Hydroxyl compensation effects on the cycle stability of Nickel-Cobalt layered double hydroxides synthesized via solvothermal method

Ni-Co layered double hydroxides (LDHs), as typical battery-type materials with high specific capacity and good rate property, have suffered poor cycle stability. In this work, we develop an in-situ synthesis method, which employs Ni foam as the substrate for crystal growth, simply by compensating a certain amount of hydroxyl in precursors before solvothermal reactions. Results prove that the sample prepared with hydroxyl compensation still exhibits relatively high specific capacity, about 170.6 mAh g^-1 at 10 A g^-1 and good capacity retention, about 63.2% when the current density is increased to 40 A g^-1. Especially, the cycle stability of the electrodes have been improved greatly, with about 99% capacity retention after cycling 3000 times. The improved cycle stability are competitive or superior to those of many other systems with more complicated modifications. Material characterizations indicate that the greatly enhanced cycle stability can be attributed to the strengthened connections between nanosheets and substrates and the inner structure stability of matrix, boned by sufficient hydroxyl.