H3PO4-Induced Nano-Li3PO4 Pre-reduction Layer to Address Instability between the Nb-Doped Li7La3Zr2O12 Electrolyte and Metallic Li Anode

Jiawen Tang; Yajun Niu; Yongjian Zhou; Shuqing Chen; Yan Yang; Xiao Huang; Bingbing Tian

doi:10.1021/acsami.2c21133

H₃PO₄-Induced Nano-Li₃PO₄ Pre-reduction Layer to Address Instability between the Nb-Doped Li₇La₃Zr₂O₁₂ Electrolyte and Metallic Li Anode

ACS Appl Mater Interfaces. 2023 Feb 1;15(4):5345-5356. doi: 10.1021/acsami.2c21133. Epub 2023 Jan 19.

Authors

Jiawen Tang¹, Yajun Niu¹, Yongjian Zhou¹, Shuqing Chen¹, Yan Yang², Xiao Huang¹, Bingbing Tian¹

Affiliations

¹ International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen518060, China.
² Collaborative Innovation Center for Vessel Pollution Monitoring and Control, Dalian Maritime University, Dalian116026, China.

PMID: 36657037
DOI: 10.1021/acsami.2c21133

Abstract

Solid-state batteries based on a metallic Li anode and nonflammable solid electrolytes (SEs) are anticipated to achieve high energy and power densities with absolute safety. In particular, cubic garnet-type Nb-doped Li₇La₃Zr₂O₁₂ (Nb-LLZO) SEs possess superior ionic conductivity, are feasible to prepare under ambient conditions, have strong thermal stability, and are of low cost. However, the interfacial compatibility with Li metal and Li dendrite hazards still hinder the applications of Nb-LLZO. Herein, a quick and efficient solution was applied to address this issue, generating a nano-Li₃PO₄ pre-reduction layer from the reaction of H₃PO₄ with the ion-exchanged passivation layer (Li₂CO₃/LiOH) on the surface of Nb-LLZO. A lithiophilic, electrically insulating interlayer is in situ created when the Li₃PO₄ modified layer interacts with molten Li, successfully preventing the reduction of Nb⁵⁺. The interlayer, which mostly consists of Li₃P and Li₃PO₄, also has a high shear modulus and relatively high Li⁺ conductivity, which effectively inhibit the growth of Li dendrites. The Li|Li₃PO₄|Nb-LLZO|Li₃PO₄|Li symmetric cells stably cycled for over 5000 h at 0.05 mA cm^-2 and over 1000 h at a high rate of 0.15 mA cm^-2 without any short circuits. The LiFePO₄ and S/C hybrid solid-state batteries using the modified Nb-LLZO electrolyte also demonstrated good electrochemical performances, confirming the practical application of this interfacial engineering in various solid-state battery systems. This work offers an efficient solution to the instability issue between the Nb-LLZO SE and metallic Li anode.

Keywords: Li metal solid-state battery; Li3PO4; Nb-doped Li7La3Zr2O12 (Nb-LLZO); conversion reaction; interfacial reduction.