Realizing an Energy-Dense Potassium Metal Battery at −40 °C via an Integrated Anode-Free and Dual-Ion Strategy

Potassium (K)-based batteries hold great promise for cryogenic applications owing to the small Stokes radius and weak Lewis acidity of K+. Nevertheless, energy-dense (>200 W h kg–1cathode+anode) K batteries under subzero conditions have seldom been reported. Here, an over 400 W h kg–1cathode+anode K battery is realized at −40 °C via an anode-free and dual-ion strategy, surpassing these state-of-the-art K batteries and even most Li/Na batteries at low temperatures (LTs). By introduction of a strongly associating salt as an additive to this anode-free K battery, an anion-derived solid electrolyte interphase can be established for a highly reversible, zero-excess K plating/stripping behavior on a bare current…

• NN
  National Natural Science Foundation of China

  Awards: 52172178, 52402220, 12374284
• BU
  Beihang University
• BM
  Beijing Municipal Natural Science Foundation

  Award: 2222059
• NP
  National Postdoctoral Program for Innovative Talents

  Award: BX20230452
• NK
  National Key Research and Development Program of China

  Award: 2022YFE0126300
• FR
  Fundamental Research Funds for the Central Universities