fig4
![Research on carbon-based and metal-based negative electrode materials via DFT calculation for high potassium storage performance: a review](https://image.oaes.cc/37f9fa8a-26c3-4c29-965c-1a23c647b2d4/em3035.fig.4.jpg)
Figure 4. Theoretical simulations of K atom adsorption and diffusion in different structures. (A) Top view of K+ adsorbed in graphene, along with N, O doping; N doping and O doping structures, and the related adsorption energies. (B) The corresponding side view of the electron density changes of the K atom adsorbed on these structures, and yellow and blue spots represent raised and reduced electron densities, respectively. (C) Top view of the structures with K atom diffusion and associated diffusion energies. The atoms C, N, O, and K are represented by the brown, silver, red, and purple balls, respectively. Copyright 2020, Nano Energy. Theoretical simulations of K adsorption in different structures[11].