Fuel cell efficiency is theoretically expected to decrease with increasing temperature, but practical observations indicate the opposite due to lower voltage losses at higher temperatures. Higher temperature fuel cells can operate at greater voltages, making them more advantageous despite their lower efficiency. This phenomenon is supported by research from the Department of Aerospace and Mechanical Engineering at the University of Notre Dame. The discussion highlights the need for more sources to understand this counterintuitive behavior fully. Overall, higher operating temperatures can lead to better performance in fuel cells despite theoretical efficiency concerns.