With the rapid advancement of electric vehicles, energy storage systems, and consumer electronics, a demand for high-performance lithium-ion batteries (LIBs) is escalating. The electrolyte plays a pivotal role in affecting the battery performance, safety, and longevity. Liquid electrolytes, which are widely used in commercial LIBs, offer high ionic conductivity and ease of processing. However, solid electrolyte interphase (SEI) formed in liquid electrolyte systems degrades during repeated charge-discharge cycles, increasing impedance, reducing the Coulombic efficiency, and compromising cycling stability. In contrast, solid-state electrolytes, known for their potential to enhance battery safety, face some challenges such as lower ion conductivity, poor mechanical properties, and difficulties in maintaining stable electrode interfaces under operational conditions.

The electrolyte-electrode interface, particularly at anode, is crucial for lithium battery performance. Lithium dendrite growth is a primary concern as it can cause short circuits and battery failure. In liquid electrolyte systems, dendrite formation is accelerated by uneven ion flow, SEI instability, and excessive current density. Solid-state electrolytes, while promising in terms of theoretical safety, also face some challenges, i.e., slower ion conductivity at room temperature and poor interface stability with lithium metal anodes. A better understanding of these differences is crucial for advancing electrolyte design.

One of the key challenges for liquid electrolytes is to control SEI formation. The chemical composition and morphology of the SEI directly impact the battery performance. A thick or uneven SEI layer increases internal resistance and slows ion flow, thereby reducing the Coulombic efficiency and cycle stability. In solid-state systems, the solid-solid interface between the electrolyte and electrode material leads to a high interfacial resistance, restricting ion migration and affecting charge-discharge efficiency. Ion transport in solid-state electrolytes is also more uneven and slower, further compromising safety. While SEI formation in liquid electrolytes can suppress dendrite growth and promote uniform lithium deposition, solid-state electrolytes tend to exhibit a higher interfacial resistance, which accelerates dendrite growth and leads to short circuits. These distinct interface properties are the main cause of the performance gap between liquid and solid-state batteries.

Optimizing interface stability and ion flow uniformity in both liquid and solid-state electrolytes is essential for improving battery technology. In this review, the characteristics of the anode interface in both systems are compared, with a focus on lithium dendrite growth mechanisms. Some factors like ion conductivity, electrode-electrolyte interactions, and interface stability that affect electrochemical performance are mentioned. This review also analyzes strategies to optimize electrolyte interface stability and ion flow uniformity in both liquid-state and solid-state systems. Electrolyte design strategies based on ion flow regulation to enhance ion conductivity, reduce interfacial resistance, and ensure more uniform ion distribution are proposed. These strategies include the development of advanced electrolyte materials, interface engineering to improve ion transport, and the use of hybrid systems that combine the advantages of both liquid and solid electrolytes.