Spinel LiMn2O4 is considered to be a promising cathode for lithium-ion batteries owing to its low cost, safety, environmental friendliness, high operating voltage and natural abundance of manganese. However, the accelerated dissolution of manganese at elevated temperature results in serious capacity fading, which inhibits its further application in energy storage systems. The dissolution of manganese is mainly caused by the attack of trace acidic species (HF) in liquid electrolyte. Here, we report a facile, universal and effective strategy to suppress the dissolution of manganese at 55 °C by encapsulating LiMn2O4 particles in crumpled Ti3C2Tx nanosheets using an electrostatic self-assembly process. With high electronic conductivity and fast Li+ transport capability, such protective layer reduces direct contact between liquid electrolyte and LiMn2O4 particles, suppressing the dissolution of manganese. The composite exhibits larger discharge specific capacity, enhanced rate and cycling capabilities. The capacity retention ratio can be improved by 18.3% at 55 °C after 200 cycles at 2 C. This study provides a new strategy for suppressing the dissolution of manganese at high temperature and widens the road for the application of 2D MXene in energy storage field. The electrostatic self-assembly strategy we proposed is universal and can be applied in other cathode materials, which can arouse much interest of relevant researchers.