“The development of safety and high-performance batteries is imperative,” said corresponding author Dr. Ning Li, researcher at Beijing Key Laboratory of Environmental Science and Engineering, School of Material Science and Engineering, Beijing Institute of Technology. “Currently, the utilization of Li-rich materials enables lithium-ion batteries to achieve an energy density of ~400 Wh/kg.”
Dr. Li explained that the high capacity of Li-rich materials is attributed to their unique anion-cation charge compensation mechanism.
“However, anion reaction is a double-edged sword, bringing high capacity at the same time can lead to decomposition of the cathode and electrolyte.” Dr. Li said. “To overcome these issues, surface modification can be applied to stabilize surface microstructure from erosion and gas evolution, and the elemental doping or novel structural design can be employed to stabilize the bulk structure during repeatedly de/lithiation.”
“In addition, the use of liquid electrolytes poses limitations as they cannot withstand high voltages, resulting in electrolyte decomposition and battery failure.” Dr. Li said. “Therefore, the safe and stable solid-state electrolytes with wide electrochemical window, are ideal choices to match with these high-performance cathode materials to achieve high-energy solid-state batteries.”
The cycling performance of Li-rich cathode is significantly enhanced, but the SSBs show the relatively low practical capacity. The challenge is the interfacial ion and electron transfer between Li-rich cathode and solid-state electrolyte.
“This review presents some ideas for dealing with the interfacial problem, firstly, the Li-rich cathode can be coated with robust and ionic-conductive surface layer to improve Li+ ion diffusion kinetics and inhibit unfavorable gas evolution. Secondly, it is beneficial to select solid-state electrolyte with a similar crystalline structure to Li-rich cathode to enhance interfacial stability and compatibility. Thirdly, interphase mediators can be applied between the electrode and electrolyte, such as organic surface modifiers or inorganic intercalation compounds to reduce interfacial side reactions and contact impedance. Lastly, increasing the interface contact area between the electrolyte and electrode, by using nanostructured electrode materials, can improve the ion transport rate and electrochemical performance of the battery,””Dr. Li said, “to develop high-performance and safe SSBs, the comprehensive approach by combining theoretical calculations and experimental validations is recommended, through considering various factors such as the battery’s performance, cost, and sustainability.”
Other contributors include Lifeng Xu, Shi Chen, Yuefeng Su, Jizhuang He, Lian Wang, Xing Shen, Lai Chen, Duanyun Cao, Yun Lu, Meng Wang, Liying Bao, and Feng Wu, all at the Beijing Key Laboratory of Environmental Science and Engineering, School of Material Science and Engineering, Beijing Institute of Technology.
The National Key R&D Program of China (2021YFC2902905), Beijing Nova Program, Chongqing Outstanding Youth Fund (2022NSCQ-JQX3895), Chongqing Talents Plan for Young Talents (CQYC202005032), The Key Project of Chongqing Technology Innovation and Application Development (2022TIAD-DEX0024), and the National Natural Science Foundation of China (22109010 and 552202205) supported this work.