14500 battery

Flexible sulfur carrier for high-performance 14500 battery

In recent years, with the promotion and application of portable electronic equipment and electric vehicles, today's society has put forward new challenges to electrochemical energy storage devices. Traditional lithium-ion batteries are limited by the low theoretical capacity of electrode materials and are difficult to meet the requirements of high energy density energy storage systems. Lithium-sulfur batteries based on multi-electron conversion reactions are considered to be one of the most promising next-generation high-energy battery systems due to their ultra-high specific energy, abundant raw material sources, low prices, low toxicity and harmlessness, and have become an important research direction and hot spot in the current electrochemical energy storage field.

However, the inherent defects of lithium-sulfur batteries hinder their large-scale use. On the one hand, due to the low conductivity of sulfur and its reduced product polysulfide compounds (Li2S/Li2S2), the utilization rate of active materials in lithium-sulfur batteries is low and the rate performance is poor; on the other hand, the soluble polysulfide compounds produced during the charge and discharge process will lead to the emergence of the "shuttle effect". Therefore, the development of positive electrode materials with high conductivity and strong adsorption capacity for polysulfide compounds is the key to obtaining high-performance lithium-sulfur batteries.

In response to the above problems, the Advanced Energy Storage Materials and Technology Research Group of Qingdao Institute of Bioenergy and Process Technology, Chinese Academy of Sciences, based on the modification of the positive electrode sulfur carrier, prepared a flexible sulfur carrier with a "reinforced concrete-like" structure, which achieved high sulfur loading, high sulfur utilization and long cycle life of lithium-sulfur batteries. With graphene film as the current collector and lignin fiber and carbon nanotubes as composite carriers, the flexible sulfur carrier has excellent conductivity and polysulfide anchoring ability, while combining the depolarization characteristics of graphene. The 14500 battery assembled with this current collector has a battery capacity of up to 1632.5mAhg-1 (97.5% of the theoretical capacity) at 0.1C, and a capacity retention rate of 86.5% after 500 cycles at 1.0C. Even at a high sulfur loading of 9.2mgcm-2, the 14500 battery still exhibits excellent cycle stability, and the capacity retention rate after 100 cycles at 0.5C is 91.5%. This work provides a new idea for improving the sulfur utilization and cycle life of lithium-sulfur batteries.

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