Graphite (GR) is considered to be the most promising anode material for the commercialization of potassium-ion batteries (PIB) due to its high theoretical specific capacity and low cost. However, GR-based PIB is still not feasible at low temperature (LT) because of the poor kinetics of conventional carbonate electrolytes or the problem of K+ solvent co-embedding based on typical ether electrolytes. 
Here,Wang Hua's team at Beijing University of Aeronautics and AstronauticsThrough electrolyte chemistry, low-temperature potassium storage in GR was successfully realized. 2-methyltetrahydrofuran (MTHF) with ortho-substituents was used as the solvent for the electrolyte. The substitution structure of MTHF weakens the interaction of K+ with solvents. The large steric hindrance caused by the ortho-methyl group further weakens the coordination between K+ and mTHF, thereby improving the kinetics of K+ desolation and preventing the co-embedding of K+- solvent in Gr. Gr||, prepared by matching with the pre-potassiumized 3,4,9,10-perylene-tetracarboxylic acid dianhydride (kPTCDA) cathodeThe KPTCDA full battery can operate in a wide temperature range from -30 to 45 °C and has an energy density of up to 20 Wh kg-197 at -1 °C. 
Figure 1Comparison of the properties and potassium storage properties of gr, hard and soft carbon
In conclusion, this work achieves a low-temperature rechargeable PIB based on the GR anode through electrolyte chemistry. The monodentate ether Mthf of ortho methyl group has a weak K+ solvation effect, which enhances the desolvation ability of K+ and inhibits the co-intercalation of K+ and solvent in GR. In addition, the weakening of the solvation between the solvent and K+ leads to the anion-rich solvation structure of K+, which is conducive to the formation of a Kf-rich SEI layer on the GR and improves the cycling stability of the graphite anode. In addition, k||The GR specific capacity of the GR half-cell at the 0 V cut-off voltage is neglected, which can be attributed to the large resistance of K+ through SEI and the resulting high overpotential of the K metal. The work is based on a 1M KFSi MTHF electrolyte, which enables reversible storage of K+ in the GR anode over a wide temperature range of -30-45°C, while the potassium-ion whole cell achieves an energy density of up to 197Wh kg-1 at -20°C. Therefore, this work has achieved a high-performance GR-based low-temperature rechargeable PIB, and some progress has been made in the commercialization of PIB. 
Figure 2Solvated structure
realizing low-temperature graphite-based rechargeable potassium-ion full battery,angewandte chemie international edition2023 doi: 10.1002/anie.202315624