# A multisite super-crosslinked sulfur-heterocyclic polymer cathode for high-voltage and low-temperature aluminum–organic batteries

## TL;DR

This paper introduces a new polymer cathode for aluminum batteries that improves voltage and durability at low temperatures.

## Contribution

A novel sulfur-heterocyclic polymer cathode with high voltage and low-temperature stability is developed for aluminum–organic batteries.

## Key findings

- The cathode achieves an average operating voltage of 1.7 V, a significant improvement over existing AOBs.
- The cathode enables a high energy density of 255 Wh kg−1, surpassing conventional graphite cathodes.
- The battery retains nearly 100% capacity after 12,000 cycles at −20°C due to structural stability.

## Abstract

Simultaneously attaining high energy density and long cycling life remains a critical challenge for aluminum–organic batteries (AOBs) due to low operating voltage, limited active sites and unstable coordination structure of organic cathodes. Herein, we design a multisite super-crosslinked sulfur-heterocyclic polymer cathode. The electronegative sulfur heterocycles can significantly weaken the electron-donating effect, promoting the operating voltage to 2.0 V (average ∼1.7 V), which is a breakthrough for AOBs (<1.5 V for almost all AOBs). Tailoring the linking patterns of polymers to increase active sites can maximize redox activity to 12-electron-transfer, contributing to a high capacity of 150 mAh g−1. The designed organic cathode achieves 255 Wh kg−1 energy density, breaking the upper limit of conventional graphite cathodes (∼200 Wh kg−1). Notably, the weak coordination interaction between C‒S+‒C radicals and AlCl4− carriers ensures structural stability, enabling the battery’s excellent low-temperature durability, with almost 100% capacity retention after 12 000 cycles at −20°C.

This work designs a multisite, super-crosslinked sulfur-heterocyclic polymer cathode with weak electron-donating effect and multi-electron transfer capability, thus achieving high operating voltage and superior low-temperature durability in aluminum–organic batteries.