The CR2025 type full cell was assembled with LiFePO
4 as the cathode material and lithium metal foil as the negative electrode. The constant current charging and discharging of full cells was measured at 60 ℃ in the voltage range of 2.5–4.2 V.
Fig. 5a shows the cycling performance of Li|PEO/LiTFSI|LiFePO
4 and Li|PEO/LiTFSI/0.2LiCUST-701|LiFePO
4 cells at 0.2 C. The Li|PEO/LiTFSI|LiFePO
4 cell had fast capacity decay and low coulomb efficiency. The first discharge capacity after activation was 116 mAh/g and after 100 cycles the capacity was 52 mAh/g, which was only 44.8% of the initial capacity. In contrast, the Li|PEO/LiTFSI/0.2LiCUST-701|LiFePO
4 cell exhibited a gentle discharge curve with a capacity of 148 mAh/g at the first discharge and 134 mAh/g (a 90.5% capacity retention) after 100 cycles. Meanwhile, the coulomb efficiency rate was almost close to 100%. Comparing the multiplicity performance of the two cells (
Fig. 5b), the capacities of Li|PEO/LiTFSI|LiFePO
4 cell at 0.1, 0.2, 0.5, 1 and 2 C current rates were 131, 115, 100, 73 and 41 mAh/g, respectively. Li|PEO/LiTFSI/0.2LiCUST-701|LiFePO
4 cell exhibited higher capacity with capacities of 150, 144, 131, 117, and 98 mAh/g at different current rates of 0.1, 0.2, 0.5, 1, and 2 C, respectively. And Li|PEO/LiTFSI/0.2LiCUST-701|LiFePO
4 had excellent capacity recovery from 98 mAh/g to 145 mAh/g with the current density changing from 2 C to 0.1 C, which essentially matched with its initial capacity. Then, the cycling capability of the Li|PEO/LiTFSI/0.2LiCUST-701|LiFePO
4 cell with high current density has been investigated, which showed a first discharge capacity of 124 mAh/g at 2 C and a stable discharge capacity of 103 mAh/g (an 83% capacity retention) after 270 charge/discharge cycles (
Fig. 5c). Meanwhile, the coulomb efficiency was close to 100%. The addition of LiCUST-701 could effectively inhibit the growth of lithium dendrites and improve the cycling stability of solid-state batteries.