The development of a new lithium-ion conducting ceramic textile could get us a step closer to practical solid-state lithium metal batteries
Lithium-ion batteries are found in everything from laptops and power tools, to electric cars and Mars rovers. They are relatively inexpensive, can be easily recharged, and operate well at low and ambient temperatures. But there are some limitations to the performance of today’s commercial lithium batteries – because they use flammable liquid or polymer electrolytes, they’re not suited for use at higher temperatures. And they have limited capacity and short lifespans.
Solid-state lithium metal batteries are predicted to overcome many of these limitations, prompting researchers to search for materials that offer lithium-ion conductivity and good electrochemical stability, and that can be processed at scale. The latest breakthrough in this effort comes from a team led by Dr Eric D. Wachsman at the University of Maryland. Published in the latest issue of Materials Today [DOI: 10.1016/j.mattod.2018.01.001], they report on a conductive, flexible, ceramic textile that can be used in a solid electrolyte for high-performance Li-metal batteries.
They fabricated their woven, fibrous structure by soaking a textile template, comprised of 10 µm-diameter microfibers, in a garnet-like ceramic precursor. The resulting structure combines a high surface area to volume ratio, to enable ionic conduction and electrochemical reactions, and the stability and Li-ion conductivity of a cubic crystalline conductor (Li7La3Zr2O1). The ceramic textile retained the flexibility of the original textile template, but, like carbon fibre in a resin matrix, also provided structural and electrical reinforcement for a solid polymer electrolyte in a solid-state battery architecture.
This composite-textile-electrolyte displayed a Li-ion conductivity of 2.7 x10-5 S/cm at 25°C and 1.8 x 10-4 S/cm at 60°C – an order of magnitude higher than that measured for the electrolyte alone. It also achieved stable long-term Li cycling (> 500 hours) without failure. In addition, the team explored the textile’s use as an electrolyte framework for 3D electrodes in lithium-sulphur batteries. They achieved ultrahigh cathode loading (10.8g/cm2 sulphur), and predict that with changes to the design, an energy density of 352 Wh/kg could be achievable – that would significantly exceed the performance of state-of-the-art Li-ion batteries.
The authors are confident that their fabrication procedures could be extended beyond the lab, saying “The simplicity, rapidity, and cost-saving characteristics of the template method….will make large-scale manufacturing possible. In addition, it may enable the development of ceramics with tailored compositions and structures.”
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Yunhui Gong, Kun Fu, Shaomao Xu, Jiaqi Dai, Tanner R. Hamann, Lei Zhang, Gregory T. Hitz, Zhezhen Fu, Zhaohui Ma, Dennis W. McOwen, Xiaogang Han, Liangbing Hu, Eric D. Wachsman, “Lithium-ion conductive ceramic textile: A new architecture forflexible solid-state lithium metal batteries” Materials Today, Article In Print, 2018. DOI: 10.1016/j.mattod.2018.01.001