When two is better than four: Batteries based on the reaction of zinc and oxygen have been used for more than a century, but these have been primary (that is, nonrechargeable) cells. These batteries use an alkaline electrolyte and require a four-electron reduction of oxygen to water, which is a slow process. Sun et al. show that with the right choice of nonalkaline electrolyte, the battery can operate using a two-electron zinc-oxygen/zinc peroxide chemistry that is far more reversible. By making the electrolyte hydrophobic, water is excluded from the near surface of the cathode, thus preventing the four-electron reduction. These batteries also show higher energy density and better cycling stability. Science , this issue p. 46

The binder’s influence on the cycling stability of high-energy anodes for lithium-ion batteries is demonstrated. Varying the binder’s nature strongly influences the composite electrode’s performance on deep charging/discharging. If sodium-carboxymethylcellulose is used as binding agent, then a chemical bond between binder and silicon particles can be detected (attenuated total reflection–Fourier transform infrared spectroscopy). Consequently, a reaction mechanism that describes a condensation reaction between the binder and the silicon particles is verbalized. It is shown that, not necessarily the binder’s physical flexibility, but its chemical interaction with the active masses is the major claim leading to long-lasting reversible lithium uptake/release.