Chitosan as Enabling Polymeric Binder Material for Silicon‐Graphite‐Based Anodes in Lithium‐Ion Batteries

• Published in: Energy technology (Weinheim, Germany) Vol. 11; no. 3
• Main Authors: Hamzelui, Niloofar, Linhorst, Max, Martin Nyenhuis, Gabriela, Haneke, Lukas, Eshetu, Gebrekidan Gebresilassie, Placke, Tobias, Winter, Martin, Moerschbacher, Bruno M., Figgemeier, Egbert
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-03-2023
• Subjects: Acetylation; Ammonia; Anodes; Batteries; Binders; Binders (materials); Biopolymers; Bonding strength; Carboxymethyl cellulose; Cellulose; Chitosan; Citric acid; Cobalt; Cobalt oxides; Commercialization; cross-linking; Crosslinking; Degree of polymerization; Electrochemical analysis; Electrochemistry; Electrode materials; Electrodes; Electrolytic cells; Electrons; free-standing electrodes; Functional groups; Graphite; graphite (Gr); Lithium; lithium-ion batteries (LIB); Manganese; Nickel; Photoelectrons; Polyacrylic acid; Silicon; silicon-graphite (Si/Gr); Sodium carboxymethyl cellulose; Solid electrolytes; Surface chemistry
• ISSN: 2194-4288; 2194-4296
• DOI: 10.1002/ente.202201239

Massive volume change during (de‐)lithiation and subsequent challenges, such as pulverization of active materials, delamination of electrode from the current collector, and fragile solid electrolyte interphase, are among the main impediments hindering the large‐scale commercialization of silicon‐containing anode materials in lithium‐ion batteries. In this regard, designer polymeric binders with unique chemistries are considered as enabling solutions. Polymeric materials endowed with functional groups such as –OH, –COOH/COO−, and –NH2/NH3+, capable of building strong H bonds, are hailed as effective binders for Si‐containing anode materials. Herein, chitosan biopolymers are investigated as a green and environmentally friendly binder in a silicon/graphite (Si/Gr) anode and compared to lithium poly(acrylic acid)/sodium carboxymethyl cellulose binders. The effect of degree of acetylation (DA) and degree of polymerization of chitosan on the electrochemical performance of Si/Gr anode‐based cells is investigated. Anodes with chitosan binder with DA of 50% show the most promising electrochemical performance in Si/Gr||lithium metal and lithium nickel manganese cobalt oxide (NMC622)||Si/Gr cells. Crosslinking of chitosan binder with citric acid monohydrate in combination with free‐standing electrodes results in improved electrochemical performance in full cells. The surface chemistry of electrochemically cycled Si/Gr anodes with/without chitosan binder is investigated by X‐ray photoelectron spectroscopy.
Chitosan biopolymers with different degrees of acetylation and degrees of polymerization are investigated as a suitable binder for Si/Gr‐based anodes, leading to enhanced performance of the elect rodes compared to using state‐of‐the‐art lithium poly(acrylic acid)/sodium carboxymethyl cellulose binder. The optimized chitosan binder is further investigated as cross‐linked with citric acid and in a free‐standing electrode.