Shorter Electron Paths, Better Batteries CSI’s Blade Cell with Dual-Side Tab Architecture

Large-format lithium-ion blade batteries are a key technology in the push toward higher-capacity, lower-cost energy storage for electric vehicles and grid applications. A new patent from Chinese battery manufacturer CSI Energy Storage addresses one of the central engineering challenges in scaling up these cells: the internal resistance and heat generation caused by long electron travel paths within oversized electrodes.

The Problem

As the capacity of individual lithium-ion cells has grown, manufacturers have turned to large stacked prismatic formats known as blade batteries. These long, flat cells can be packed densely into a battery module without the overhead of individual cell casings, reducing cost and improving volumetric energy density. However, scaling up the physical size of a cell introduces a fundamental electrochemical problem.

In a conventional blade battery, the positive and negative cover plates are located at opposite ends of the cell along its length. During charging and discharging, electrons must travel the full length of the cell between these terminals. In a long blade cell – some designs extend to over one metre in length – this creates a significant internal resistance due to the sheer distance travelled. The resulting polarisation causes uneven charge distribution, reduces cycle life, increases heat generation, and limits the power available at low temperatures or under high-load conditions.

The existing approach of positioning tabs at a single edge of each electrode plate exacerbates this problem, because current collection becomes uneven across the plate surface, concentrating current density near the tab and reducing the effective utilisation of the active material.

What This Invention Does

The blade battery described in this patent rearranges the tab geometry of both positive and negative plates so that current is collected from two adjacent edges rather than one. Each positive plate carries a first tab along one edge and a second tab along an adjacent edge. Similarly, each negative plate carries a third tab along one edge and a fourth tab at an adjacent edge.

The positive cover plate wraps around two adjacent edges of the battery and connects to both the first and second tabs, forming a continuous L-shaped positive electrode collection path. The negative cover plate does the same for the third and fourth tabs. By distributing current collection around two sides of each plate rather than one, the maximum distance any electron must travel within the cell is significantly reduced – cutting internal resistance and the associated heat generation and polarisation effects.

Each tab is configured as a full tab that extends continuously along the entire corresponding edge of the plate, maximising the contact area between the electrode material and the current collector. The tabs are bent relative to the plate surface and welded to the cover plates, using an aluminium conductive sheet for the positive side and a copper conductive sheet for the negative side.

Key Features

Two-adjacent-edge tab configuration. Both positive and negative electrode plates carry tabs at two adjacent (perpendicular) edges rather than a single edge, distributing current collection around two sides of the cell and reducing internal resistance in large-format cells.

L-shaped cover plates. The positive and negative cover plates each span two adjacent edges of the blade battery, matching the two-edge tab geometry and forming complete L-shaped current collection paths.

Full tab design. Each tab extends continuously along the full length of its corresponding plate edge, maximising contact area and ensuring uniform current distribution across the plate surface.

Bent tabs with conductive sheets. Tabs are bent at right angles relative to the plate surface and connected via welded conductive sheets – aluminium for positive, copper for negative – to the respective end plates.

Encapsulation housing. An outer housing encloses the stacked positive and negative plates with open end faces at the blade battery ends, exposing the positive and negative end plates while protecting the electrode stack.

Specified dimensional ratios. The design is optimised for blade cells with lengths from 500 mm to 1,350 mm, thickness from 25 mm to 40 mm, and width from 200 mm to 319 mm, with defined length-to-thickness, length-to-width, and width-to-thickness ratios to maintain the performance benefits.

Who Is Behind It?

The application is filed jointly by CSI Energy Storage Co., Ltd. and its manufacturing affiliate CSI Energy Storage Technology (Dafeng) Co., Ltd., both based in China. The named inventors are Wang Chunlei, Qian Jianfeng, Dong Zhu, Zhang Hailin, and Gao Lijun. The Australian application claims priority from Chinese patent application CN 202411223558.6, filed 3 September 2024. Australian patent attorneys Minter Ellison in Sydney are managing the application.

Why It Matters

Internal resistance is one of the most consequential parameters in large-format lithium-ion cells. Lower internal resistance directly translates to higher round-trip efficiency, lower heat generation, better performance at low temperatures, and improved cycle life – all factors that matter enormously in electric vehicle drivetrains and grid-scale energy storage systems. The two-adjacent-edge tab architecture described in this patent is a structural solution to a problem that cannot be solved through chemistry alone as blade cells grow longer.

The trend toward larger individual cells is driven by cost economics: fewer cells mean fewer welds, fewer quality control points, and less packaging material per unit of energy stored. As manufacturers push cell lengths beyond one metre, the current collection geometry becomes increasingly critical. A full-tab L-shaped collection design that reduces the effective electron path by addressing both the length and width dimensions of the cell could enable the next scale-up step in blade battery manufacturing while keeping internal resistance within acceptable bounds.

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AU 2025308129 was published in the Australian Official Journal of Patents on 19 March 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.

Related Concepts

Internal resistance in large-format lithium-ion cells is a function of both material properties and geometry. As blade batteries extend beyond one metre in length, the current collection geometry becomes the limiting factor – electrons travelling the full cell length generate resistive losses that reduce efficiency and increase heat.

The two-adjacent-edge tab design described in this patent directly reduces the maximum electron path length by collecting current from two sides of each plate, analogous to the way energy density improvements in cell-to-pack designs require rethinking internal architecture rather than just chemistry. This structural approach complements ongoing advances in electrode materials and electrolytes.