An Intermediate-Temperature High-Performance Na-ZnCl2 Battery

Xiaochuan Lu; Hee Jung Chang; Jeffery F Bonnett; Nathan L Canfield; Keeyoung Jung; Vincent L Sprenkle; Guosheng Li

doi:10.1021/acsomega.8b02112

An Intermediate-Temperature High-Performance Na-ZnCl₂ Battery

ACS Omega. 2018 Nov 16;3(11):15702-15708. doi: 10.1021/acsomega.8b02112. eCollection 2018 Nov 30.

Authors

Xiaochuan Lu¹, Hee Jung Chang¹, Jeffery F Bonnett¹, Nathan L Canfield¹, Keeyoung Jung², Vincent L Sprenkle¹, Guosheng Li¹

Affiliations

¹ Electrochemical Materials and Systems Group, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
² Materials Research Division, Research Institute of Industrial Science & Technology, Pohang 790-330, South Korea.

Abstract

The Na-β-alumina battery (NBB) is one of the most promising energy storage technologies for integrating renewable energy resources into the grid. In the family of NBBs, Na-NiCl₂ battery has been extensively studied during the past decade because it has a lower operating temperature, better safety, and good battery performance. One of the major issues with the Na-NiCl₂ battery is material cost, which is primarily from Ni metal in the battery cathode. As an alternative, Zn is much cheaper than Ni, and replacing Ni with Zn in the cathode can significantly reduce the cost. In this work, we investigate the performance and reaction mechanism for a Na-ZnCl₂ battery at 190 °C. Two-step reversible reactions are identified. During the first step of charging, NaCl reacts with Zn to produce a ribbon-type Na₂ZnCl₄ layer. This layer is formed at the NaCl-Zn interface rather than covering the surface of the Zn particles, which leads to an excellent cell rate capability. During the second step, the produced Na₂ZnCl₄ is gradually consumed to form ZnCl₂ on the surface of Zn particles. The formed ZnCl₂ covers most of the surface area of the Zn particles and shows a limited rate capability compared to that of the first step. We conclude that this limited performance of the second step is due to the passivation of Zn particles by ZnCl₂, which blocks the electron pathway of the NaCl-Zn cathodes.