Magnesium-nitrogen co-doped porous carbon, preparation method and application thereof, and three-electrode battery

The invention belongs to the technical field of electrode materials, and particularly relates to magnesium-nitrogen co-doped porous carbon, a preparation method and application thereof and a three-electrode battery. The preparation method of the magnesium-nitrogen co-doped porous carbon provided by the invention comprises the following steps: carbonizing a natural carbon source to obtain a carbide; mixing the carbide, urea and an activating agent for the first time, and activating to obtain nitrogen-doped porous carbon; mixing the nitrogen-doped porous carbon, a magnesium salt solution and ammonia water for the second time, and carrying out solid-liquid separation to obtain a porous carbon precursor; and calcining the porous carbon precursor to obtain the magnesium and nitrogen co-doped porous carbon. According to the preparation method provided by the invention, a synergistic activation method and calcination are adopted, original natural pore channels of a natural carbon source are reserved to the maximum e