Mg-based inorganic nanofibers constructing fast and multi-dimensional ion conductive pathways for all-solid-state lithium metal batteries

Solid‐state lithium metal batteries (SSLMBs) have attracted considerable attention as one of the most promising energy storage systems owing to their high safety and energy density. Solid electrolytes, particularly polymer‐based composite solid electrolytes (CSEs), are considered promising electrolyte candidates for SSLMBs. However, their wide application is inhibited by various electrochemical issues, such as low ionic conductivity, the growth of lithium dendrites, and poor cycling stability, which are related to interface issues within SSLMBs. In this review, the parameters related to various interfaces in the CSE of SSLMBs, including the interfaces between the polymer matrix and inorganic fillers, between the CSEs and the cathode, and between the CSEs and the lithium metal anode, are examined. Relevant issues and corresponding remediation strategies are proposed. Finally, future perspectives based on interfacial engineering and the characterization of polymer/inorganic filler interactions are proposed for building high‐performance CSEs for use in SSLMBs.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/sus2.67

Interface science in polymer‐based composite solid electrolytes in lithium metal batteries

Low-cost and flexible solid polymer electrolytes are promising in all-solid-state Li-metal batteries with high energy density and safety. However, both the low room-temperature ionic conductivities and the small Li+ transference number of these electrolytes significantly increase the internal resistance and overpotential of the battery. Here, we introduce Gd-doped CeO2 nanowires with large surface area and rich surface oxygen vacancies to the polymer electrolyte to increase the interaction between Gd-doped CeO2 nanowires and polymer electrolytes, which promotes the Li-salt dissociation and increases the concentration of mobile Li ions in the composite polymer electrolytes. The optimized composite polymer electrolyte has a high Li-ion conductivity of 5 × 10−4 S cm−1 at 30 °C and a large Li+ transference number of 0.47. Moreover, the composite polymer electrolytes have excellent compatibility with the metallic lithium anode and high-voltage LiNi0.8Mn0.1Co0.1O2 (NMC) cathode, providing the stable cycling of all-solid-state batteries at high current densities. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/eem2.12272

Optimized CeO <sub>2</sub> Nanowires with Rich Surface Oxygen Vacancies Enable Fast Li‐Ion Conduction in Composite Polymer Electrolytes

Li metal batteries (LMBs) have attracted widespread attention in recent years because of their high energy densities. But traditional LMBs using liquid electrolyte have potential safety hazards, such as: leakage and flammability. Replacing liquid electrolyte with solid polymer electrolyte (SPE) can not only significantly improve the safety, but also improve the energy density of LMBs. However, till now, there is only limited success in improving the various physical and chemical properties of SPE, especially in thickness, posing great obstacles to further promoting its fundamental and applied studies. In this review, the authors mainly focus on evaluating the merits of ultrathin SPE and summarizing its existing challenges as well as fundamental requirements for designing and manufacturing advanced ultrathin SPE in the future. Meanwhile, the authors outline existing cases related to this field as much as possible and summarize them from the perspective of synthetic chemistry, hoping to provide a comprehensive understanding and serve as a strategic guidance for designing and fabricating high‐performance ultrathin SPE. Challenges and opportunities regarding this burgeoning field are also critically evaluated at the end of this review.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/advs.202205233

Ultrathin Solid Polymer Electrolyte Design for High‐Performance Li Metal Batteries: A Perspective of Synthetic Chemistry

All‐solid‐state Li batteries (ASSLBs) are considered suitable candidates to replace conventional batteries utilizing liquid electrolytes. However, the applications of this type of batteries are limited owing to their narrow operating temperature range, low ionic conductivity, poor long‐term stability, and complex production process. Herein, a simple approach that combines all potential battery candidates that have been investigated over the last few years, including polyethylene oxide (PEO), Li7La3Zr2O12 (LLZO), succinonitrile (SN), and Li salt (LiTFSI), is employed to solve the limitations of ASSLBs. LLZO codoped with Al3+ and Nb5+ (NAL) is synthesized at a low temperature using a modified sol‐gel Pechini method. NAL, along with SN, plays a critical role in improving the performance of the resultant solid polymer electrolyte, which can be operated at room temperature. The integrated electrolyte PEO/LiTFSI‐SN‐NAL (PLS‐NAL) delivers a high ionic conductivity of 3.09 × 10−4 S cm−1 and an excellent Li‐ion transference number of 0.75 at room temperature. ASSLBs combining LiFePO4 and PLS‐NAL exhibit excellent cycling stability at both room temperature and 45 °C with a high capacity retention of ≈90% after 200 cycles and cycle life of up to 400 cycles.

Nan Meng

Papers

Particles in composite polymer electrolyte for solid-state lithium batteries: A review