, it is imperative to develop new alternatives that extend beyond Li-ion technology to meet the energy storage needs of future generations. [2][3][4][5][6][7] Among all the battery systems going beyond Li-ion, the non-aqueous Li-air battery has attracted enormous research attention. [8][9][10][11][12][13][14] It could deliver theoretical specific energy that is almost 3-4 times that of the most advanced Li-ion batteries.…”

The effect of CO2 contamination in rechargeable non-aqueous sodium–air batteries

“…Though metal−air batteries certainly show promise, there are several scientific and technical challenges which must be addressed before commercialization. These include low accessible capacity 8 , poor conductivity and rechargeability 7,[9][10][11][12][13] , instability of electrodes [14][15][16][17] , electrolytes 18 and salts 19,20 and high sensitivity to trace gases. [21][22][23][24][25][26] Despite its lower capacity and potential than the Li−O2 battery, the Na−O2 battery has gained much attention due to its low discharge/charge overpotentials (~100 mV) at relatively high current densities (0.2 mA/cm 2 ) and high electrical energy efficiency (90%).…”