Design Of Solid-state Electrolytes Research Articles

Reclaiming Neglected Compounds as Promising Solid State Electrolytes by Predicting Electrochemical Stability Window with Dynamically Determined Decomposition Pathway

AbstractThe accurate prediction of the electrochemical stability windows (ESWs) enables the rational design of solid state electrolytes (SSEs). Currently, the ESW prediction is based on direct and indirect decomposition analysis methods (DDAM and IDAM). However, DDAM/IDAM can only involve thermodynamically/kinetically favorable decomposition pathway, both resulting in the large deviation between the predicted ESW and the experimental one. Specifically, certain excellent candidate SSEs may be continuously neglected in the high‐throughput screening due to underpredicted ESWs. Herein, a high‐accuracy ESW prediction method is proposed enabling dynamical determination of the appropriate decomposition pathway by analyzing the electronic conductivities of all direct and indirect decomposition products. Following this, a high‐throughput computation is performed on the ESWs of 328 possible fast Li‐ion conductors with low ionic migration energy barriers from the previous research, obtaining good agreement with the available experimental results (Li10GeP2S12 and Li7La3Zr2O12). Furthermore, six previously neglected fluorides exhibiting ESWs over 4 V, oxidation potentials exceeding 6 V, excellent phase stability, and interfacial compatibility with seven typical cathodes are reclaimed as promising SSEs. This work demonstrates a strategy to accelerate the SSE development by improving the accuracy of the ESW prediction and enlarging the database of promising SSEs.

Ionic Conductivity of LiSiON and the Effect of Amorphization/Heterovalent Doping on Li+ Diffusion

The search for and design of suitable superior lithium ion conductors is a key process for developing solid state batteries. In order to realize a large range of applications, we researched the ionic conductivity of LiSiON, an example oxynitride mainly composed of elements with high abundance and a similar mixed anion size. Both its amorphous and heterovalent-doped phases were studied through density functional theory simulations. The Li+ ion diffusion behaviors and related properties are discussed. These elements are abundant in nature, and we found that amorphization or doping with P obviously enhanced the ionic conductivity of the system. General strategies to improve the kinetic properties of a candidate structure are presented, to help in the design of solid state electrolytes for lithium batteries.

Identifying descriptors for Li+ conduction in cubic Li-argyrodites via hierarchically encoding crystal structure and inferring causality

Identifying descriptors linked to Li+ conduction enables rational design of solid state electrolytes (SSEs) for advanced lithium ion batteries, but it is hindered by the diverse and confounding descriptors. To address this, by integrating global and local effects of Li+ conduction environment, we develop a generic method of hierarchically encoding crystal structure (HECS) and inferring causality to identify descriptors for Li+ conduction in SSEs. Taking the cubic Li-argyrodites as an example, 32 HECS-descriptors are constructed, encompassing composition, structure, conduction pathway, ion distribution, and special ions derived from the unit cell information. Partial correlation analysis reveals that the smaller anion size plays a significant role in achieving lower activation energy, which results from the competing effects between the lattice space and bottleneck size controlled by framework site disorder. Moreover, the promising candidates are suggested, in which Li6-xPS5-xCl1+x (e.g., Li5.5PS4.5Cl1.5 with the room ionic conductivity of 9.4mS cm−1 and the activation energy of 0.29eV) have been experimentally evaluated as excellent candidates for practical SSEs and the rest are novel compositions waiting for validation. Our work establishes a rational correlation between the HECS-descriptors and Li+ conduction and the proposed approach can be extended to other types of SSE materials.