Lean electrolytes enhancing intrinsic safety of energy-dense nickel-rich lithium-ion batteries

The energy-dense lithium-ion batteries (LIBs) with ultrahigh-nickel cathodes and silicon-based anode are confronted with critical safety issues, hindering their widespread application. The electrolyte loading plays a crucial role in governing both thermochemical reactions and interfacial stability within LIBs. Herein, a lean-electrolyte strategy of 1.8 g·Ah −1 is implemented in 1.1 Ah LiNi 0.91 Co 0.07 Mn 0.02 O 2 |graphite@silicon dioxide (NCM91|Gr@SiO) pouch cells, enhancing the intrinsic safety of energy-dense LIBs. Specifically, by reducing electrolyte loading from 4.5 g·Ah −1 to 1.5 g·Ah −1 , the heat generated by the anode-electrolyte reaction decreases significantly by 39.0 %, from 3959 mJ to 2415 mJ. Similarly, the cathode-electrolyte reaction exhibits a 27.7 % reduction in heat release, declining from 844 mJ to 610 mJ. Hot-box tests indicate that a 1.8 g·Ah −1 based cell can reduce the maximum temperature by 181.2 °C during thermal runaway and generate only sparks rather than intense combustion, thereby mitigating fire and explosion hazards. Furthermore, the 1.8 g·Ah −1 loading is identified a balance between thermal safety and electrochemical stability, demonstrating an excellent capacity retention of 88.5 % after 300 cycles (compared to a capacity plummet at 1.5 g·Ah −1 , and 89.1 % at 4.5 g·Ah −1 ). This study offers practical insights for developing energy-dense LIBs under lean-electrolyte conditions, reducing overall costs while maximizing high-capacity material utilization. • The lean electrolyte strategy effectively boosts intrinsic safety in high-energy-density NCM91|Gr@SiO lithium-ion cells. • Under thermal abuse, lean electrolyte loading suppresses side reactions and lowers heat generation. • Lean electrolyte strategy reduces thermal runaway severity and minimizes flame risk in pouch cells. • The electrolyte loading of 1.8 g·Ah −1 balances thermal safety and cycling durability (88.5 % retention after 300 cycles).