Promises, Challenges, and Recent Progress of Inorganic Solid‐State Electrolytes for All‐Solid‐State Lithium Batteries

Abstract

All-solid-state lithium batteries (ASSLBs) have the potential to revolutionize battery systems for electric vehicles due to their benefits in safety, energy density, packaging, and operable temperature range. As the key component in ASSLBs, inorganic lithium-ion-based solid-state electrolytes (SSEs) have attracted great interest, and advances in SSEs are vital to deliver the promise of ASSLBs. Herein, a survey of emerging SSEs is presented, and ion-transport mechanisms are briefly discussed. Techniques for increasing the ionic conductivity of SSEs, including substitution and mechanical strain treatment, are highlighted. Recent advances in various classes of SSEs enabled by different preparation methods are described. Then, the issues of chemical stabilities, electrochemical compatibility, and the interfaces between electrodes and SSEs are focused on. A variety of research addressing these issues is outlined accordingly. Given their importance for next-generation battery systems and transportation style, a perspective on the current challenges and opportunities is provided, and suggestions for future research directions for SSEs and ASSLBs are suggested.

Nanostructured Metal–Organic Framework (MOF)‐Derived Solid Electrolytes Realizing Fast Lithium Ion Transportation Kinetics in Solid‐State Batteries

“…Solid‐state batteries constructed from solid electrolytes (SEs) attract ever growing attentions, because SEs offer high safety, and their excellent stability enables metallic Li anode and high‐voltage cathode, which results in high energy density . SEs for lithium batteries mainly fall into two categories of materials: ionic conducting ceramics and polymers .…”

“…SEs for lithium batteries mainly fall into two categories of materials: ionic conducting ceramics and polymers . However, SEs usually suffer from low ionic conductivity and huge resistances at the interfaces between SE and active electrodes . The ionic conductivities of polymers are below 10 −6 S cm −1 and their stabilities under high potentials is poor, even though they show low resistances at the electrode/electrolyte interfaces .…”

Charge compensation mechanisms in Li‐substituted high‐entropy oxides and influence on Li superionic conductivity

“…A promising direction is the use of solid state electrolytes, which would eliminate the need for liquid confinement and make the cells design simpler. The main difficulty is the development of solid state Li + conductors exhibiting Li conductivity comparable to that of liquid electrolytes close to room temperature …”

Flexible, Flame‐Resistant, and Dendrite‐Impermeable Gel‐Polymer Electrolyte for Li–O2/Air Batteries Workable Under Hurdle Conditions

“…Moreover, they can mechanically suppress the growth of dendritic Li and prevent the infiltration of moisture from air. However, the state‐of‐the‐art solid ceramic electrolytes suffer from several important drawbacks, such as low practical conductivity, difficult densification, instability under various conditions, poor electrolyte–electrode interfacial contact and poor mechanical flexibility, which seriously impede the practical applications of Li–O 2 /air batteries with ceramic electrolytes …”