Spinel LiNi_0.5−xMn_1.5+xO₄ (LNMO) has attracted intensive interest for lithium-ion battery due to its high voltage and high energy density. However, severe capacity fade attributed to unstable surface structure has hampered its commercialization. Oxygen vacancies (OVs) tend to occur in the surface of the material and lead to surface structure reconstruction, which deteriorates the battery performance during electrochemical cycling. Here, we utilize high-temperature-shock (HTS) method to synthesize LNMO materials with fewer surface OVs. Rapid calcination drives lower surface OVs concentration, reducing the content of Mn³⁺ and surface reconstruction layers, which is beneficial to obtain a stable crystal structure. The LNMO material synthesized by HTS method delivers an initial capacity of 127 mAh·g⁻¹ at 0.1 C and capacity retention of 81.6% after 300 cycles at 1 C, and exhibits excellent performance at low temperature.