Water-Stable Lithium Anode with the Three-Layer Construction for Aqueous Lithium–Air Secondary Batteries

Abstract

A water-stable multilayer Li-metal electrode consisting of a lithium metal, a PEO 18 LiN͑SO 2 CF 3 ͒ 2 -BaTiO 3 composite polymer, and a lithium-conducting glass ceramic Li 1.35 Ti 1.75 Al 0.25 P 0.9 Si 0.1 O 12 ͑LTAP͒ was proposed as the lithium anode for aqueous lithium-air secondary batteries. The addition of finely dispersed nanosize BaTiO 3 in the polymer electrolyte greatly reduced the interfacial resistance between the Li anode and the polymer electrolyte. A Li/PEO 18 LiN͑SO 2 CF 3 ͒ 2 -10 wt % BaTiO 3 /LTAP electrode showed a total resistance of 175 ⍀ cm 2 in a 1 M aqueous LiCl solution at 60°C, with no change in the electrode resistance over a month. The Li/PEO 18 LiN͑SO 2 CF 3 ͒ 2 -10 wt % BaTiO 3 /LTAP/aqueous 1 M LiCl/Pt air cell had a stable opencircuit voltage of 3.80 V, which was equivalent to that calculated from the cell reaction of 2Li + 1/2O 2 + H 2 O = 2LiOH. The cell exhibited a stable and reversible discharge/charge performance of 0.5 mA cm −2 at 60°C, suggesting excellent reversibility of the lithium oxidation reduction reaction for the Li/PEO 18 LiN͑SO 2 CF 3 ͒ 2 -10 wt % BaTiO 3 /LTAP electrode. Metal-air batteries usually consist of a metal anode electrochemically coupled to oxygen, which is obtained from the environment through an air cathode. This type of battery is unique because oxygen is not stored in the cathode and is essentially an unlimited reactant source. Thus the capacity of the battery is theoretically limited only by the metal anode.1 Of all the metal-air batteries, the lithium-air battery has the highest theoretical specific energy of 11,140 Wh kg −1 with a calculated open-circuit voltage ͑OCV͒ of 2.91 V, based on the cell reaction 4Li + O 2 = 2Li 2 O, in a nonaqueous electrolyte.2,3 This specific energy is eight times higher than that of Zn-air and is comparable with that of a gasoline-air system. It is, therefore, expected that lithium-air batteries will have a potential as a power source, with high energy density, for use in advanced electric vehicles.4 A rechargeable lithium-air battery, using a polyacrylonitrile-based plasticized polymer electrolyte, was reported in 1996 by Abraham and Jiang.2 This cell showed a discharge capacity of 1600 mAh g −1 , and the specific energy density, including the weight of the electrode and the electrolyte, was estimated to be 250-350 Wh kg −1 . Read et al. 5,6 also observed a high discharge capacity of 2120 mAh g −1 during their detailed study of the electrolyte and air cathode formulation of a lithium/oxygen organic electrolyte cell. Ogasawara et al. 7 presented more attractive results in a rechargeable lithium-oxygen cell, with an organic electrolyte and a MnO 2 catalyst for Li 2 O 2 reduction. A high charge and discharge capacity of 600 mAh g −1 was achieved after 50 cycles, compared with a reversible capacity of 150 mAh g −1 for the cathode materials in conventional lithium-ion batteries. Recently, the authors showed improved discharge capacity, with better cyclability, using nanowire ␣-MnO 2 catalysts.8 This high cathode capacit...

Metal–Air Batteries with High Energy Density: Li–Air versus Zn–Air

“…[ 20 , 21 ] Various ionic conducting glass-ceramic protective double layers have been introduced to improve the charge -ransfer reaction of Li ions between Li metal and aqueous electrolytes. [22][23][24][25] The Imanishi group reported that Li 1 + x + y Al x Ti 2-x Si y P 3-y O 12 was stable in water, but is reactive with Li metal. However, a glass-ceramic Li 3-x PO 4-y N y (LiPON) and a lithium-conducting polymer electrolyte (PEO 18 LiTFSI) inhibited the direct reaction of Li and LATP.…”

Development of a 4.2 V aqueous hybrid electrochemical capacitor based on MnO2 positive and protected Li negative electrodes

“…[12][13][14] A PEO film (ca. 300 µm thickness) containing LiTFSI and BaTiO3 was placed between a LTAP glass ceramic (10 mm × 10 mm × 0.15 mm) and lithium foil (5 mm × 5 mm × 0.2 mm).…”

“…[11] The protected Li electrode, which has been developed for use as a negative electrode in Li-Air rechargeable battery, is fabricated by sealing Li metal and a Li-ion conducting solid electrolyte with an aluminum package. [12][13][14] The AdHiCap combines the battery-like redox reaction at the Li negative electrode and capacitive charge storage at the positive electrode, similar to a lithium ion capacitor (LIC), which is a well-known hybrid EC with high cell voltage of ~4 V in non-aqueous electrolytes. [15][16][17] In our previous work, the proof-of-concept of AdHiCap was presented using chemically synthesized MnO2 with acetylene black (AB) as a conductive additive in a beaker-type flooded cell setup.…”

Aqueous Lithium-Air Rechargeable Batteries

“…7, where platinum with platinum black was used as the counter electrode. 21 The cell resistances increased only 10% over one month, which suggests excellent stability of the multilayer Li anode construction in aqueous solution. Using the same equivalent circuit in Fig.…”