Progress of Lithium-Ion Transport Mechanism in Solid-State Electrolytes

Authors

Bing-Kai Zhang, 1. School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen 518055, Guangdong, China;2. School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, Guangdong, China;
Lu-Yi Yang, 1. School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen 518055, Guangdong, China;
Shun-Ning Li, 1. School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen 518055, Guangdong, China;
Feng Pan, 1. School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen 518055, Guangdong, China;Follow

Corresponding Author

Feng Pan(panfeng@pkusz.edu.cn)

Abstract

Inorganic crystalline solid electrolytes exhibit exceptional room-temperature ionic conductivities, giving them the potential to enable all-solid-state lithium (Li) - ion batteries. Developing new high-performance electrolytes is one of the most critical challenges to realize solid-state batteries, which requires understanding how chemistry facilitates fast ionic conduction and what the Li-ion migration mechanism is in inorganic solid electrolytes. In this review, we aim to summarize recent fundamental research progress in Li-ion transport, including crystal structure, behavior of ion migration (i.e., single-ion jump and multi-ions cooperative migration), and the relationship between ion migration and microstructure.
Generally, ion transport in crystalline structure can be categorized into vacancy and non-vacancy mechanism. For Li-ion conduction, the migration can be achieved through single-ion hopping and collective diffusion mechanism. For single-ion hopping mechanism, the diffusivity is determined by the depth of potential well (activation energy) and lattice dynamics; whereas in the later mechanism Li-ion moving from high potential to low potential could partially offset the energy required for Li-ion moving from low potential to high potential. By studying the collective diffusion from the perspective of local structures, it is believed that collective diffusion in fast ion conductor originates from the local “dual Li-S/O” structure units, which can be characterized by the “nearest Li-Li distance”.
Next, the paradigm of ion transport in solids is summarized. It is pointed out that most ion conductors follow Meyer-Neldel rule, where the activation energy and pre-exponential factor are mutual compensating. As a result, a balance should be adapted between these two values to achieve high Li-ion conductivity. However, for some fast ion conductors, the relationship does not follow the Meyer-Neldel rule (i.e., anti-Meyer-Neldel rule). Therefore, the physical significance of anti-Meyer-Neldel rule should be understood to develop next-generation lithium ion conductors.
In the end, future perspectives and open questions are proposed to design and develop high-performance inorganic solid electrolytes.

Graphical Abstract

Keywords

solid-sate electrolytes, Li-ion transport mechanism, cooperative transport, structure-function relationship, Meyer-Neldel rule

DOI Link

https://doi.org/10.13208/j.electrochem.201244

Publication Date

2021-06-28

Online Available Date

2021-04-22

Revised Date

2021-04-19

Received Date

2021-02-01

Recommended Citation

Bing-Kai Zhang, Lu-Yi Yang, Shun-Ning Li, Feng Pan. Progress of Lithium-Ion Transport Mechanism in Solid-State Electrolytes[J]. Journal of Electrochemistry, 2021 , 27(3): 269-277.
DOI: 10.13208/j.electrochem.201244
Available at: https://jelectrochem.xmu.edu.cn/journal/vol27/iss3/8