Chemically stripping lithium from a vanadium phosphate framework left vacancies for zinc ions, producing a cathode that held 1.51 volts across more than 5,000 cycles with 4.3 per cent volume change.

Zinc-ion batteries are the main contender for the jobs lithium-ion is poorly suited to. They run on water-based electrolytes rather than flammable organic ones, zinc is abundant and cheap, and the chemistry is inherently safer — which makes them attractive for grid storage, where fire risk and material cost matter more than energy per kilogram.

The obstacle is the cathode. A zinc ion carries two charges rather than one, and that doubled charge interacts strongly with the host material it has to move through, which makes zinc ions slow to diffuse and hard on the structures that accommodate them.

A study in Nano Research Energy from Wuhan University takes an indirect route to the problem: build the framework around a different ion, then take that ion out and put zinc in its place.

The research team was led by Dong Zhao of Wuhan University’s Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, with Liangyu Li, Yutong Zhang, Zhongxue Chen, Xiangjun Pu and Limin Zhu of Henan University of Technology.

Two steps

The material is designated ZLVP, with the formula Zn_0.62Li_1.2V₂(PO₄)₃, and the process that makes it has two stages. Lithium ions are chemically extracted from lithium vanadium phosphate, Li₃V₂(PO₄)₃, creating vacant sites; zinc ions are then inserted into those sites.

The reason to do it this way rather than synthesising a zinc compound directly is that the starting material is a known good framework. Lithium vanadium phosphate is a NASICON-type structure — a rigid three-dimensional phosphate lattice with open channels — and it is well characterised as a lithium host because those channels conduct ions well and the framework barely moves as ions come and go.

Pre-zincification keeps the architecture and changes the occupant. The release notes that extracting lithium not only creates vacancies but enlarges the diffusion channels, which is the property a doubly charged ion most needs. Some lithium is left behind, as the formula shows — this is a mixed zinc-lithium phase rather than a complete substitution.

The process also stabilises a mixed-valence state of vanadium, V³⁺/V⁴⁺. Vanadium’s ability to sit at several oxidation states is what lets it accept and release electrons as ions enter and leave, and having both present at the outset means the material starts in a condition it can cycle around rather than having to reach one.

The numbers

Three figures are reported, and they are the three that matter for grid storage.

ZLVP maintained over 5,000 charge-discharge cycles with negligible capacity loss. Operating voltage is 1.51 volts, which the release says is among the highest reported for polyanionic-type zinc-ion battery cathodes. Volume variation during cycling is 4.3 per cent.

The volume figure is the one that explains the cycle life. A cathode swells as ions enter and contracts as they leave, and that repeated mechanical strain is what cracks particles, breaks electrical contact and ends a battery’s life. Materials with low volume change are called zero-strain or near-zero-strain hosts, and they last because nothing is being flexed to failure. At 4.3 per cent, ZLVP is in that category, and 5,000 cycles with negligible loss is what the mechanics would predict.

The voltage matters for a different reason. Zinc-ion cathodes typically operate below 1.5 volts, and since energy is voltage times capacity, a low voltage caps the energy a cell can store however good its capacity is. Pushing the operating voltage up is therefore one of the few ways to make the chemistry competitive rather than merely durable.

“Our material, a chemically pre-zincified compound named ZLVP, survives over 5000 charge-discharge cycles,” Li said, “which is among the highest reported for polyanionic-type zinc-ion battery cathodes.”

What is not reported

The missing number is capacity, and it is the one that would let this be compared with anything.

No specific capacity in milliamp-hours per gram is given, so there is no way to know how much charge the material actually holds — and a cathode with excellent voltage, excellent cycle life and low capacity stores little energy. Polyanionic phosphate frameworks are generally durable and generally lower in capacity than the manganese and vanadium oxides they compete with, which is precisely the trade-off a reader would want quantified here.

Nor is the rate performance reported: how the material behaves when charged or discharged quickly, which for grid storage determines whether it can absorb a solar peak or only trickle.

The cycling conditions are also unstated. Five thousand cycles at a high current rate in a full cell is a very different achievement from 5,000 cycles at a gentle rate in a half cell against a zinc metal counter-electrode, which is how most cathode papers report. And zinc metal anodes have their own well-known failure mode — dendrites that grow through the separator — so a durable cathode is one component of a durable battery rather than the whole of it.

Cost is unaddressed, and the two-step chemical process adds a stage to manufacturing that a directly synthesised material would not need. Vanadium is also considerably more expensive than the manganese used in most commercial zinc-ion work, which bears on the cheapness that is half the argument for the chemistry in the first place.

The paper was published on 22 July 2026. Funding came from the Hubei Provincial Technological Innovation Project, the Key Research and Development Program of Hubei Province and the Fundamental Research Funds for the Central Universities. The release includes no competing-interests statement.

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Notes

1. “Chemical pre-zincification induced Zn0.62Li1.2V2(PO4)3 as high-performance cathode materials for Zn-ion batteries.” Nano Research Energy, 2026. DOI: 10.26599/NRE.2026.9120249.
2. Tsinghua University Press. “Two-step pre-zincification method yields high-performance capabilities in Zn-ion batteries.” EurekAlert!, 10 August 2026. https://www.eurekalert.org/news-releases/1139457.

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