▎ 摘　　要

NOVELTY - A composite negative electrode material comprises a polycarboxylate potassium salt dispersed on a surface of a graphite material comprising 50 mg/L graphite. The side length of a nanosheet of the polycarboxylate potassium salt is 1-5 microns. USE - Composite negative electrode material used for producing potassium-ion battery, lithium-ion battery, sodium-ion battery, and calcium-ion battery (all claimed) used in electric vehicle. ADVANTAGE - The negative electrode material has high potassium storage theoretical capacity, and improved stability, charging and discharging process can effectively relieve the volume expansion problem of organic salt, so as to improve the stability of the electrode, multiplying power performance and coulomb efficiency. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: preparation of the composite negative electrode material; a potassium-ion battery; and preparation of the potassium-ion battery.