Lithium-ion batteries are a leading technology in energy storage, yet lithium’s limited availability poses challenges. As the demand for energy-storage systems increases, there is a push towards finding affordable and readily available materials for rechargeable batteries. Sodium-ion batteries (SIBs) have emerged as a promising alternative, drawing on the abundant sodium resources found in seawater and salt deposits.
Much research has been conducted for improving materials for positive electrodes (cathodes), negative electrodes (anodes), and electrolytes for improving long-cycle stability and achieving a thin solid electrolyte interface (SEI) for SIBs. An SEI is a passive layer formed on the anode surface during the initial charge/discharge cycles, which prevents the anode from degrading due to reactions with the electrolyte.
A well-formed SEI is crucial for battery performance. In this context, hard carbon (HC) has emerged as a promising anode material. Still, its commercialization has been difficult as it forms an uneven, thick, and weak SEI due to increased electrolyte consumption, which lowers charging/discharging stability and reaction speeds. To address these issues, binders such as carboxymethyl cellulose salts, poly(acrylic acid) derivatives, and poly(vinylidene fluoride) (PVDF) have been used. However, these binders cause slow diffusion of Na ions in the anode, leading to poor rate capability of HC-based SIBs.
To overcome these shortcomings, Professor Noriyoshi Matsumi and Doctoral Course Student Amarshi Patra from the Japan Advanced Institute of Science and Technology (JAIST) developed an HC anode using a poly(fumaric acid) (PFA) binder. Their findings were published in the Journal of Materials Chemistry A on May 10, 2024.
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