Smart symbiotic lithium-sulfur batteries under extremely low-temperature conditions

Lithium-sulfur batteries (LSBs) fail catastrophically under ultralow temperature due to frozen polysulfide conversion kinetics, with no existing technology achieving high-energy-density operation below -40°C. Here, we report a self-regulating LSB system, the 'smart symbiosis' cell, that activates multifield synergy at interface reaction sites to overcome kinetic barriers under low temperature. This directly modulates the transport of ions/electrons and the spin electron states of reaction sites at the quantum level, enabling wave-shaped charge/discharge profiles and achieving a ratio of 3.11 between the first plateau and the second plateau (theoretical value 3.0). The ultratheoretical capacity mechanism is revealed-magnetic field-induced enhancement of kinetics and interfacial reactions. The pouch cell achieves an energy density of 454.5 Wh kg^-1 (based on total system mass) and 219.1 Wh kg^-1 (with device consumption) at -80°C. This technology could increase the capacity of batteries by 9.5 times at low temperatures with an energy consumption of ∼0.091% °C^-1 of the battery energy, while the conversion retention rate remains as high as 87% after 200 cycles (∼2800 h), and breaks the lowest temperature record. This new battery system opens the door to extremely wide temperature applications for LSBs and could be extended to other batteries.