Binders are electrochemically inactive electrode components. However, their chemical and physical nature greatly affects battery performance and plays a key role in electrode integrity and interface reactivity. The binders thus have a strong impact on battery capacity retention and cycle life. Water-processable binders would make the electrode preparation process cheap and environmentally friendly and provide a viable alternative to polyvinylidene difluoride (PVdF). Here we report the use of sodium alginate (SA) as binder for LiNi 0.5 Mn 1.5 O 4 (LNMO), one of the most promising cathode materials for high-voltage and high-energy LIBs. We demonstrate that electrodes with high mass loading containing SA have excellent specific discharge capacity (120 mAh g −1 at C/3 and 100 mAh g −1 at 5C) with negligible overpotentials in conventional electrolyte based on ethylene carbonate (EC): dimethyl carbonate (DMC) and 1 M LiPF 6 , where the reactivity of LNMO is known to negatively affect stability. The electrodes with SA also show a good stability over subsequent cycles of charge and discharge at 1C with capacity retention of 95% and 86% with respect to the initial cycles at the 100th and 200th cycle. Lithium-ion batteries (LIBs) have been on the market for 25 years and recently are being widely used in electric vehicles.1,2 Research is currently focused on improving the safety and performance of LIBs in terms of gravimetric and volumetric energy and power as well as reducing the costs and toxicity of battery components and of the manufacturing process.3,4 While the three main active battery components, i.e. anode, cathode and electrolyte, are widely studied, as shown by numerous review papers, [5][6][7][8] it is worth noting that such inactive battery components as separators are extremely important in overall operation. 9 The same holds true for the conductive agent (usually carbon black) and the binder that support the electrochemical processes even if present in low weight percentages in electrode composite. The former improves electronic conductivity and, hence, the rate capability of the electrode. The latter acts as glue for active material and the conductive agent and can also improve adhesion with the current collector. Although electrochemically inactive, the chemical and physical nature of polymeric binders can enhance battery performance, control the interface structure of the electrode and has a strong impact on battery capacity retention and cycle life. 10The most widely used binder for LIBs is polyvinylidene difluoride (PVdF). While displaying all the desirable binder properties, such as good adhesion strength to the current collector and good electrochemical stability, it can also soak up a large amount of liquid electrolyte, a property that has its pros and cons.11 A facile penetration of the electrolyte inside the composite electrode results in a high interfacial area of active material in contact with the electrolyte. While this facilitates Li + transport, it also promotes unwanted side-reactions. Furth...

The use of water-processable binders could lower production costs and grant easier and more environment-friendly production of Li-ion batteries. This work investigates the use of two water-processable binders, namely polyvinylacetate (PVA) and sodium alginate (Alg), in high-voltage cathode electrodes for Li-ion batteries. We focused our work on the use of these sustainable binders for cathodes based on LiNi0.5Mn1.5O4, a commercially available material with a very high Li+ deinsertion/insertion potential (4.7-4.75 V versus Li+/Li) and a theoretical specific capacity of 147 mAh g-1. The electrochemical performance of cathodes with PVA and Alg are compared to those obtained with PVdF-based electrodes at 30°C in conventional electrolyte. Among all, Alg-based cathodes show the best rate capability up to 5C and cycle stability, with 95% capacity retention after 100 cycles because of the formation of thinner and less resistive layer on the electrode than PVA- and PVdF-based cathodes.