Lithium batteries are extremely common in portable electronics. However, over many charge/discharge cycles, lithium metal can form dendrites in these batteries. These structures grow from one electrode and can eventually reach the other electrode and cause a short-circuit, resulting in fires and explosions.

Baohua Li, Tsinghua University, Shenzhen, China, Quan‐Hong Yang, Tsinghua University and Tianjin University, China, and colleagues have developed a gel polymer electrolyte which suppresses dendrite growth. The team used ring-opening polymerization (ROMP) to synthesize a 3D networked copolymer from the diglycidyl ether of bisphenol-A (DEBA), poly(ethylene glycol) diglycidyl ether (PEGDE), and diamino-poly(propylene oxide) (DPPO). DEBA acts as the supporting framework and provides mechanical strength, while PEGDE and DPPO provide fast ion transport.

The resulting gel can be used as an electrolyte for lithium batteries, where it allows the formation of a very homogeneous solid-electrolyte interphase (SEI) layer. This uniform and stable layer, together with the dense structure of the networked gel, prevents the formation of dendrites. Batteries using the synthesized electrolyte show higher cycling stability and improved rate performance compared with cells using conventional liquid electrolytes.

• Dendrite-Free, High-Rate, Long-Life Lithium Metal Batteries with a 3D Cross-Linked Network Polymer Electrolyte,
  Qingwen Lu, Yan-Bing He, Qipeng Yu, Baohua Li, Yusuf Valentino Kaneti, Youwei Yao, Feiyu Kang, Quan-Hong Yang,
  Adv. Mater. 2017.
  DOI: 10.1002/adma.201604460