The demand for energy increases steadily with time due to population and economic growth and advances in lifestyle. As energy usage increases, concerns about environmental pollution associated with the use of fossil fuel are becoming serious. To mitigate these issues and reduce our dependence on fossil fuel, alternative energy technologies based on renewable sources need to be developed and adopted, e.g., solar and wind energies. However, solar and wind energies are intermittent; therefore, it is critical for efficient and economical storage of electricity produced by renewable sources to be competitive.1 Rechargeable batteries are one of the most viable options for electrical energy storage (EES). Rechargeable battery systems, such as lead−acid, nickel−cadmium, nickel metal hydride, and lithium ion batteries, have serviced humankind for over a century with their use in a variety of applications, e.g., portable electronic devices and automobiles. As the functionalities of the portable electronics become more sophisticated and the demand for electric vehicles and storage of electricity from renewable sources increases, advanced rechargeable batteries need to be developed. Cost, energy, power, cycle life, safety, and environmental compatibility are some of the most important parameters to be considered.
The success of rechargeable lithium-ion batteries has brought indisputable convenience to human society for the past two decades. However, unlike commercialized intercalation cathodes, high-energy-density sulphur cathodes are still in the stage of research because of the unsatisfactory capacity retention and long-term cyclability. The capacity degradation over extended cycles originates from the soluble polysulphides gradually diffusing out of the cathode region. Here we report an applicable way to recharge lithium-sulphur cells by a simple charge operation control that offers tremendous improvement with various lithium-sulphur battery systems. Adjusting the charging condition leads to long cycle life (over 500 cycles) with excellent capacity retention (>99%) by inhibiting electrochemical reactions along with severe polysulphide dissolution. This charging strategy and understanding of the reactions in different discharge steps will advance progress in the development of lithium-sulphur batteries.
A sandwiched electrode containing pristine Li2S powder in between two layers of binder-free carbon nanotube electrodes is developed. The carbon matrix provides an ion and electron accessible environment, and a space for trapping the active material. Exceptionally high capacities with superior stability and rate capability are obtained.
