Effect of oxalic acid concentration on the adhesion and surface properties of silicon anodes for battery applications

Date of Publication

8-14-2026

Document Type

Master's Thesis

Degree Name

Master of Science in Applied Physics

Subject Categories

Physics

College

College of Science

Department/Unit

Physics

Thesis Advisor

Maria Carla F. Manzano

Defense Panel Chair

Gil Nonato C. Santos

Defense Panel Member

Emmanuel T. Rodulfo
Michelle Marie Villamayor (External)

Abstract (English)

Silicon has attracted considerable attention as a potential anode material for battery applications because of its exceptionally high theoretical specific capacity (~4,200 mAh/g). However, its practical application can be limited by poor interfacial adhesion between the silicon electrode coating and the copper current collector, which may contribute to electrode delamination and degradation. This study investigated the effect of oxalic acid (OA) concentration on the adhesion and surface properties of silicon-based electrodes. Silicon-based electrodes consisting of silicon powder, Super P carbon black, and a guar gum binder were fabricated by slurry casting onto copper-foil current collectors. Oxalic acid was incorporated into the slurry at concentrations of 0.00, 0.05, 0.10, and 0.20 wt%. Water contact angle (WCA) measurements demonstrated that increasing OA concentration progressively improved surface wettability. Meanwhile, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) revealed that moderate OA addition, particularly at 0.05 wt%, was associated with a more uniform coating morphology, a more homogeneous distribution of silicon, and reduced exposure of the copper substrate. Peel testing showed that the 0.05 wt% OA electrode exhibited the highest reliable peeling force, whereas excessive OA addition at 0.20 wt% resulted in greater coating delamination and reduced adhesion. FTIR analysis indicated that both adhesive tapes exhibited rubber-based adhesive characteristics, while 3M 3039 showed additional ester- and ether-related functional groups and greater hydrophobicity than 3M 681. The 3M 3039 tape exhibited internal adhesive failure. It was therefore not considered a reliable measure of electrode adhesion, whereas 3M 681 produced failure behavior relevant to electrode adhesion and was more suitable for evaluating the electrode–current collector interface. Cyclic voltammetry showed generally similar responses across the electrode formulations, with no distinct Faradaic redox peaks. Among the concentrations investigated, the 0.05 wt% OA electrode exhibited the most 7consistent response over 10 cycles, providing supporting evidence of favorable short-term cycle-to-cycle reproducibility. Overall, the results demonstrate that 0.05 wt% OA was the best-performing concentration among those investigated, providing a favorable balance of surface wettability, interfacial adhesion, and coating uniformity. The findings highlight the potential of controlling oxalic acid concentration as an interfacial modification strategy to improve the mechanical reliability and surface characteristics of silicon-based electrodes for battery applications.

Abstract Format

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Abstract (Filipino)

Ang silikon ay nakakuha ng malaking atensyon bilang potensyal na materyal para sa anode sa mga aplikasyon ng baterya dahil sa pambihira nitong mataas na teoretikal na tiyak na kapasidad na humigit-kumulang 4,200 mAh/g. Gayunpaman, maaaring malimitahan ang praktikal na paggamit nito dahil sa mahinang interfacial adhesion sa pagitan ng silicon electrode coating at ng copper current collector, na maaaring magdulot ng delamination at pagkasira ng electrode. Sinuri sa pag-aaral na ito ang epekto ng konsentrasyon ng oxalic acid (OA) sa adhesion at mga katangian ng ibabaw ng mga electrode na nakabatay sa silikon. Ang mga silicon-based electrode na binubuo ng silicon powder, Super P carbon black, at guar gum binder ay ginawa sa pamamagitan ng slurry casting sa mga copper-foil current collector. Isinama ang oxalic acid sa slurry sa mga konsentrasyong 0.00, 0.05, 0.10, at 0.20 wt%.

Ipinakita ng mga pagsukat ng water contact angle (WCA) na ang pagtaas ng konsentrasyon ng OA ay unti-unting nagpahusay sa surface wettability. Samantala, ipinakita ng scanning electron microscopy (SEM) at energy-dispersive X-ray spectroscopy (EDS) na ang katamtamang pagdaragdag ng OA, partikular sa 0.05 wt%, ay nauugnay sa mas pantay na morphology ng coating, mas homogenous na distribusyon ng silikon, at mas kaunting pagkakalantad ng copper substrate. Ipinakita ng peel testing na ang electrode na may 0.05 wt% OA ay nagkaroon ng pinakamataas na maaasahang peeling force, samantalang ang labis na pagdaragdag ng OA sa 0.20 wt% ay nagresulta sa mas malaking delamination ng coating at nabawasang adhesion.

Ipinahiwatig ng FTIR analysis na ang parehong adhesive tape ay may katangiang rubber-based adhesive, habang ang 3M 3039 ay nagpakita ng karagdagang mga functional group na nauugnay sa ester at ether at mas mataas na hydrophobicity kumpara sa 3M 681. Ang 3M 3039 tape ay nagpakita ng internal adhesive failure. Dahil dito, hindi ito itinuring na maaasahang panukat ng electrode adhesion, samantalang ang 3M 681 ay nagpakita ng failure behavior na may kaugnayan sa electrode adhesion at mas angkop para sa pagsusuri ng interface sa pagitan ng electrode at current collector.

Ipinakita ng cyclic voltammetry na sa pangkalahatan ay magkakatulad ang mga tugon ng iba't ibang formulation ng electrode, nang walang malinaw na Faradaic redox peaks. Sa mga konsentrasyong sinuri, ang electrode na may 0.05 wt% OA ay nagpakita ng pinakapare-parehong tugon sa loob ng 10 cycles, na nagbibigay ng suportang ebidensya ng paborableng short-term cycle-to-cycle reproducibility.

Sa kabuuan, ipinapakita ng mga resulta na ang 0.05 wt% OA ang pinakamahusay na gumaganang konsentrasyon sa mga konsentrasyong sinuri, dahil nagbibigay ito ng paborableng balanse ng surface wettability, interfacial adhesion, at coating uniformity. Binibigyang-diin ng mga natuklasan ang potensyal ng pagkontrol sa konsentrasyon ng oxalic acid bilang isang interfacial modification strategy upang mapahusay ang mechanical reliability at mga katangian ng ibabaw ng mga silicon-based electrode para sa mga aplikasyon ng baterya.

Abstract Format

html

Language

English

Format

Electronic

Keywords

Silicon; Oxalic acid; Surface chemistry; Electrodes

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Embargo Period

8-26-2026

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