Depends on what operation you seek to improve efficiency for. However, I’ll assume you are referring to full load efficiency.

Some basics:

Reduce the rotor circuit resistance. This will decrease pull out torque, but it will improve running efficiency. In very efficient induction motors, silver is used as the rotor conductor to maximize efficiency. Copper is of course typical. Aluminum is used in cheap induction motors, because it is cheap, and the fabrication method (injecting it while melted) is cheap.

Reduce the air gap. The air gap (between rotor and stator) is necessary for mechanical reasons. However, it compromises the effectiveness of the electric machine. Reducing the air gap will decrease the reluctance, which will decrease the amount to current flowing in the stator necessary to magnetize the rotor. This will of course reduce the I^2R losses and improve efficiency.

Reduce Hysteresis. Use materials with lower hysteresis losses.

Reduce Eddy Currents. Use thinner laminations. This is expensive, but it does reduce losses, particularly in the stator (vs the rotor) where the frequency is much higher.

Improve Permeability. This will decrease reluctance and decrease stray losses (due to more flux staying in the teeth). If you don’t care about cost and really want high efficiency, use high cobalt steel (e.g. HiperCo). This is ~20x more expensive, but it has 50% higher permeability. It is also a manufacturing nightmare, but it does work.

Hiperco and a silver rotor circuit, ought to give you the hand-built Swiss watch of induction motors.

The design of induction motor for Electric Vehicle application is different from that of conventional induction motor, which is used in various drive applications. The performance parameters of an induction motor depend on various design parameters including electrical and mechanical. In this paper study of various parameters such as core axial length, stator inner diameter and rotor outer diameter is done. The effect of these parameters on induction motor characteristics is studied using analytical method. The analysis is done one two different induction motors and their performance is compared.

This link may be useful to your question.

Article Power Factor Correction of 3-Phase Induction Motor Using Swi...

https://www.academia.edu/20101747/Power_Factor_Improvement_for_Three_phase_Induction_motor_using_PSoC_3_Programmable_System_on_Chip_

Ok sir thank you,,,,

My main aim is to get 90% efficiency and ,high torque and high power factor..... for squirrel cage induction motor....

I am using Ansys maxwell Rmxprt software is it sufficient to design?