Integrating a redox-coupled dye-sensitized photoelectrode into a lithium–oxygen battery for photoassisted charging

Abstract

With a high theoretical specific energy, the non-aqueous rechargeable lithium-oxygen battery is a promising next-generation energy storage technique. However, the large charging overpotential remains a challenge due to the difficulty in electrochemically oxidizing the insulating lithium peroxide. Recently, a redox shuttle has been introduced into the electrolyte to chemically oxidize lithium peroxide. Here, we report the use of a triiodide/iodide redox shuttle to couple a built-in dye-sensitized titanium dioxide photoelectrode with the oxygen electrode for the photoassisted charging of a lithium-oxygen battery. On charging under illumination, triiodide ions are generated on the photoelectrode, and subsequently oxidize lithium peroxide. Due to the contribution of the photovoltage, the charging overpotential is greatly reduced. The use of a redox shuttle to couple a photoelectrode and an oxygen electrode offers a unique strategy to address the overpotential issue of non-aqueous lithium-oxygen batteries and also a distinct approach for integrating solar cells and batteries.

Direct Solar Charging of an Organic–Inorganic, Stable, and Aqueous Alkaline Redox Flow Battery with a Hematite Photoanode

“…Some of the challenges encountered then were lack of efficient, stable and cost‐efficient photoelectrodes and issues with membrane selectivity 5. Recently, the advantages of photo‐assisted charging of a lithium and iodide based battery has been demonstrated using a dye‐sensitized TiO 2 photoelectrode, and direct photoelectrochemical response has been shown with TiO 2 and an all vanadium aqueous and acidic RFB 6. Given the broad band gap of TiO 2 (3.2 eV) and the instability of most well‐studied metal oxide semiconductors in acidic electrolytes, the applications of photoelectrodes with existing aqueous RFB technologies are limited.…”

A high energy density solar rechargeable redox battery

“…These devices are in fact similar to back-toback fabricated solar cell-battery structures and their working mechanism involves similar energy conversion steps as in the individual solar cells and batteries. [3][4][5][6] Aer illumination, electrons are pumped into the TiO 2 conduction band, travel through the external circuitry and reduce the active materials at the end electrode (bottom). Meanwhile in the DSSC, redox species are oxidized on the photo-electrode (top) and reduced at the center electrode.…”

Inorganic & organic materials for rechargeable Li batteries with multi-electron reaction

“…To decrease the charge potential, some soluble catalysts such as tetrathiafulvalene (TTF), LiI, and iron phthalocyanine (FePc) are proposed [128][129][130][131]. Compared with solid catalysts, the soluble catalysts are more advantageous to catalyze the decomposition of Li 2 O 2 .…”

“…The charge plateau could maintain at 3.5 V during 100 cycles at 1 mA cm -2 . Wu's group [131] reported the use of an I 3 -/I -redox couple to combine the photoelectrode of dye-sensitized solar cells with the oxygenelectrode Li-O 2 batteries. Through utilizing solar energy, the charge plateau decreased to 3.4 V at 0.032 mA cm -2 .…”