Effect of Electrolyte Concentration on the Performance of Batteries

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1 Salem State University Digital Commons at Salem State University Honors Theses Student Scholarship Effect of Electrolyte Concentration on the Performance of Batteries Krystal G. Gmyrek Follow this and additional works at: Part of the Materials Chemistry Commons, and the Other Chemistry Commons Recommended Citation Gmyrek, Krystal G., "Effect of Electrolyte Concentration on the Performance of Batteries" (2014). Honors Theses. Paper 26. This Thesis is brought to you for free and open access by the Student Scholarship at Digital Commons at Salem State University. It has been accepted for inclusion in Honors Theses by an authorized administrator of Digital Commons at Salem State University.

2 EFFECT OF ELECTROLYTE CONCENTRATION ON THE PERFORMANCE OF BATTERIES Honors Thesis Presented in Partial Fulfillment of the Requirements For the Degree of Bachelor of Science in Chemistry In the College of Arts and Sciences at Salem State University By Krystal Gmyrek Dr. Jayashree Ranga Faculty Advisor Department of Chemistry and Physics *** Commonwealth Honors Program Salem State University 2014

3 Abstract This project is geared towards the design of a greener battery. The current battery design consists of Copper and Zinc electrodes with an electrolyte composition of Copper Sulfate (CuSO 4 ), Zinc Nitrate (Zn(NO 3 ) 2 ), and Potassium Chloride (KCl). The performance of the battery with Copper Sulfate and Potassium Chloride was comparable to the performance of the battery with Zinc Nitrate, Copper Sulfate, and Potassium Chloride. Next we attempted to replace Potassium Chloride with a greener solute Sodium Chloride (NaCl), common table salt. We optimized the concentration of NaCl in our batteries. Batteries with optimized concentration of NaCl resulted in significantly higher power density. Our final product a greener battery, now consists of Zinc and Copper rods with Copper Sulfate and Sodium Chloride as the electrolyte.

4 Background The search for greener alternatives for energy is an on-going process and this project is presented as a possible means for greener battery design. This experiment had been traditionally done with copper sulfate and zinc nitrate. Batteries have a cathode and an anode. The Anode is negatively charged where oxidation leads to the generation of electrons: Zn(s)è Zn 2+ (aq) + 2e - Cathode is positively charged where reduction leads to consumption of electrons: Cu 2+ (aq) + 2e - è Cu(s) The overall chemical reaction inside the battery could be represented as: Zn(s)+Cu 2+ (aq) è Zn 2+ (aq) + Cu(s) Copper Sulfate, Zinc Nitrate, Potassium Chloride, and Sodium Chloride are the electrolytes used in the battery design. Electrons flow through the external circuit. In this study we investigated the following effects: a) Presence and absence of Zinc Nitrate b) Effect of Potassium Chloride vs. Common Salt c) Study the performance of a greener battery Using only copper sulfate the same current can be obtained which eliminates the additional and redundant chemical Zinc NItrate. Addition of Potassium Chloride assists in ion transport, hence the current in the system increases. Procedure These chemicals were acquired by Salem State University from Sigma-Aldrich without any further purification.

5 This home built battery uses a Zinc rod for the anode and a Copper rod for the cathode. These rods were inserted into a container at a fixed distance. Two Multimeters were then attached to the rods in order to record current and voltage for 30 minutes. The electrolyte effect of Zinc Nitrate was studied using the following solutions: (a) 0.1M CuSO4, (b) 0.1M CuSO M Zn(NO3)2, (c) 0.1M CuSO M Zn(NO3) M KCl, (d) 0.1M CuSO M KCl. It was determined through this experimentation that Zinc Nitrate was redundant. With the elimination of Zinc Nitrate we then tested different concentrations of Sodium Chloride in place of Potassium Chloride. Various concentrations of NaCl were studied in order to optimize the concentration of NaCl with the following solutions: (a) 0.1M CuSO M KCl, (b) 0.1M CuSO M NaCl, (c) 0.1M CuSO M NaCl, (d) 0.1M CuSO M NaCl. Each solution was run three times and the average power density was calculated.

6 Results and Discussion Zinc Nitrate had no effect when paired with Potassium Chloride. Hence, Zinc Nitrate was eliminated from the set up. Common Salt (Sodium Chloride) was considered to replace Potassium Chloride. To optimize the concentration of Sodium Chloride: 0.1M, 0.5M, and 1.0M NaCl were used. It was found that 1.0M NaCl was the optimal concentration of Sodium Chloride in the battery system. We have successfully created a greener battery. We replaced Potassium Chloride with common table salt (Sodium Chloride). Optimized concentrations of Sodium Chloride resulted in significantly higher power density than Potassium Chloride. Our final greener battery uses Copper Sulfate with Common Salt as electrolyte.

7 References 1. "ChemExper - Catalog of Chemicals Suppliers, Physical Characteristics and Search Engine." ChemExper - Catalog of Chemicals Suppliers, Physical Characteristics and Search Engine. N.p., n.d. Web. 08 Oct < 2. Cheng, Jie, Yue-Hua Wen, Gao-Ping Cao, and Yu-Sheng Yang. "Influence of Zinc Ions in Electrolytes on the Stability of Nickel Oxide Electrodes for Single Flow Zinc nickel Batteries." Journal of Power Sources (2011): Print. 3. Mills, Allan A. "Early Voltaic Batteries: An Evaluation in Modern Units and Application to the Work of Davy and Faraday." Annals of Science 60.4 (2003): Print.

8 Appendix I Effect of Electrolyte Zinc Nitrate: Effect of elimination of Zinc Nitrate on the performance of batteries Effect of Electrolyte Potassium Chloride vs Common Salt: Effect of replacing KCl with greener table salt, NaCl, on the performance of batteries.

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10 Appendix II Potassium Chloride MF: KCl MW: BP: 1420 C MP: 770 C Sodium Chloride MF: NaCl MW: BP: ( C): 1461 MP: ( C): 801 Copper Sulfate MF: CuSO 4 MW: MP: 200 C Hazard: XN: Harmful N: Dangerous for the environment Risk: 22: Harmful if swallowed. 36/38: Irritating to eyes and skin. 50/53: Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. Safety: 22: Do not breathe dust. 60: This material and its container must be disposed of as hazardous waste. 61: Avoid release to the environment. Refer to special instructions / safety data sheets.

11 Zinc Nitrate MF: Zn(NO 3 ) 2 MW: Hazard O: Oxidizing XN: Harmful N: Dangerous for the environment Risk 8: Contact with combustible material may cause fire. 22: Harmful if swallowed. 36/37/38: Irritating to eyes, respiratory system and skin. 51/53: Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.