Integrated AlGaAs/GaAs betavoltaic arrays with low self-discharge LiCoO2 batteries for efficient β-energy conversion and storage

Nuclear batteries are emerging power devices that convert radioactive decay energy into electricity. In this study, we developed a six-layer AlGaAs/GaAs heterostructure betavoltaic cell array by serially connecting six monocells on a single printed circuit board substrate, and a low-self-discharge Li-ion battery was integrated into the nuclear energy conversion and storage system. Through dual strategies of electrode modification and electrolyte optimization, we constructed an efficient hybrid energy conversion and storage system. To address self-discharge under microcurrent charging, two approaches were implemented: (1) constructing graphene-based conductive networks within LiCoO2 cathodes to reduce interfacial impedance via face-contact mechanisms, suppress Co3+ dissolution, and accelerate Li+ diffusion; (2) incorporating fumaronitrile additive into the electrolyte to preferentially form stable cathode electrolyte interphase films, thereby inhibiting electrolyte decomposition and metal-ion catalyzed side reactions. These strategies suppressed self-discharge via physical/chemical pathways.