Enabling Aqueous Processing of Ni‐Rich Layered Oxide Cathodes via Systematic Modification of Biopolymer (Polysaccharide)‐Based Binders

• Published in: Advanced energy and sustainability research Vol. 5; no. 9
• Main Authors: Albers, Simon, Timmermann, Jens, Brake, Tobias, Arifiadi, Anindityo, Gerlitz, Anna I., Börner, Markus, Winter, Martin, Kasnatscheew, Johannes
• Format: Journal Article
• Language: English
• Published: Wiley-VCH 01.09.2024
• Subjects: aqueous processing; binder modifications; biopolymers; electrode binders; electrode paste viscosity; Ni‐rich layered oxides
• ISSN: 2699-9412; 2699-9412
• DOI: 10.1002/aesr.202400117

Aqueous processing of lithium (ion) battery cathodes based on Ni‐rich layered oxides like LiNi0.83Co0.12Mn0.05O2 (NCM) can reduce costs, increase sustainability, and pave the way for F‐free, e.g., biopolymeric binders, however, the degradation of water‐sensitive Ni‐rich NCM remains a challenge. Besides strategies like NCM coatings and processing additives, customized binders can be performance‐decisive via impacting both, electrode processing aspects (paste viscosity, particle dispersibility, etc.) and chemical interactions with NCM surface, though, a distinction between these two impacting factors is difficult given their mutual influences. For this reason, a bifunctional binder system is chosen in this work, i.e., highly viscous xanthan and low viscous pullulan, both polysaccharides known from the food industry, which realize constant viscosity and processing, finally enabling systematic investigation of binder modifications (here pullulan) with various side groups. In fact, while the rate performance remains constant, suggesting a similar composite network with comparable electronic and ionic conductivities, the modified binders affect the NCM||graphite cycle life, where a higher substitution degree of carboxymethylated pullulan can even compete with N‐methyl‐2‐pyrrolidone/polyvinylidene difluoride state‐of‐the‐art system at conventional upper charge voltage (4.2 V); while at 4.5 V water‐reasoned NCM damages get obvious, as seen by enhanced electrode cross‐talk via transition metal deposition on anode. Herein, the influence of polysaccharide‐based binders for aqueous processed Ni‐rich cathodes on charge/discharge cycle performance is systematically investigated. For a similar composite network, the viscosity of the electrode paste is kept constant via the dual binder approach with high and low viscous xanthan and pullulan. The modifications of the latter can even compete with state‐of‐the‐art processing routes.