Using electrical vehicles instead of traditional ones is very important for reducing fossil oil consumption and carbon emissions. Spinel LiNi0.5Mn1.5O4 is considered as a promising cathode material for advanced lithium ion batteries owing to its high power density. Nevertheless, it suffers badly from the interfacial reactions with the electrolyte at high operation potential, which degrades its electrochemical performance. The strategy of the present study is to prevent direct contact between LiNi0.5Mn1.5O4 and the electrolyte by using a surface coating in order to reduce solid electrolyte interfacial reactions and consequently enhance its cycling performance. The experimental results indicated that as-prepared LiNi0.5Mn1.5O4 sintered at 900 °C possessed the highest initial specific capacity of 132.4 mA h·g−1 at 0.2 C rate, with 81.0% initial capacity retention after 50 cycles. Coating AlF3 on the particle surfaces of LiNi0.5Mn1.5O4 using a modified solid-state method can improve its electrochemical properties by enhancing its initial specific capacity from 104.6 to 109.1 mA h·g−1 and increasing its capacity retention from 80.6 to 92.1% at the 10 C rate after 100 cycles.