Electrocatalytic upgrading of CO to value-added multi-carbon (C2+) compounds is a promising approach to efficient carbon utilization. However, current full-cell systems have low energy conversion effi-ciencies under practical conditions due to the requirement of high cell voltages for an industrially relevant current density. Here, we present a lattice tension strategy to enhance CO chemisorption and carbon-carbon coupling on copper catalysts at high CO cover-ages, which usually cause excessive dipole-dipole repulsion and are detrimental to C-C coupling. A current density of 1.0 A cm -2 with 84% Faradaic efficiency of C2+ compounds is achieved at 2.4 V on a spindle-shaped copper with 4% lattice tension. The C2+ products are formed with nearly 100% selectivity and in a 41% sin-gle-pass yield (on a molar carbon basis). This work demonstrates a great potential of electrocatalytic CO reduction for the practical synthesis of high-value chemicals from CO2 and abundant carbon re-sources.