Lithium Oxalate as a Lifespan Extender for Anode-Free Lithium Metal Batteries

Chen-Jui Huang; Ya-Ching Hsu; Kassie Nigus Shitaw; Yu-Jhen Siao; She-Huang Wu; Chia-Hsin Wang; Wei-Nien Su; Bing Joe Hwang

doi:10.1021/acsami.2c04693

Lithium Oxalate as a Lifespan Extender for Anode-Free Lithium Metal Batteries

ACS Appl Mater Interfaces. 2022 May 31. doi: 10.1021/acsami.2c04693. Online ahead of print.

Authors

Chen-Jui Huang^{1

2}, Ya-Ching Hsu^{1

2}, Kassie Nigus Shitaw^{1

2}, Yu-Jhen Siao^{1

2}, She-Huang Wu^{2

3}, Chia-Hsin Wang⁴, Wei-Nien Su^{2

3}, Bing Joe Hwang^{1

2

4}

Affiliations

¹ Nano-electrochemistry Laboratory, Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
² Sustainable Energy Development Center, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
³ Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
⁴ National Synchrotron Radiation Research Center (NSRRC), Hsinchu 300, Taiwan.

PMID: 35639111
DOI: 10.1021/acsami.2c04693

Abstract

Anode-free lithium metal batteries (AFLMBs) have been extensively studied due to their intrinsic high energy and safety without a metallic Li anode in cell design. Yet, the dendrite and dead-Li buildup continuously consumes the active Li upon cycling, leading to the poor lifespan of AFLMBs. Here, we introduce lithium oxalate into the cathode as an electrode additive providing a Li reservoir to extend the lifespan of AFLMBs. The AFLMB using 20% lithium oxalate and a LiNi_0.3Co_0.3Mn_0.3O₂ composite cathode exhibits >80 and 40% capacity retention after 50 and 100 cycles, respectively, outperforming the poor cycle life of fewer than 20 cycles obtained from the cell using a pure LiNi_0.3Co_0.3Mn_0.3O₂ cathode. Surprisingly, the average Coulombic efficiency of AFLMBs is found to improve as the amount of lithium oxalate increases in the composite cathode. This abnormal phenomenon could be attributed to the as-formed carbon dioxide after the first activation cycle forming a Li₂CO₃-rich solid-electrolyte interphase and improving the Li deposition and stripping efficiency. The findings in this work provide a new strategy to delay the capacity roll-over of AFLMBs from an electrode engineering perspective, which can be coupled with other approaches such as functional electrolytes synergistically to further improve the cycle life of AFLMBs for practical application.

Keywords: anode-free; layered compounds; lithiation; lithium metal batteries; lithium oxalate.