## 3 Results
### Liquid Structure
#### 3.1.2 Coordination Numbers Distribution  
The simulation enabled deep insight into the numbers of anions in the coordination shell. We determined the number of anions within a spherical shell by collection of every step ions' position and the shell radius was set to the position of the minimum (r\({}_{\rm min}\)) in the PDFs. This constitutes an instantaneous coordination number for that cation.  
Figure 3 shows the coordination numbers distribution around each cation at 1100 K across the concentration. In the ternary melts, there coexisted 3- to 8-fold coordination, with different proportions. The coordination numbers distribution of Li\({}^{+}\) are mainly located in 4 and coexisted with 3-fold and 5-fold coordination. With an increasing LiCl composition, the mainly located 4-fold coordination of Li\({}^{+}\) slightly decreased. Meanwhile, the proportion of 3-fold distribution decreased, and the proportion of 5-fold coordination number increased. For Na-Cl, the coordination numbers, mainly located in 5, coexisted with 4-fold and 6-fold coordination. The 5-fold coordination almost remained constant, with no regard to the composition. However, with an increasing LiCl concentration, the 4-fold coordination largely decreased and 6-fold coordination increased. For K-Cl, the coordination numbers of K\({}^{+}\) were mainly 4, 5, 6, 7, and 8. When x\({}_{\rm LiCl}~{}\leq~{}60\%\), the coordination numbers were mainly located in 6. However, when x\({}_{\rm LiCl}~{}>~{}60\%\), the 6-fold and 7-fold dominated. With an increasing LiCl, the 4-fold and 5-fold coordination of K\({}^{+}\) all decreased, while the higher coordination 7-fold and 8-fold increased.  
The results showed that the proportion of higher coordination numbers for each cation increased as the LiCl molar fraction increased. Combined with our previous study [13; 15], the local structure of Li-Cl in melts is an anomalous, distorted tetrahedron, while Na-Cl and K-Cl are a distorted octahedron. It can be clearly seen that the tendency to form an octahedron became stronger for Na-Cl with an increasing LiCl addition. The anions coordination numbers distribution of K\({}^{+}\) were the most complex. Though sexadentate dominated, the tendency of accommodating more anions for K\({}^{+}\) became stronger. As for Li-Cl, though the portion of 5-fold coordination increased, the tetrahedron structure still dominated. The sharp peak in the PDF indicates a tight coordination of Li-Cl and its height decreases with LiCl addition. It can be found from Table 3 that when the equilibrium distance between the cation and anion gets longer, the coordination numbers of the cation become greater. Combined with PDFs analysis, the LiCl addition increased the mobility of Cl\({}^{+}\), so the tighter coordination structure (the relatively lower coordinated structure) reduced. With the temperature increasing, the coordination became amorphous (the temperature influence on the coordination numbers distribution is provided in Appendix A Figures A5-A7). In Figure 4, there is a snapshot of the A-2 system at 1100 K, and the coordinates around different cations were in a dynamic equilibration.  
Figure 3: The coordination numbers distribution of four compositions at 1100 K for Li-Cl, Na-Cl, K-Cl, respectively.