Revenue fell by 29.8 percent to 3.94 trillion won in the July-September quarter.
Although battery supply to its North American partner facilities increased, its flagship battery division saw operating profit plunge 85 percent from a year earlier to 63.5 billion won.
"Despite challenging business conditions, we have laid the groundwork for a mid- to long-term growth, centered on premium prismatic batteries," Samsung SDI CEO Choi Yoon-ho said. "We will seize new opportunities as market demand recovers, backed by our industry-leading technological competitiveness and quality."