Materials Design for Fast Charging: Developments and Challenges in Li-Ion Batteries

Lithium-ion batteries (LIBs) have changed portable electronic devices and are essential in the ongoing green strategies for renewable energy storage. As demands for faster charging capabilities increase, particularly in electric vehicles (EVs), the limitations of current LIB technologies become apparent. In this review, exploring the challenges and recent technological developments in designing materials for fast-charge lithium-ion batteries can give a better understanding of rate-limiting factors and new technological breakthroughs to increase the charging rate. Current studies that endeavor to promote the quick-charging feature of cathode materials primarily focus on creating conductive pathways and eliminating the long lithium-ion diffusion pathways. Cathode materials have been considerably enhanced through nanostructure and surface changes, which have led to greater Li-ion diffusion and higher structural stability. Novel materials like high-nickel content cathodes (e.g., NMC811) have demonstrated better energy density, while lithium-rich layered oxides and high-voltage spinel structures (e.g., LiNi0.5Mn1.5O4) showed promising fast charging characteristics, which are the key parameters that clarify the fast-charging capabilities. However, issues exist in controlling capacity fade and ensuring long-term structural stability under high-rate current. Silicon-carbon composites are considered an alternative for anode materials, providing increased capacity and reducing silicon's volume expansion problem. Lithium titanate (Li4Ti5O12) anodes have gained attraction due to their high theoretical capacity, cycling stability, and fast charging capability. The issue remains in combining high capacity, fast charging ability, and long-term stability. In terms of electrolytes, the diffusion coefficient of Li+ ions in liquid electrolytes becomes more significant than in solid electrodes. Highly concentrated electrolytes (HCEs) showed increased oxidative stability and fewer side reactions; Ionic liquid-based electrolytes demonstrate potential with their large electrochemical windows and enhanced thermal stability. Solid electrolytes, both ceramic and polymer-based, are getting towards practical applications. However, challenges such as increased viscosity for HCEs, economic considerations for ionic liquids, and low lithium-ion conductivity for solid electrolytes remain.