Evaluating carbon efficiency across the lithium-ion battery industry using a SMOTE-augmented Super-SBM approach

The lithium-ion battery (LIB) industry, a cornerstone of energy storage technology, is critical in the global transition towards low-carbon energy systems. However, its carbon emission performance remains poorly understood. This study developed a hybrid slacks-based measure-synthetic minority over-sampling technique model to systematically evaluate the carbon emission efficiency and spatial distribution of 70 Chinese LIB enterprises in 2024, indicating potential transfer and structural disparities of emissions between the supply and consumption segments. Results showed enterprises in the supply segment as the primary emission sources, with total emissions reaching 4.32×10⁶ t CO₂-eq and exhibiting a "low-income, high-emission" pattern, where anode material producers contributed most. Contrastingly, enterprises in the consumption segment exhibited lower emissions (9×10⁴ t CO₂-eq) and higher efficiency, characterized as "high-revenue, low-emission," with LIB manufacturers being the lowest emitters. Carbon emission efficiency varied markedly across the chain, with the highest and lowest efficiency scores being 1.79 and 0.08, respectively. The supply segment displayed pronounced internal heterogeneity and wide dispersion, while efficiency within the consumption segment was relatively concentrated, with LIB manufacturers showing a bimodal distribution. Spatially, corporate carbon efficiency exhibited a "multi-center and plate-like" pattern, closely related to regional economic development and industrial specialization. These findings provide empirical insights for holistic carbon management, efficiency improvement, and differentiated emission reduction strategies formulation in the LIB industry.