Mitigating Voltage Decay and Enhancing Structural Stability of Li-Rich Cathodes via a Robust Polysaccharide Binding Network

Abstract

Li-rich layered manganese-based oxides (LRMOs) are promising high-capacity cathodes for next-generation lithium-ion batteries (LIBs). The challenges for commercialization are mainly rapid capacity fading and discharge voltage decay due to structural transformations, electrolyte decomposition, and transition-metal dissolution. Herein, we construct a robust multifunctional binding network to address these issues by combining two water-based polysaccharide binders, including guar gum (GG) and xanthan gum (XG). The XG-GG composite binder could build a robust hydrogen-bonded network to accommodate LRMO active materials, providing superior mechanical strength and adhesion, which is significantly superior to conventional poly(vinylidene difluoride) (PVDF). The binding network could prevent electrode cracking and active material loss during cycling. In particular, the polar functional groups in the binders could interact with the cathode surface and create a uniform protective cathode electrolyte interphase (CEI) and simultaneously adsorb dissolved transition-metal (TM) ions, suppressing their migration. LRMOs with the XG-GG binder exhibit significantly enhanced electrochemical performance, yielding a high initial capacity of 266.3 mAh/g, improved capacity retention (84.2% after 100 cycles at 1C), and suppressed average voltage decay. A full-cell configuration pairing an XG-GG-based Li-rich cathode with a graphite anode further demonstrates superior long-term stability. Our findings highlight that the establishment of a robust and functional binding network can synergistically overcome the mechanical and interfacial challenges of the high-energy LRMO cathodes and offer a sustainable, water-processable strategy for LIBs manufacturing.