Improving cathode designs for solid-state lithium batteries with high energy density

Rechargeable liquid lithium-ion batteries are ubiquitous in consumer electronics, but their potential instability and low energy density make them ill-suited for grid-scale energy storage. Solid-state lithium batteries have the potential to solve both of these issues with increased safety and a much higher energy density. However, the technology is limited by the low mass loading of the cathode.

Sun et al. overcame this limitation with 3D current collectors and in situ solidification of polymer electrolytes. Their method increases the cathode mass loading and improves performance.

“Compared with the traditional cathodes, the newly designed cathodes show composite ionic-electronic conducting channels and excellent cathode/electrolyte interface contacts, which lead to the high discharge capacities for solid-state lithium batteries,” said author Zhijie Bi.

In typical solid-state batteries, cathode mass loading is limited by charge transfer kinetics. Increasing the active cathode mass is generally related to reduced charge transfer capability, an unacceptable tradeoff. The authors took inspiration from liquid battery designs to create a cathode that achieves both aims.

In the team’s design, the current collector works as a framework to guide the adsorption of cathode material and control the mass loading. The in situ solidified polymer electrolytes are used to create ion-conducting channels inside the cathodes, facilitating charge transfer. The overall structure of the cathode enables high energy densities and rapid charging and discharging.

The authors are planning to further improve their design by incorporating high-mass-loading cathodes with organic-inorganic composite electrolytes, which minimize the weight and volume of inactive components.

“Organic-inorganic composite electrolytes with small thickness and weight are more suitable for high-energy-density solid-state batteries than the inorganic ceramic electrolytes,” said Bi.

Source: “Combination of 3D current collectors and in-situ polymerized electrolytes enabling high-mass-loading cathodes for solid-state lithium batteries,” by Qifu Sun, Muhammad Khurram Tufail, Wenkai Li, Ning Zhao, Zhijie Bi, and Xiangxin Guo, Applied Physics Letters (2023). The article can be accessed at https://doi.org/10.1063/5.0147529 .