Crystal structure refinement, microstructure and ionic conductivity of ATi2(PO4)3 (A=Li, Na, K) solid electrolytes

Decreased Deformation and Heat as well as Improved Interface and Diffusion of Silicon To Enhance Electrochemical Performance and Safety by a Negative Thermal Expansion Material

“…The functional groups and molecular structures of the samples are verified by FT-IR spectroscopy, and the curves are summarized in Figure c. There are two absorption peaks at 3440 and 1630 cm –1 in all curves, corresponding to −OH, mainly due to the presence of moisture in the sample or test environment using the KBr tablet method . There are three peaks at 1233, 1088, and 805 cm –1 in the curve of Si, which correspond to the Si–O–Si. , In the FT-IR curve of LTP, the peak observed at 1036 cm –1 belongs to the PO 4 3– stretching vibration, and the peak at 1237 cm –1 is attributed to the stretch vibration of O–P–O.…”

“…From Figure f, the impedances of both Si and SL3 samples increase greatly after cycling at 60 °C, but the impedances of SL3 are still significantly lower than that of Si. On the other hand, LTP is a fast conductor with a high ionic conductivity of 3.1 × 10 –5 S/cm at 25 °C, and its effects on the diffusion of lithium ions in the Si electrode are discussed by comparing the Li + diffusion coefficient ( D Li + ) which is calculated by the following equations: where R , T , A , n , F , and C represent the gas constant, absolute working temperature, electrode active surface area, number of transferred electrons, Faraday constant, and concentration of Li + ions in Si, respectively. σ in eq is the slope of the curve in Figure h, and the calculated D Li + of Si and SL3 are shown in Figure i.…”

“…From Figure 3f, the impedances of both Si and SL3 samples increase greatly after cycling at 60 °C, but the impedances of SL3 are still significantly lower than that of Si. On the other hand, LTP is a fast conductor with a high ionic conductivity of 3.1 × 10 −5 S/ cm at 25 °C, 36 and its effects on the diffusion of lithium ions in the Si electrode are discussed by comparing the Li + diffusion coefficient (D Li + ) which is calculated by the following equations: 46…”

“…Thus, other low-cost and simply synthesized NTE materials need to be explored to improve the electrochemical performance of battery materials. LTP, a fast ion conductor with a high ionic conductivity of 3.1 × 10 –5 S/cm at 25 °C, is not only an NTE material with a coefficient of thermal expansion of −0.11 × 10 –6 /°C from 25 to 1000 °C, but also easily to be synthesized, green without poisonous elements, and low cost. It is possible to reduce the thermal hazards and stress of batteries through in situ heat absorption and deformation adjustment, avoiding electrode damages like cracking or pulverization of Si particles.…”

“…There are two absorption peaks at 3440 and 1630 cm −1 in all curves, corresponding to −OH, mainly due to the presence of moisture in the sample or test environment using the KBr tablet method. 36 There are three peaks at 1233, 1088, and 805 cm −1 in the curve of Si, which correspond to the Si−O−Si. 35,57 In the FT-IR curve of LTP, the peak observed at 1036 cm −1 belongs to the PO 4 The elemental composition and valence state of SL3 before/ after cycling were analyzed by XPS to analyze the possible enhancement mechanisms, and the results are summarized in Figure 8.…”