Fast and reversible thermoresponsive polymer switching materials for safer batteries


Safety issues have been a long-standing obstacle impeding large-scale adoption of next-generation high-energy-density batteries. Materials solutions to battery safety management are limited by slow response and small operating voltage windows. Here we report a fast and reversible thermoresponsive polymer switching material that can be incorporated inside batteries to prevent thermal runaway. This material consists of electrochemically stable graphene-coated spiky nickel nanoparticles mixed in a polymer matrix with a high thermal expansion coefficient. The as-fabricated polymer composite films show high electrical conductivity of up to 50 S cm−1 at room temperature. Importantly, the conductivity decreases within one second by seven to eight orders of magnitude on reaching the transition temperature and spontaneously recovers at room temperature. Batteries with this self-regulating material built in the electrode can rapidly shut down under abnormal conditions such as overheating and shorting, and are able to resume their normal function without performance compromise or detrimental thermal runaway. Our approach offers 103–104 times higher sensitivity to temperature changes than previous switching devices.

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Figure 1: Schematic illustration of safe battery design.
Figure 2: Structure and composition of graphene-coated nano-spiky Ni and as-fabricated TRPS material.
Figure 3: Physical properties of TRPS film.
Figure 4: Battery performance.
Figure 5: COMSOL simulation of battery behaviour after nail shorting.


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This work was partially supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC02-76-SF00515 and by the Precourt Institute for Energy at Stanford University. We thank K. Yan for discussions and J. Tok for proof reading of the manuscript.

Author information




Z.B., Y.C. and Z.C. conceived and designed the experiment. Z.C. carried out materials fabrication, characterization and testing. P.-C.H. conducted COMSOL simulations. J.L. performed DSC measurements. Y.L. conducted the graphene coating for nano-spiky nickel particles. J.W.F.T. and N.L. did the XPS and Raman characterization, respectively. C.W., S.C.A. and J.L. provided constructive advice for the experiment and figure preparation. Z.C. wrote the first draft. Z.B. and Y.C. revised the manuscript. All authors made comments on the paper.

Corresponding authors

Correspondence to Yi Cui or Zhenan Bao.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Figures 1–16, Supplementary Table 1 and Supplementary References. (PDF 1548 kb)

Supplementary Video 1

Demonstration of the fast thermal switching behavior of TRPS devices made by PE/GrNi. (MOV 7458 kb)

Supplementary Video 2

Demonstration of slicing properties of TRPS film. (MOV 25386 kb)

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Chen, Z., Hsu, P., Lopez, J. et al. Fast and reversible thermoresponsive polymer switching materials for safer batteries. Nat Energy 1, 15009 (2016).

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