Towards high-performance lithium-ion batteries by introducing graphene-based materials into LiFePO4 cathodes: A review

In recent years, concerted research efforts have been aimed at improving the electrochemical performance of Li-ion batteries (LIBs) to meet the ever-increasing demand for energy storage devices in various applications, particularly powering of portable electronic devices and electric vehicles. One such novel approach entails the materials engineering of the basic LIB components, especially the cathode, which not only dominates the battery cost, but also limits the energy density. Meanwhile, the cathode is typically made up of LiCoO₂, a layered oxide, which despite having a relatively high energy density (∼150 – 190 Wh kg⁻¹), suffers from limited practical capacity (∼140 mA h g^–1), in addition to the scarcity, toxicity and high-cost of Co. Consequently, LiFePO₄ (LFP), a polyanion oxide, has emerged as a promising alternative owing to its relatively higher practical capacity (∼165 mA h g^–1), coupled with the more abundance, less toxicity and lower cost of Fe than Co. Nevertheless, LFP has shortcomings mainly due to its low ionic and electronic conductivities, which limit the cathode rate capability and energy density (∼90 – 140 Wh kg⁻¹). As a result, highly stable and conductive carbon-based materials, particularly graphene and its derivatives, have recently been introduced to LFP to enhance electron and Li-ion transport, while also prolonging the cycle life. Herein, the research progress made over the last five-year period (2018–2023) to improve the rate performance and cyclability of LFP cathodes by utilizing graphene-based materials is highlighted. Future research directions for employing LFP/graphene-based composite cathodes to further advance the electrochemical performance of next-generation LIBs are also discussed to set the stage for commercial applications.