An air-stable and waterproof lithium metal anode

An air-stable and waterproof lithium metal anode
Diagram of the Li-wax-PEO and its stability in the air and water. Credit: Science China Press

Lithium metal anode offers a promising pathway to upgrade the energy density of lithium ion batteries for its high specific capacity (3800 mAh g-1) and low voltage (-3.04 V vs. Li/Li+). But the safety issues caused by dendrite growth and instability in air caused by its high chemical activity limit its large-scale use as an electrode material. Lithium metal is highly sensitive to moisture and oxidative components in the air, leading to the generation of insulating products like lithium hydroxides on its surface and the resultant deterioration of the electrochemical performance. Moreover, when lithium contacts water, combustion and explosion can occur due to the production of hydrogen and heat. The sensitivity of lithium metal therefore necessitates demanding requirements for the transport, storage and process of lithium metal anode. It is hence highly desirable to develop an air-stable and waterproof lithium metal anode for potential use in the future.

In the electronics field, packaging technologies protect from and corrosion in humid air and water with a coating, which provides design impetus for the protection of lithium metal. Recently, a research team led by Prof. Quan-Hong Yang in Tianjin University and Prof. Wei Lv in Tsinghua University developed a wax-PEO coating for lithium metal surfaces utilizing a simple dip coating method to realize an air-stable and waterproof . Wax as a commonly-used inert sealing material is easily coated on the surface of lithium metal. This wax-based composite coating prevents adverse reactions of lithium metal in air and water. In batteries, the coating retards the etching of electrolyte to the surface of lithium metal anodes while the homogeneously distributed PEO guarantees uniform lithium ion conduction at the interface and inhibits the growth of lithium dendrites.

Under the protection of wax-PEO coating, lithium surfaces remain unchanged in air with high relative humidity of 70% for 24 hours, and high capacity retention of 85% is achieved. Even contacting lithium with water immediately, no combustion or capacity decay occurred. The coated lithium metal anode remains stable for as long as 500 hours in symmetric cells, and lithium sulfur batteries assembled with the coated lithium metal anode show a low capacity decay rate of 0.075% per cycle for 300 cycles. This work demonstrates an efficient packaging technology for air-stable and waterproof anodes. It is also easily scalable and applicable to other sensitive electrode materials.

An air-stable and waterproof lithium metal anode
Electrochemical performances of Li-wax-PEO and Li in symmetric cells and lithium sulfur batteries. Credit: Science China Press

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More information: Yunbo Zhang et al, An air-stable and waterproof lithium metal anode enabled by wax composite packaging, Science Bulletin (2019). DOI: 10.1016/j.scib.2019.05.025
Citation: An air-stable and waterproof lithium metal anode (2019, July 19) retrieved 22 August 2019 from https://phys.org/news/2019-07-air-stable-waterproof-lithium-metal-anode.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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Jul 19, 2019
This isn't actually safer, it merely prevents immediate failure.

If the battery gets compromised by heat or mechanical damage, the lithium is still going to catch fire and react with air and water and simply evaporate the wax coating away.

Jul 21, 2019
Thinking in Mega Levels will help; Equator has maximum Sun Exposure over the oceans. Sun moves from East to West. So, Global Collection of DISCHARGED Mega Solar Cells from the Governments/Electric Grids of those locations & moving them over oceans along with Sun...Then, Disposing the Fully Charged ones there for their use, meanwhile collecting their locally Discharged Solar Cells. Such Relentless Inter-Government Collaboration will help. They can also Sell/Distribute Charged Batteries to nearby Ships on oceans for their use ! Equator passes through 13 countries: Ecuador, Colombia, Brazil, Sao Tome & Principe, Gabon, Republic of the Congo, Democratic Republic of the Congo, Uganda, Kenya, Somalia, Maldives, Indonesia and Kiribati
http://tldesigner...h-wit-1/

Jul 21, 2019
Thinking in Mega Levels will help; Equator has maximum Sun Exposure over the oceans. passes through 13 countries

This List needs correction from More Knowledgeable Persons in this field.
Away From Equator:
Korea (GMT+9)
Australia, 1728 miles South of Equator (GMT+8)
Hawaii, 1375 miles North of Equator (GMT-10)
Over The Equator:
Indonesia (GMT+7)
Equatorial Guinea (GMT+1)
Equador (GMT-5)

Jul 21, 2019
Thinking in Mega Levels will help; Equator has maximum Sun Exposure over the oceans. passes through 13 countries

Kiribati, which is in between Ecuador & Indonesia exhibits (GMT+12),(GMT+13)&(GMT+14)

Jul 22, 2019
Tesla Giga Factory intends to be the biggest building in the entire world once it finishes with the remaining 70%. Rather, Tesla should have its Gigafactories at Sea Ports and the Battery Carrying Ships should start in the morning with a load of Discharged batteries to exchange them post-charging to those that have started at night times. The Batteries will both run those ships and also are delivered to the needy electrical grids nearby, if any !
https://www.tesla...afactory

Jul 23, 2019
I Envisage humongous Commercial Ships with their edges decorated with 'tree branches'- like Strong Solar Panels & their Insides partially filled with fuel energy storage systems. They should exchange their well-charged cells with ships that they happen to meet that are running out of them because of their hitherto travel in dark !

Jul 23, 2019
Sun is over Americas for only less than 12 hrs. Americas are surrounded by Sea water just like rest of the continents. So, Ships should go around Americas and distribute their Charged Fuel Cells to the Electric Grids nearby. But what about the other 12 hrs? The ships coming from left and right should dispose of their Charged cells for them !

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