{"id":7817,"date":"2013-06-06T06:12:00","date_gmt":"2013-06-06T13:12:00","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=7817"},"modified":"2013-06-06T06:12:00","modified_gmt":"2013-06-06T13:12:00","slug":"stanford-scientists-develop-high-efficiency-zinc-air-battery","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/stanford-scientists-develop-high-efficiency-zinc-air-battery\/","title":{"rendered":"Stanford scientists develop high-efficiency zinc-air battery"},"content":{"rendered":"

Battery researchers, including those at Stanford University, have been focusing for years on improving lithium batteries of multiple chemistries.\u00a0 While IBM tries to create the 500-mile battery<\/a> based on lithium-air reactions, and ReVolt<\/a> in Portland works on perfecting a long-lasting zinc-air cell, Stanford researcher Hongjie Dai and his team claim to have \u201cdeveloped an advanced zinc-air battery with higher catalytic activity and durability than similar batteries made with costly platinum and iridium catalysts.\u201d<\/p>\n

The resulting battery, detailed in the May 7 online edition of the journal\u00a0Nature Communications<\/em><\/a>, could be the forerunner of something with greater endurance and lower cost than current efforts.<\/p>\n

Mark Schwartz, writing for Stanford<\/a>, quotes Dai, a professor of chemistry at the University and lead author of the study: “There have been increasing demands for high-performance, inexpensive and safe batteries for portable electronics, electric vehicles and other energy storage applications.\u00a0 Metal-air batteries offer a possible low-cost solution.”<\/p>\n

Lithium-ion batteries, despite their limited energy density (energy stored per unit volume), high cost and safety problems, have received the most attention, says Dai, but notes that \u201cmetal-air batteries have drastically higher theoretical energy density than either traditional aqueous batteries or lithium-ion batteries,” with zinc-air having the highest energy payoff for a relatively low cost.<\/p>\n

Zinc-air batteries combine atmospheric oxygen and zinc metal in a liquid alkaline electrolyte to generate electricity with a byproduct of zinc oxide. \u00a0When the process is reversed during recharging, oxygen and zinc metal are regenerated.<\/p>\n

\"\"<\/a>

Stanford’s zinc-air battery, a rechargeable zinc-oxide battery in a tri-electrode configuration with cobalt-oxide\/carbon nanotube and iron-nickel\/layered double hydroxide catalysts for charge and discharge, respectively. Image: Yanguang Li, Stanford University<\/p><\/div>\n

Metal-air batteries with aqueous electrolytes can be inherently safe, a major advantage considering the critical monitoring necessary for lithium cells.<\/p>\n

Usually catalytic reactions during charge and discharge are \u201csluggish\u201d on zinc-air batteries.\u00a0 Dai\u2019s group developed a number of Active and durable electrocatalysts on the air electrode are required to catalyze the oxygen-reduction reaction during discharge and the oxygen-evolution reaction during recharge. In zinc-air batteries, both catalytic reactions are sluggish, Dai said.<\/p>\n

Recently, his group has developed a number of \u201chigh-performance electrocatalysts made with non-precious metal oxide or nanocrystals hybridized with carbon nanotubes. These catalysts produced higher catalytic activity and durability in alkaline electrolytes than catalysts made with platinum and other precious metals.\u201d<\/p>\n

“\u2019We found that similar catalysts greatly boosted the performance of zinc-air batteries,\u2019 Dai said. \u2018A combination of a cobalt-oxide hybrid air catalyst for oxygen reduction and a nickel-iron hydroxide hybrid air catalyst for oxygen evolution resulted in a record high-energy efficiency for a zinc-air battery, with a high specific energy density more than twice that of lithium-ion technology.\u2019”<\/p>\n

The battery shows good reversibility and stability over weeks\u2019 long charge and discharge cycles. Despite the encouraging results, Dai notes \u201cchallenges\u201d with the zinc electrode and the aqueous electrolytes.<\/p>\n

Still, intrinsic safety and increased capacity are reasons to go forward.<\/p>\n

Other authors of the\u00a0Nature Communications<\/em>\u00a0study are Yanguang Li (lead author), Ming Gong, Yongye Liang, Ju Feng, Ji-Eun Kim, Hailiang Wang, Guosong Hong and Bo Zhang of the Stanford Department of Chemistry.<\/p>\n

The study was supported by Intel, a Stanford Global Climate and Energy Project exploratory program and a Stinehart\/Reed Award from the Stanford Precourt Institute for Energy.<\/p>\n

While the Stanford press release avoids sharing numerical data, the abstract for the Nature Communications paper gives a few hints as to how good the zinc-air battery might be.<\/p>\n

\u201cPrimary and rechargeable Zn-air batteries could be ideal energy storage devices with high energy and power density, high safety and economic viability. Active and durable electrocatalysts on the cathode side are required to catalyse oxygen reduction reaction during discharge and oxygen evolution reaction during charge for rechargeable batteries. Here we developed advanced primary and rechargeable Zn-air batteries with novel\u00a0CoO\/carbon\u00a0nanotube hybrid\u00a0oxygen\u00a0reduction catalyst and\u00a0Ni-Fe-layered double hydroxide\u00a0oxygen\u00a0evolution catalyst for the cathode. These catalysts exhibited higher catalytic activity and durability in concentrated alkaline electrolytes than precious metal\u00a0Pt\u00a0and\u00a0Ir\u00a0catalysts. The resulting primary Zn-air battery showed high discharge peak power density ~265\u2009mW\u2009cm\u22122<\/sup>, current density ~200\u2009mA\u2009cm\u22122<\/sup>\u00a0at 1\u2009V and energy density >700\u2009Wh\u2009kg\u22121<\/sup>. Rechargeable Zn-air batteries in a tri-electrode configuration exhibited an unprecedented small charge\u2013discharge voltage polarization of ~0.70\u2009V at 20\u2009mA\u2009cm\u22122<\/sup>, high reversibility and stability over long charge and discharge cycles.\u201d<\/p>\n

Those wishing to see the full paper can lower their net worth $32 for the privilege.<\/p>\n