Tailored PVDF Graft Copolymers via ATRP as High-Performance NCM811 Cathode Binders

Tong Liu; Rohan Parekh; Piotr Mocny; Brian P Bloom; Yuqi Zhao; So Young An; Bonian Pan; Rongguan Yin; David H Waldeck; Jay F Whitacre; Krzysztof Matyjaszewski

doi:10.1021/acsmaterialslett.3c00485

Tailored PVDF Graft Copolymers via ATRP as High-Performance NCM811 Cathode Binders

ACS Mater Lett. 2023 Aug 25;5(10):2594-2603. doi: 10.1021/acsmaterialslett.3c00485. eCollection 2023 Oct 2.

Authors

Tong Liu¹, Rohan Parekh^{1

2}, Piotr Mocny¹, Brian P Bloom³, Yuqi Zhao², So Young An¹, Bonian Pan², Rongguan Yin¹, David H Waldeck³, Jay F Whitacre^{2

4}, Krzysztof Matyjaszewski¹

Affiliations

¹ Department of Chemistry, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, Pennsylvania 15213, United States.
² Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213, United States.
³ Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States.
⁴ Scott Institute for Energy Innovation, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213, United States.

Abstract

High-nickel layered oxides, e.g., LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811), are promising candidates for cathode materials in high-energy-density lithium-ion batteries (LIBs). Complementing the notable developments of modification of active materials, this study focused on the polymer binder materials, and a new synthetic route was developed to engineer PVDF binders by covalently grafting copolymers from poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) with multiple functionalities using atom transfer radical polymerization (ATRP). The grafted random copolymer binder provided excellent flexibility (319% elongation), adhesion strength (50 times higher than PVDF), transition metal chelation capability, and efficient ionic conductivity pathways. The NCM811 half-cells using the designed binders exhibited a remarkable rate capability of 143.4 mA h g^-1 at 4C and cycling stability with 70.1% capacity retention after 230 cycles at 0.5 C, which is much higher than the 52.3% capacity retention of nonmodified PVDF. The well-retained structure of NCM811 with the designed binder was systematically studied and confirmed by post-mortem analysis.