Grantee Research Project Results

Final Report: Lithium-ion Batteries Based on Aqueous Electrolyte: A New Generation of Sustainable Energy Storage Devices

EPA Contract Number: EPD14009
Title: Lithium-ion Batteries Based on Aqueous Electrolyte: A New Generation of Sustainable Energy Storage Devices
Investigators: M. Hagh, Dr. Nader
Small Business: NEI Corporation
EPA Contact: Richards, April
Phase: I
Project Period: May 1, 2014 through April 30, 2015
Project Amount: $99,992
RFA: Small Business Innovation Research (SBIR) - Phase I (2014) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , Pollution Prevention/Sustainable Development , SBIR - Innovation in Manufacturing

Description:

Commercial Li-ion batteries use organic electrolytes, which are flammable and have been a concern, particularly in large format cells. In addition to safety, disposal and recycling of the toxic organic solvents without impacting the environment are major hurdles facing large sized Li-ion batteries. The Phase I project has demonstrated the use of an aqueous- based electrolyte, which overcomes the safety and environmental concerns posed by organic electrolytes. The goal is to extend the electrochemical stability window of the aqueous electrolyte close to that of the organic-based electrolyte, and thereby enable reversible Li-ion insertion into and extraction from the electrode. This has been accomplished by modifying both the electrode structure and the electrolyte composition.

Summary/Accomplishments (Outputs/Outcomes):

During the Phase I program, it was shown that an electrolyte using 5M lithium nitrite solution has much wider electrochemical stability window relative to binary or even ternary systems. The stability window of LiNO₃ and LiCl-ZnCl₂-LiOH electrolytes were 2.5V and 0.6V, respectively, which is nearly four times that of ternary systems. More than half a dozen cathode and anode materials were synthesized, and powder characteristics and electrochemical performance of the materials were evaluated in organic as well as selected aqueous-based electrolytes. It was shown that structural modifications to the electrodes can further increase the electrochemical stability of the electrolyte to about 2.8-3.0V. This stability window is quite high and approaches that of typical organic-based electrolytes, which is 3.5V. The modified electrodes were tested in five different pairs of battery full cells. It was shown that the modifications led to about 50 percent higher capacity than the pristine cells, with much lower first-cycle irreversible capacity loss.

Conclusions:

The feasibility of an aqueous-based Li-ion battery using a highly stable aqueous electrolyte and modified electrodes was demonstrated in the Phase I program. The structural modifications introduced in the electrodes enhanced the stability window of the aqueous electrolyte, approaching to that of organic electrolytes.

Commercialization: It was demonstrated that the developed aqueous-based Li-ion battery technology presents a new path to enable the use of safe and environmentally friendly electrolytes. Both conventional Li-ion and aqueous-based nonlithium battery manufacturers have expressed interest in working with NEI to further develop the technology.

Supplemental Keywords:

lithium-ion battery, aqueous, electrolyte, electrode, manufacturing

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