This is according to CHATGPT so in terms of density you are probably correct though in terms of reliability speed of recharging there probably are improvements

This is according to CHATGPT so in terms of density you are probably correct though in terms of reliability speed of recharging there probably are improvements iPhone 5: Dimensions: 51 x 39 x 3.6 mm (2.01 x 1.54 x 0.14 in) Capacity: 1440 mAh Voltage: 3.8 V iPhone 5s: Dimensions: 51 x 39 x 3.8 mm (2.01 x 1.54 x 0.15 in) Capacity: 1560 mAh Voltage: 3.8 V iPhone SE (1st generation): Dimensions: 51 x 39 x 3.95 mm (2.01 x 1.54 x 0.16 in) Capacity: 1624 mAh Voltage: 3.82 V iPhone 6: Dimensions: 66.4 x 51.8 x 3.8 mm (2.61 x 2.04 x 0.15 in) Capacity: 1810 mAh Voltage: 3.82 V iPhone 6s: Dimensions: 65.6 x 51.7 x 3.8 mm (2.58 x 2.04 x 0.15 in) Capacity: 1715 mAh Voltage: 3.82 V iPhone 7: Dimensions: 73.1 x 32.4 x 5.2 mm (2.88 x 1.28 x 0.20 in) Capacity: 1960 mAh Voltage: 3.8 V iPhone 8: Dimensions: 74.5 x 26.6 x 6.9 mm (2.94 x 1.05 x 0.27 in) Capacity: 1821 mAh Voltage: 3.82 V iPhone SE (2nd generation): Dimensions: 67.3 x 40.9 x 3.73 mm (2.65 x 1.61 x 0.15 in) Capacity: 1821 mAh Voltage: 3.82 V iPhone X: Dimensions: 88.9 x 32.5 x 3.25 mm (3.5 x 1.28 x 0.13 in) Capacity: 2716 mAh Voltage: 3.81 V iPhone XS: Dimensions: 87.16 x 32.61 x 2.96 mm (3.43 x 1.28 x 0.12 in) Capacity: 2658 mAh Voltage: 3.81 V iPhone XR: Dimensions: 76.0 x 30.8 x 3.25 mm (2.99 x 1.21 x 0.13 in) Capacity: 2942 mAh Voltage: 3.81 V iPhone 11: Dimensions: 90.0 x 31.9 x 3.25 mm (3.54 x 1.26 x 0.13 in) Capacity: 3110 mAh Voltage: 3.83 V iPhone 12: Dimensions: 81.5 x 32.4 x 4.1 mm (3.21 x 1.28 x 0.16 in) Capacity: 2815 mAh Voltage: 3.83 V iPhone 13: Dimensions: 84.5 x 30.9 x 5.7 mm (3.33 x 1.22 x 0.22 in) Capacity: 3095 mAh Voltage: 3.83 V