Polymeric Binder Design for Sustainable Lithium-Ion Battery Chemistry

Abstract

The design of binders plays a pivotal role in achieving enduring high power in lithium-ion batteries (LIBs) and extending their overall lifespan. This review underscores the indispensable characteristics that a binder must possess when utilized in LIBs, considering factors such as electrochemical, thermal, and dispersion stability, compatibility with electrolytes, solubility in solvents, mechanical properties, and conductivity. In the case of anode materials, binders with robust mechanical properties and elasticity are imperative to uphold electrode integrity, particularly in materials subjected to substantial volume changes. For cathode materials, the selection of a binder hinges on the crystal structure of the cathode material. Other vital considerations in binder design encompass cost effectiveness, adhesion, processability, and environmental friendliness. Incorporating low-cost, eco-friendly, and biodegradable polymers can significantly contribute to sustainable battery development. This review serves as an invaluable resource for comprehending the prerequisites of binder design in high-performance LIBs and offers insights into binder selection for diverse electrode materials. The findings and principles articulated in this review can be extrapolated to other advanced battery systems, charting a course for developing next-generation batteries characterized by enhanced performance and sustainability.

Keywords: Li-ion battery; anodes; biopolymer; cathodes; polymer binders; ultra-thick electrode; water-soluble binder.

Figure 1

Schematic of binder design considerations in LIB.

Figure 2

(a) Schematic of the synthesis of PAA cross-linked with hydroxypropylpolyrotaxanes (PAA-B-HPR). (b) Cycling performance of Si anodes at 1.4 A g⁻¹ under 55 °C. Reprinted with permission from [23], 2021, American Chemical Society. (c) Thermal expansion rate curves for PAA, PVdF, and CMC binders at a temperature range of 20 to 75 °C. (d) Discharge cycle performances of LMO cathodes with four different binder systems at a rate of 1 C between 3 and 4.3 V at 25 °C. Reprinted with permission from [24], 2014, Elsevier B.V.

Figure 3

(a) Schematics for the binding capability/mechanism of PEO and CRP (carboxyl-rich polymer) binders. Reprinted with permission from [30], 2020, Wiley-VCH GmbH. (b) Dispersion mechanisms of LiFePO₄ in an aqueous suspension in the presence of SBR and sodium carboxymethyl cellulose added via the sequences of (i) sequenced adding and (ii) the simultaneous adding process. Reprinted with permission from [37], 2012, Elsevier B.V.

Figure 4

Molecular structures of natural polymers and monomers: (a) poly-y-glutamic acid; (b) amylopectin; (c) constituent monomers of gum arabic: d-galactose, L-rhamnose, L-arabinose, and D-glucuronic acid; (d) guar gum; and (e) glucomannan. HAXPES results for (f) Si 1 s, (g) C 1 s, and (h) O 1 s core-level spectra for Si/G composite electrodes with PVdF and Li-PGlu binders. Reprinted with permission from [100], 2017, American Chemical Society.

Figure 5

(a) Structure of urushiol and its UV curing mechanism. (b) FT-IR spectra for the expanded Si-O region (800–1300 cm⁻¹) of urushiol monomers. (c,d) XPS Si 2p and C 1 s spectra for the Si/G powders and the powders scraped from the electrode with the Ur Binder. Reprinted with permission from [74], 2018, Elsevier.

Figure 6

Schematics of characteristic binder/carbon distributions in (a) dry-coating electrodes and (b) wet-coating electrodes. SEM images showing representative LiCoO₂ particles in cross-sectioned (c) dry-coating electrodes and (d) wet-coating electrodes. Reprinted with permission from [182], 2016, Springer Nature Limited.