A review of improvements on electric vehicle battery

Abstract

The development of efficient and high-performance electric vehicle (EV) batteries relies on improving various components, such as the anode and cathode electrodes, separators, and electrolytes. This review paper offers an elaborate overview of different materials for these components, emphasizing their respective contributions to the improvement of EV battery performance. Carbon-based materials, metal composites, and polymer nanocomposites are explored for the anode, offering high energy density and capacity. However, they are noted to be susceptible to Li plating. Unique structures, such as Titanium niobium oxide (TiNb₂O₇), offer high theoretical capacity, quick Li⁺ intercalation, and an extended lifecycle. Meanwhile, molybdenum disulfide (MoS₂), with 2D and 3D structures, exhibits high reversible specific capacity, outstanding rate performance, and cyclic stability, showing promising properties as anode material. For cathodes, lithium-iron phosphate (LFP), lithium-cobalt oxide (LCO), lithium-nickel-cobalt-aluminum oxide (NCA), lithium-nickel-manganese-cobalt oxide (NMC), and cobalt-free lithium-nickel-manganese oxide (NMO) are considered, offering specific energy and capacity advantages. For instance, LFP cathode electrodes show good thermal stability, good electrochemical performance, and long lifespan, while NMC exhibits high specific energy, relatively high capacity, and cost savings. NCA has a high specific energy, decent specific power, large capacity, and a long lifecycle. NMO shows excellent rate capability, cyclic stability, and cost-effectiveness but with limited cycle performance. Separator innovations, including polyolefin materials, nanofiber separators, graphene-based composites, and ceramic-polymer composites, are analyzed for use as separators, considering mechanical strength, porosity, wettability with the electrolyte, electrolytic absorption, cycling efficiency, and ionic conductivity. The electrolyte comprises lithium salts such as lithium tetrafluoroborate (LiBF₄), lithium hexafluorophosphate (LiPF₆), and other salts dissolved in carbonate solvents. This improves energy density, capacity, and cycling stability and provides high ion mobility and resistance to decomposition. By examining the existing literature, this review also explores research on the solid electrolyte interface (SEI) and lithium plating, providing valuable insights into understanding and mitigating these critical issues. Despite the progress, limitations such as practical implementation challenges, potential cost implications, and the need for further research on scale-up feasibility and long-term durability are acknowledged. These efforts to enhance the electrochemical characteristics of key battery parameters-positive and negative electrodes, separators, and electrolytes-aim to improve capacity, specific energy density, and overall energy density. These continuous endeavours strive for faster charging of EV batteries and longer travel ranges, contributing to the ongoing evolution of EV energy storage systems. Thus, this review paper not only explores remarkable strides in EV battery technology but also underscores the imperative of addressing challenges and propelling future research for sustainable and high-performance electric vehicle energy storage systems.

Keywords: Battery management systems; Fast-charging lithium-ion batteries; Lithium plating; Solid electrolyte interphase; Thermal management.

Fig. 1

Global EV sales growth for Battery Electric Vehicles (BEVs) and Plug-in Hybrid Electric Vehicles (PHEVs) from 2014 to 2023. Adapted from Irle, 2024 [27].

Fig. 2

Expected and Forecasted growth in global EV sales for battery electric vehicles through to the year 2035 [31].

Fig. 3

Schematic of a typical lithium-ion battery cell [18].

Fig. 4

Schematic of the lithium plating formation process (discussed in later stages) as well as initial SEI Formation Mechanism and Composition (A) Initial reduction reactions of ethylene carbonate (EC) on the graphite electrode interface [83], (B) Illustration of the initial SEI formed on graphite surface during the first cycle of a Li-ion battery [84].

Fig. 5

The illustration of the lithium plating formation process.