LiFePO₄ (LFP) cathodes present a promising ‘green’ alternative for lithium-ion batteries (LIBs), providing a reduced environmental footprint due to the absence of cobalt and nickel. With a maximum theoretical capacity of 170 mA h g-1, LFP cathodes have lower energy density than common NMC (LiNixMnyCo1-x-yO2) cathodes but are valued for their high thermal stability, long lifespan, non-toxicity, and low cost [1-3]. To enhance the overall capacity, safety, and sustainability of LFP-based LIBs, these cathodes can be paired with silicon as the anode material. Silicon offers one of the highest theoretical specific capacities of any anode material (3579 mA h g-1) and is an abundant, safe, inexpensive resource [4,5]. However, silicon anodes experience substantial capacity loss over time due to volume expansion and contraction during lithiation and delithiation, which damages the anode material and restricts cycle life [4,5].

Electrochemical prelithiation can help compensate for initial capacity loss associated with SEI (solid electrolyte interphase) formation and mitigate the detrimental effects of volume expansion to enhance LIB capacity and retention. By utilizing economically feasible materials, such as ester-based solvent and lithium halide salt, the anode can be prelithiated before assembling into a full cell with LFP, effectively increasing the overall available capacity and cyclability [6,7].

The influence of prelithiation is analyzed by using electrochemical data (Q-V curves, rate capability, differential capacity analysis (DCA), and electrochemical impedance spectroscopy (EIS) tests). Prelithiation significantly improves the energy density and cycle life of full cells (prelithiated Si|LFP). We expect to push the limit of energy density, cycle stability, and safety forward, making it suitable for applications in electric vehicles and grid storage.

References
[1] Z. Ashan et al., J. Electrochem. En. Conv. Stor., 18, 010801-1–010801-18 (2021)
[2] L. Yuan et al., Energy Environ. Sci., 4, 269–284 (2011)
[3] S. El Moutchou et al., Mater. Today, 51, A1–A7, (2022)
[4] B. F. Song et al., J. Energy Storage, 28, 101268 (2020).
[5] B. Stumper et al., J. Electrochem. Soc., 170, 060518 (2023).
[6] H.J. Kim et al., Nano Letters, 16, 282–288 (2016)
[7] F. Holtstiege et al., Batteries, 4, 1–39 (2018)