<p>Nickel-rich cobalt-free cathode materials have received widespread attention due to their advantages of high energy density, low-cost, and environmental friendliness. However, the instability of the structure and surface interface accelerates the capacity degradation of these materials during cycling. Here, we synthesized LiNi_0.9Mn_0.1O₂ (NM91) nickel-rich cobalt-free cathode material by sol–gel method and optimized it by Zr doping to enhance the electrochemical performance. Comprehensive structural characterization confirmed that Zr doping effectively suppressed the volume change and microcrack formation during the H2–H3 phase transition, reduced the side reactions occurring on the surface, and generated a thinner and more stable CEI layer, which effectively prevented the erosion of the electrolyte. As a result, Zr–NM exhibits superior cycling stability and rate performance. Notably, 0.75%Zr–NM shows excellent capacity retention of 92.36% at 1 C and achieves a discharge specific capacity of 138 mAh·g⁻¹ even at a high current density of 10 C.</p>