A Comprehensive Study of Hydrolyzed Polyacrylamide as a Binder for Silicon Anodes
Andrea Miranda1, Xiaoyi Li2, Atetegeb Meazah Haregewoin3
1Department of Chemistry , Rice University , 6100 Main Street, MS-60 , Houston , Texas 77005 , United States.
ACS Applied Materials & Interfaces
|October 26, 2019
Summary
Partially hydrolyzed polyacrylamide (HPAM) shows promise as a binder for silicon anodes in lithium-ion batteries. Moderate molecular weight HPAM offers optimal performance, balancing mechanical strength and electrode uniformity for improved stability and capacity.
Area of Science:
- Materials Science
- Electrochemistry
- Polymer Science
Background:
- Silicon anodes offer high theoretical capacity for lithium storage but suffer from poor long-term stability in current composite electrode formulations.
- Polymeric binders significantly influence the stability and capacity of silicon anodes, yet a comprehensive understanding of how their physicochemical properties affect performance is lacking.
- Key properties influencing binder performance include adhesion, mechanical integrity, and ion diffusion, which are critical for electrochemical stability.
Purpose of the Study:
- To comprehensively investigate the physical properties and electrochemical performance of a molecular-weight series of partially hydrolyzed polyacrylamide (HPAM) in silicon anodes.
- To correlate the physicochemical properties of HPAM binders with the electrochemical stability and performance of silicon anodes.
- To identify optimal HPAM characteristics for enhanced silicon anode performance in energy storage applications.
Main Methods:
- Synthesized and characterized a series of partially hydrolyzed polyacrylamide (HPAM) with varying molecular weights (3-20 × 10^6 g/mol).
- Quantified mechanical strength, electrolyte uptake, and adhesion of HPAM films to silicon, copper, and carbon substrates.
- Evaluated the electrochemical performance and stability of silicon anodes utilizing HPAM binders through cycling tests.
Main Results:
- HPAM binders exhibited favorable properties, including good adhesion, high mechanical strength, and electrochemical stability, with no observed electrolyte uptake across all molecular weights.
- Mid- and high-molecular-weight HPAM thin films effectively suppressed silicon lithiation.
- Composite electrodes demonstrated high initial capacities (>3000 mAh/g) and retained significant capacity after 100 cycles (1639 mAh/g), with moderate molecular weight HPAM showing the best performance due to an optimal balance of mechanical strength and electrode uniformity.
Conclusions:
- Partially hydrolyzed polyacrylamide (HPAM) is a promising, low-cost binder for silicon anodes, offering improved electrochemical stability and capacity.
- Binder performance is influenced by a trade-off between mechanical strength and electrode uniformity, with moderate molecular weight HPAM achieving the best results.
- Further research into binder properties can optimize silicon anode design for next-generation energy storage.
