The effect of the interlayer anions on the electrochemical performance of layered double hydroxide electrode materials

Both high energy density and high power density are vitally required for new applications such as electric vehicles. Here we present a comparison of two well-crystallised layered double hydroxides, [Ni₄Al(OH)₁₀]OH and [Ni₄Al(OH)₁₀]NO₃, which shows that the former can maintain a better discharge capacity, 294-299 mAh g⁻¹, than the latter, 233-287 mAh g⁻¹ at a current density of 2000 mA g⁻¹ within about 300 cycles, although both electrodes deliver a similar capacity of 326 mAh g⁻¹ at 200 mA g⁻¹ initially. It is believed that both the more watery interlayer space in [Ni₄Al(OH)₁₀]OH than in [Ni₄Al(OH)₁₀]NO₃ and the morphologic changes induced by anion exchange of NO₃⁻ by OH⁻ during electrochemical cycles play key roles in their behaviour.